Radon in Water, Air, and Soil
- Details
- Written by Mr. Brian Oram, PG
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Radon causes an estimated 14,000 lung cancer deaths each year. It is the earth's only naturally produced radioactive gas and comes from the breakdown of uranium in soil, rock, and water. You cannot see or smell radon, but it can become a health hazard when it accumulates indoors. It can enter your home through cracks and openings in the foundation floor and walls. When radon decays and is inhaled into the lungs, it releases energy that can damage the DNA in sensitive lung tissue and cause cancer.
Radon is a gas produced by the radioactive decay of the element radium. Radioactive decay is a natural, spontaneous process in which an atom of one element decays or breaks down to form another element by losing atomic particles (protons, neutrons, or electrons). When solid radium decays to form radon gas, it loses two protons and two neutrons. These two protons and two neutrons are called an alpha particle, which is a type of radiation. The elements that produce radiation are called radioactive. Radon itself is radioactive because it also decays, losing an alpha particle and forming the element polonium.
Elements that are naturally radioactive include uranium, thorium, carbon, and potassium, as well as radon and radium. Uranium is the first element in a long series of decay that produces radium and radon. Uranium is referred to as the parent element, and radium and radon are called daughters. Radium and radon also form daughter elements as they decay.
The decay of each radioactive element occurs at a very specific rate. How fast an element decays is measured in terms of the element "half-life", or the amount of time for one half of a given amount of the element to decay. Uranium has a half-life of 4.4 billion years, so a 4.4-billion-year-old rock has only half of the uranium with which it started. The half-life of radon is only 3.8 days. If a jar was filled with radon, in 3.8 days only half of the radon would be left. But the newly made daughter products of radon would also be in the jar, including polonium, bismuth, and lead . Polunium is also radioactive - it is this element, which is produced by radon in the air and in people's lungs, that can hurt lung tissue and cause lung cancer.
Radioactivity is commonly measured in picocuries (pCi). This unit of measure is named for the French physicist Marie Curie, who was a pioneer in the research on radioactive elements and their decay. One pCi is equal to the decay of about two radioactive atoms per minute.
Radon is measured in picocuries per liter and written as (pCi/L). One picocurie is one-trillionth of 37 billion disintegrations per second. One curie, named for Marie Curie, the discoverer of metallic radium, is the amount of radiation given off by one gram of radium.
Radon decay products (RDPs) such as polonium(218), lead(214), bismuth(214), and polonium(214), lead(210), bismuth(210), polonium(210) are measured in working levels (WL). A working level is the amount of RDP which normally results when the decay products are in equilibrium (maximum concentration) with 100 picocuries of radon in the air.
RDPs are difficult to measure in a house though, because among other problems, RDPs have a static charge and tend to plate out (stick) to walls, furniture, clothing, dust, smoke, and other objects and substances.
One of the problems with understanding the amount of risk due to a specific radon level measurement is that the risk statistics are based on an average lifetime (70 years) spent in an exposed area, even though the average American moves every 7 years, and is thus exposed to many different radon levels.
The American Society of Heating, Refrigeration, and Air Conditioning Engineers has set the lowest level, which suggests a radon action level of 2 picocuries per liter or less for commercial buildings and residences. The EPA has adopted a 4 picocuries per liter of air action level. The U.S. Mine Safety and Health Administration, on the other hand, suggests an action level of 16 picocuries per liter (while miners are in underground mines).
Because the level of radioactivity is directly related to the number and type of radioactive atoms present, radon and all other radioactive atoms are measured in picocuries. For instance, a house having 4 picocuries of radon per liter of air (4 pCi/L) has about 8 or 9 atoms of radon decaying every minute in every liter of air inside the house. A 1,000-square-foot house with 4 pCi/L of radon has nearly 2 million radon atoms decaying in it every minute.
Radon levels in outdoor air, indoor air, soil air, and ground water can be very different. Outdoor air ranges from less than 0.1 pCi/L to about 30 pCi/L, but it probably averages about 0.2 pCi/L. Radon in indoor air ranges from less that 1 pCi/l to about 3,000 pCi/L, but it probably averages between 1 and 2 pCi/L. Radon in soil air (the air that occupies the pores in soil) ranges from 20 or 30 pCi/L to more than 100,000 pCi/L; most soils in the United States contain between 200 and 2,000 pCi of radon per liter of soil air. The amount of radon dissolved in ground water ranges from about 100 to nearly 3 million pCi/L.
Why do radon levels vary so much between indoor air, outdoor air, soil air, and ground water? Why do some houses have high levels of indoor radon while nearby houses do not? The reasons lie primarily in the geology of radon - the factors that govern the occurrence of uranium, the formation of radon, and the movement of radon, soil gas, and ground water.
Radon is a naturally-occurring radioactive gas that may cause cancer, and may be found in drinking water and indoor air. Some people who are exposed to radon in drinking water may have increased risk of getting cancer over the course of their lifetime, especially lung cancer. Radon in soil under homes is the biggest source of radon in indoor air, and presents a greater risk of lung cancer than radon in drinking water. The map shown above represents the potential for a radon problem based on geologic boundaries, so that rock and soil units with similar radon generation and transport characteristics.
Radon will dissolve into groundwater and can be transported some way from the source. When the water is exposed to air the radon is released. If a well or bore hole is supplied from such water, the use in an enclosure such as a dwelling or greenhouse will release radon into that environment. Showers and sprays are a prime release method and the greater the water usage, the greater the potential radon problem.
The United States Environmental Protection Agency is reportedly prepared to set an maximum contaminant Level of 300 to 4,000 pico curies per liter for radon in drinking water. At high levels (i.e. among mine workers) radon is a known human carcinogen. There is, however, epidemiological evidence that low levels present no increase cancer risk (Journal of the National Cancer Institute, Dec. 1994). Additional research is needed before the true level of risk associated with low level radon is known.
| RADON RISK IF YOU SMOKE | |||
|---|---|---|---|
| Radon Level | If 1,000 people who smoked were exposed to this level over a lifetime... | The risk of cancer from radon exposure compares to... | WHAT TO DO: Stop smoking and... |
| 20 pCi/L | About 135 people could get lung cancer | 100 times the risk of drowning | Fix your home |
| 10 pCi/L | About 71 people could get lung cancer | 100 times the risk of dying in a home fire | Fix your home |
| 8 pCi/L | About 57 people could get lung cancer | Fix your home | |
| 4 pCi/L | About 29 people could get lung cancer | 100 times the risk of dying in an airplane crash | Fix your home |
| 2 pCi/L | About 15 people could get lung cancer | 2 times the risk of dying in a car crash | Consider fixing between 2 and 4 pCi/L |
| 1.3 pCi/L | About 9 people could get lung cancer | (Average indoor radon level) | (Reducing radon evels below 2 pCi/L is difficult.) |
| 0.4 pCi/L | About 3 people could get lung cancer | (Average outdoor radon level) | |
| Note: If you are a former smoker, your risk may be lower. | |||
| RADON RISK IF YOU HAVE NEVER SMOKED | |||
|---|---|---|---|
| Radon Level | If 1,000 people who never smoked were exposed to this level over a lifetime... | The risk of cancer from radon exposure compares to... | WHAT TO DO: |
| 20 pCi/L | About 8 people could get lung cancer | The risk of being killed in a violent crime | Fix your home |
| 10 pCi/L | About 4 people could get lung cancer | Fix your home | |
| 8 pCi/L | About 3 people could get lung cancer | 10 times the risk of dying in an airplane crash | Fix your home |
| 4 pCi/L | About 2 people could get lung cancer | The risk of drowning | Fix your home |
| 2 pCi/L | About 1 person could get lung cancer | The risk of dying in a home fire | Consider fixing between 2 and 4 pCi/L |
| 1.3 pCi/L | Less than 1 person could get lung cancer | (Average indoor radon level) | (Reducing radon levels below 2 pCi/L is difficult.) |
| 0.4 pCi/L | Less than 1 person could get lung cancer | (Average outdoor radon level) | |
| Note: If you are a former smoker, your risk may be higher. | |||
It's never too late to reduce your risk of lung cancer. Don't wait to test and fix a radon problem. If you are a smoker, stop smoking.
Radon Water Treatment - aeration (90+% reduction), carbon block filtration (85+% reduction)
Option 4: Radiological Testing (Laboratory Testing)
The Standard Radiological water testing package includes Uranium, Gross Alpha & Beta and Radon in Water.
Deluxe Radiological water testing package includes Uranium, Gross Alpha & Beta, Radon and Radium 226 & 228.
Radon Testing - Air Monitoring (Do It Yourself)
Radon Gas Test Kit AccuStar Charcoal Short Term 48-96 Hour Test
Accustar Labs Long-Term Alpha Track Radon Test Kit
Corentium Home Radon Detector by Airthings 223 Portable,Lightweight, Easy-to-Use, (3) AAA Battery Operated, USA Version, pCi/L
RadonSeal® Plus Deep-Penetrating Concrete Sealer (5-gal)Basement Waterproofing & Radon Mitigation In One! | Seals Concrete Permanently Against Basement Moisture
Radon Testing - Water Monitoring (Do It Yourself)
Accustar WTR 100 Radon in Water Test Kit / For Home's With Private Well Water
Looking for a Certified Radon Sampling,Testing, or Mitigation Professional
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New Online Training Courses for Professional - http://online-training-courses.info/
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Radon Training Courses (New Homes)
Proposed EPA Rule
Setting Radon in Water Limits
EPA Radon Maps for Each State
The Geology of Radon
Radon Control Building Standards for New Homes
Radon in Groundwater of Lower Susquehanna River and Potomac River
Radon Levels in PA by Zip Code
Radiological Contaminants Uranium Radon Radium Alpha Beta Drinking Water
- Details
- Written by Mr. Brian Oram, PG
Drinking Water Testing
Water Check with Metals Pesticides and Uranium
Radon Alpha Beta Radium
| CHEMICAL | USEPA MCL | USEPA MCLG | SOURCES, DESCRIPTIONS | HEALTH EFFECTS | RECOMMENDATIONS FOR TREATMENT |
|---|---|---|---|---|---|
| Beta/photon emitters (I) and (P) | 4millirems/year | Zero | Natural and man-made deposits | Health Effects: Cancer group A | Coagulation and Filtration, Ion Exchange, Reverse Osmosis |
| Alpha (gross) | 15 Picocuries/l | Zero | Natural deposits | Cancer group A | Coagulation and Filtration, Reverse Osmosis |
| Radium 226, and 228 (combined) | 5 Picocuries/l | Zero | Natural deposits | Cancer group A (226-Head Carcinomas, 228-Bone Cancer) | Lime Softening, Ion Exchange, Reverse Osmosis |
| Radon | 400 to 3,000 pCi/l (Proposed) |
Zero | Natural deposits | Cancer group A. Effect of low levels of radon and of consumed (versus inhaled) radon is in dispute. High levels shown to cause lung cancer when inhaled. | Aeration |
| Uranium | 0.02 mg/l (Proposed) | Zero | Natural deposits | Cancer group A, also kidney effects. Accumulates in bones. | Coagulation and Filtration, Lime Softening, Anion Exchange |
Option 4: Radiological Testing (Laboratory Testing)
The Standard Radiological water testing package includes Uranium, Gross Alpha & Beta and Radon in Water.
Deluxe Radiological water testing package includes Uranium, Gross Alpha & Beta, Radon and Radium 226 & 228.
Radon Testing - Air Monitoring (Do It Yourself)
Radon Gas Test Kit AccuStar Charcoal Short Term 48-96 Hour Test
Accustar Labs Long-Term Alpha Track Radon Test Kit
Corentium Home Radon Detector by Airthings 223 Portable,Lightweight, Easy-to-Use,
(3) AAA Battery Operated, USA Version, pCi/L
RadonSeal® Plus Deep-Penetrating Concrete Sealer (5-gal) Basement Waterproofing & Radon Mitigation In One!
Seals Concrete Permanently Against Basement Moisture
Radon Testing - Water Monitoring (Do It Yourself)
Accustar WTR 100 Radon in Water Test Kit / For Home's With Private Well Water
Looking for a Certified Radon Sampling,Testing, or Mitigation Professional
Online Training Courses
New Online Training Courses for Professional - http://online-training-courses.info/
LEED- AP / Green Associate Training/ Professional Development Hours Courses
Radon Training Courses (New Homes)
Proposed EPA Rule
Setting Radon in Water Limits
EPA Radon Maps for Each State
The Geology of Radon
Radon Control Building Standards for New Homes
Radon in Groundwater of Lower Susquehanna River and Potomac River
Radon Levels in PA by Zip Code
Sulfur Gas, Hydrogen Sulfide, Rotten Egg Odors - Clean Drinking Water Systems
- Details
- Written by Mr. Brian Oram, PG
Pipe Corrosion, Mineral Scale, Microbiological Regrowth, and Taste and Odor Problems
Shock Well and System Disinfection - Short Term and Potential Long-Term Solution
Two forms of sulfur are commonly found in drinking water supplies: sulfate and hydrogen sulfide. Both forms are nuisances that usually do not pose a health risk at the concentrations found in domestic water supplies.
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Sources of Sulfate and Hydrogen Sulfide in Drinking Water
Sulfates and Hydrogen Sulfide
Sulfates are a combination of sulfur and oxygen and are a part of naturally occurring minerals in some soil and rock formations that contain groundwater. The mineral dissolves over time and is released into groundwater. In addition, this problem may be related to a community hazard, such as a: landfill, leaky fuel tank, pipeline, old septic system, chemical lab, and many other community hazards. It may be wise to run a Community Hazard Report and Identify the Historic / Active Hazards within Your Neighborhood.
Sulfur-reducing bacteria, which use sulfur as an energy source, are the primary producers of large quantities of hydrogen sulfide. These bacteria chemically change natural sulfates in water to hydrogen sulfide. Sulfur-reducing bacteria live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners and water heaters. These bacteria usually flourish on the hot water side of a water distribution system.
Hydrogen sulfide gas also occurs naturally in some groundwater. It is formed from decomposing underground deposits of organic matter such as decaying plant material. It is found in deep or shallow wells and also can enter surface water through springs, although it quickly escapes to the atmosphere. Hydrogen sulfide often is present in wells drilled in shale or sandstone, or near coal or peat deposits or oil fields.
Occasionally, an electric water heater is a source of hydrogen sulfide odor. The magnesium corrosion control rod present in many water heaters can chemically reduce naturally occurring sulfates to hydrogen sulfide.
Indications of Sulfate and Hydrogen Sulfide
Sulfate
Sulfate minerals can cause scale to build up in water pipes similar to other minerals and may be associated with a bitter taste in water that can have a laxative effect on humans and young livestock. Elevated sulfate levels in combination with chlorine bleach can make cleaning clothes difficult. Sulfur-oxidizing bacteria produce effects similar to those of iron bacteria. They convert sulfide into sulfate, producing a dark slime that can clog plumbing and/or stain clothing. Blackening of water or dark slime coating the inside of toilet tanks may indicate a sulfur-oxidizing bacteria problem. Sulfur-oxidizing bacteria are less common than sulfur-reducing bacteria. The well may have a biofouling problem and a corrosion related problem.
Hydrogen Sulfide
Hydrogen sulfide gas produces an offensive "rotten egg" or "sulfur water" odor and taste in the water. In some cases, the odor may be noticeable only when the water is initially turned on or when hot water is run. Heat forces the gas into the air which may cause the odor to be especially offensive in a shower. Occasionally, a hot water heater is a source of hydrogen sulfide odor. The magnesium corrosion control rod present in many hot water heaters can chemically reduce naturally occurring sulfates to hydrogen sulfide.
A nuisance associated with hydrogen sulfide includes its corrosiveness to metals such as iron, steel, copper and brass. It can tarnish silverware and discolor copper and brass utensils. Hydrogen sulfide also can cause yellow or black stains on kitchen and bathroom fixtures. Coffee, tea and other beverages made with water containing hydrogen sulfide may be discolored and the appearance and taste of cooked foods can be affected.
High concentrations of dissolved hydrogen sulfide also can foul the resin bed of an ion exchange water softener. When a hydrogen sulfide odor occurs in treated water (softened or filtered) and no hydrogen sulfide is detected in the non-treated water, it usually indicates the presence of some form of sulfate-reducing bacteria in the system. Water softeners provide a convenient environment for these bacteria to grow. A "salt-loving" bacteria, that uses sulfates as an energy source, may produce a black slime inside water softeners.
Potential Health Effects
Sulfate
Sulfate may have a laxative effect that can lead to dehydration and is of special concern for infants. With time, people and young livestock will become acclimated to the sulfate and the symptoms disappear. Sulfur-oxidizing bacteria pose no known human health risk. The maximum contaminate level is 250 mg/L.
Hydrogen Sulfide
Hydrogen sulfide is flammable and poisonous. Usually it is not a health risk at concentrations present in household water, except in very high concentrations. While such concentrations are rare, hydrogen sulfide's presence in drinking water, when released in confined areas, has been known to cause nausea, illness and, in extreme cases, death.
Water with hydrogen sulfide alone does not cause disease. In rare cases, however, hydrogen sulfide odor may be from sewage pollution which can contain disease-producing contaminants. Therefore, testing for bacterial contamination and Sulfate Reducing Bacteria is highly recommended.
Water Testing
Sulfate
The Option 2 testing kits includes the sulfate test, but for sulfur problems the laboratory must be notified to provide a special container that has a chemical preservative. The testing kits include the sampling instructions, a questionnaire, and information on returning the sample. Hydrogen Sulfide- If this is a problem that the laboratory must be told in advance to provide the necessary sampling container with preservatives. Since hydrogen sulfide is a gas that is dissolved in water and can vaporize (escape) from it, laboratory analysis of hydrogen sulfide in water requires the sample be stabilized immediately following collection. Since the odor may be caused by a number of factors, it is critical that the questionnaire be completed and it is highly recommended that both the basic water quality test with bacteria and a nuisance bacteria kit.
Interpreting Sulfate and Hydrogen Sulfide Test Results
Sulfate
The Environmental Protection Agency (EPA) standards for drinking water fall into two categories -- Primary Standards and Secondary Standards. Primary Standards are based on health considerations and are designed to protect people from three classes of toxic pollutants -- pathogens, radioactive elements, and toxic chemicals. Secondary Standards are based on taste, odor, color, corrosivity, foaming and staining properties of water. Sulfate is classified under the secondary maximum contaminant level (SMCL) standards. The SMCL for sulfate in drinking water is 250 milligrams per liter (mg/l), sometimes expressed as 250 parts per million (ppm).
Hydrogen Sulfide
Although many impurities are regulated by Primary or Secondary Drinking Water Standards set by the EPA, hydrogen sulfide is not regulated because a concentration high enough to be a drinking water health hazard also makes the water unpalatable. The odor of water with as little as 0.5 ppm of hydrogen sulfide concentration is detectable by most people. Concentrations less than 1 ppm give the water a "musty" or "swampy" odor. A 1-2 ppm hydrogen sulfide concentration gives water a "rotten egg" odor and makes the water very corrosive to plumbing. Generally, hydrogen sulfide levels are less than 10 ppm but have been reported as high as 50 to 75 ppm.
Treatment Options
If excessive sulfate or hydrogen sulfide is present in your water supply, you have three basic options:
1) Obtain an alternate water supply, bottled water, or use some type of treatment to remove the impurity. The need for an alternate water supply or should be established before making an investment in treatment equipment or an alternate supply. Based the decision the results of a chemical analysis water, by a reputable laboratory, and after consulting with your physician to help you evaluate the level of risk. It may be possible to obtain a satisfactory alternate water supply by drilling a new well in a different location or a shallower or deeper well in a different aquifer.
2)Another alternate source of water is bottled water that can be purchased in stores or direct from bottling companies. This alternative might be considered especially when the primary concern is water for food preparation and drinking.
3)The typical recommendation is the installation of a whole-house treatment system. The section of the most cost effective system is a function of the overall water quality, the cause of the sulfur odor, and other water treatment issues.
Sulfate Treatment
Several methods of removing sulfate from water are available. The treatment method selected depends on many factors including the level of sulfate in the water, the amount of iron and manganese in the water, and if bacterial contamination also must be treated. The option you choose also depends on how much water you need to treat.
For treating small quantities of water (drinking and cooking only), the typical methods may be distillation or reverse osmosis. The most common method of treating large quantities of water is ion exchange. This process works similar to a water softener. Ion-exchange resin, contained inside the unit, adsorbs sulfate. When the resin is loaded to full capacity with sulfate, treatment ceases. The resin then must be "regenerated" with a salt (sodium chloride) brine solution before further treatment can occur.
Distillation boils water to form steam that is then cooled and then condense the water. Minerals, such as sulfate, do not vaporize with the steam and are left behind in the boiling chamber. Reverse osmosis membranes have a porosity that permits water molecules to pass through but leaves the large ions in solution, i.e., the reject water.
Hydrogen Sulfide
Hydrogen sulfide may be temporarily controlled by conducting a shock chlorination / disinfection of the well or water source. Please visit the Shock Chlorination page to get more information on this protocol. If the problem with the well is because of Sulfate Reducing Bacteria, a high level of chlorination, mixing, and turbulence may be needed.
If hydrogen sulfide odor is associated primarily with the water heating system, a modification to the system may reduce the odor. Replacing the water heater's magnesium corrosion control rod with one made of aluminum or another metal may improve the situation.
To remove low levels of hydrogen sulfide with NO bacterial problems, install an activated carbon filter. The filter must be replaced periodically to maintain performance. Frequency of replacement will depend on daily water use and concentration of hydrogen sulfide in the water.
Hydrogen sulfide concentrations up to about 5 to 7 ppm can be removed using an oxidizing filter. These filters are similar to the units used for iron treatment. This filter contains sand with a manganese dioxide coating that changes hydrogen sulfide gas to tiny particles of sulfur that are trapped inside the filter. The sand filter must be backwashed regularly and treated with potassium permanganate to maintain the coating. Hydrogen sulfide concentrations exceeding 7 to 10 ppm can be removed by injecting an oxidizing chemical such as household bleach or potassium permanganate followed up by filtration. The oxidizing chemical should enter the water upstream from the storage or mixing tank to provide at least 30- 45 minutes of contact time between the chemical and water. The length of the holding time is a function of the chemical dosage, tank configuration, and water temperature. Sulfur particles can then be removed using a sediment filter and the excess chlorine can be removed by activated carbon filtration. When potassium permanganate is used a manganese greensand filter is recommended.
Often the treatment for hydrogen sulfide is the same as for iron and manganese, for more information please visit the iron and manganese webpage. For DIY, water treatment systems for sulfur - we recommend Sulfur Treatment and Control.
Electric Water Heater Treatment (w/o chemicals)
Sulfates and hydrogen sulfide are both common nuisance contaminants. Although neither is usually a significant health hazard, sulfates can have a temporary laxative effect on humans and young livestock. Sulfates also may clog plumbing and stain clothing. Hydrogen sulfide produces an offensive "rotten egg" odor and taste in the water, especially when the water is heated. If the odor is stronger in the electric water heater, we recommend the following:
a. Turn off the system and drain the tank. Note any anomalies, such as: the color and odor of the water, coatings, precipitates, or other solid materials.
b. Allow the tank to refill, but raise the temperature setting of the tank to a level above 140 F.
c. Allow the tank to stay at this level for at least 6 to 10 hours.
d. Turn off the system and reduce system to the normal temperature setting.
e. Drain any discolored water and then allow the tank to refill.
f. If the odor goes away, it was most likely a bacteria growing in the tank that is causing the problem.
g. If the odor returns immediately, it is likely a chemical reaction between the water and the sacrificial anode used in the system. It would be advisable to check the quality of the water entering the tank.
If you have a well, we recommend that you also shock disinfect the well and distribution system. For guidance on disinfecting a water heater, go here. We recommend using Well Sanitizer over chlorine or peroxide.
Treatment options depend on the form and quantities in which sulfates and/or hydrogen sulfide occur in untreated water- Therefore, it is critical that a comprehensive water analysis be conducted. Small quantities of sulfate may be removed from water using distillation or reverse osmosis while large quantities may be removed using ion exchange treatment. Hydrogen sulfide gas may be associated with the presence of Sulfate Reducing Bacteria. Hydrogen sulfide may be reduced or removed by shock chlorination, water heater modification, activated carbon filtration, oxidizing filtration or oxidizing chemical injection. Often treatment for hydrogen sulfide is the same as for iron and manganese, allowing the removal of all three contaminants in one process.
Note: If the cause of the problem is associated with the presence of Iron Reducing Bacteria, Sulfate Reducing Bacteria, and elevated levels of hydrogen sulfide, iron, manganese and other problems. It is critical that the water be tested prior to selecting a treatment system, we recommend the comprehensive water quality test and a nuisance bacteria test (Something from Option 2 and Option 3).
Staining in Dishwasher and Selecting a Detergent
How to Shock Disinfect a Well
Odor Problems, Cause, and Action
Odors in Hot Water and Sulfur (Rotten Egg Odors)
Well Biofouling
Drinking Water Chlorination and Ozone Disinfection/ Oxidation
Water Treatment Sulfur (non-Bacterial Cause)
Online Training Courses
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Engineers Professional Development Hours
Water Treatment, Wastewater Treatment,
and Stormwater Design, Operation, and Management
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Inland Restoration; Wetland Delineation (Basics)
The Training Professionals Portal (Training Portal)
Disinfection By-Products Trihalomethanes
- Details
- Written by Mr. Brian Oram, PG
Water Disinfection Training Course
Continuing Education Courses for Engineers
Trihalomethanes (THM) are a group of four chemicals that are formed along with other disinfection by products when chlorine or other disinfectants used to control microbial contaminants in drinking water react with naturally occurring organic and inorganic matter in water.
The trihalomethanes are chloroform, bromodichloromethane, dibromochloromethane, and bromoform. EPA has published the Stage 1 Disinfectants and Disinfection Byproducts Rule to regulate total trihalomethanes (TTHM) at a maximum allowable annual average level of 80 parts per billion.
The four trihalomethanes (THM's) listed below:
|
Trichloromethane(chloroform) |
CHCl3 |
|
Dibromochloromethane |
CHClBr2 |
|
Bromodichloromethane |
CHCl2Br |
|
Tribromomethane (bromoform) |
CHBr3 |
are all by-products of chlorination. They are Cancer Group B carcinogens (shown to cause cancer in laboratory animals). Trichloromethane (chloroform) is by far the most common in most water systems. Dibromochloromethane is the most serious cancer risk, (0.6 ug/l to cause a 10-6 cancer risk increase) followed in order by Bromoform (4 ug/l), and Chloroform (6 ug/l).
Current regulations limit the concentration of these 4 chemicals added together (total trihalomethane or TTHM levels) to 80 ug/l.
| Bromodichloromethane | Zero (0.6 ppb) |
0.080 mg/L or 80 ppb (Sum of the concentrations of all four trihalomethanes) as an annual average |
| Bromoform | Zero (5 ppb) | |
| Dibromochloromethane | 0.06 mg/L or 60 ppb | |
| Chloroform | 0.07 mg/L or 70 ppb |
Source: http://des.nh.gov/organization/commissioner/pip/factsheets/ard/documents/ard-ehp-13.pdf
Treatment
THM levels tend to increase with pH, temperature, time, and the level of "precursors" present. Precursors are organic material which reacts with chlorine to form THM's. One way to decrease THM's is to eliminate or reduce chlorination before the filters and to reduce precursors.. There are more precursors present before filtration, so we want to reduce or eliminate the time chlorine is in contact with this water. If some oxidation before filtration is required, an alternative disinfectant like potassium permanganate or peroxide could be considered. Note that this may not be an option if prechlorination is necessary to achieve required CT values.
The EPA has indicated that the best available technology for THM control at treatment plants is removal of precursors through "enhanced coagulation". Enhanced coagulation refers to the process of optimizing the filtration process to maximize removal of precursors. Removal is improved by decreasing pH (to levels as low as 4 or 5), increasing the feed rate of coagulants, and possibly using ferric coagulants instead of alum.
For point of use systems at homes, activated carbon filters are the most effective treatment. Reverse osmosis units will also eliminate trihalomethanes.
Regulations - They are In !
The EPA is considering extensive revisions to the regulations covering disinfection by-products (DBP's). The limit for TTHM's would be lowered to 80 ug/l, and three additional categories of DBP's . This standard will replace the current standard of a maximum allowable annual average level of 100 parts per billion in December 2001 for large surface water public water systems. The standard will become effective for the first time in December 2003 for small surface water and all ground water systems
Haloacetic acids (monobromoacetic acid, dibromoacetic acid, monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid) are byproducts of chlorination similar to THM's. An MCL for total haloacetic acids of 60 ug/l is expected. Excessive levels can cause nervous system and liver effects.
Chlorite is to be regulated with an MCL set at 1 mg/l. Excessive levels can cause hemolytic anemia.
Bromate, the other newly regulated DBP , is a concern only for systems using ozone. An MCL of 10 ug/l is expected. Excessive levels causes gastrointestinal, kidney, and hearing effects.
Learn more about water treatment system design.
More Comprehensive Information on Trihalomethanes
University of Florida
http://www.fwrj.com/techarticles/0410%20FWRJ_tech1.pdf
Canadian Website
http://www.env.gov.nl.ca/env/faq/thm_facts.html
Water Quality Help Guides
Glossary of Water Terminology
Water Treatment System to Management
Trihalomethanes in Your Household Water
Note: ug/l is used as an abbreviation for micrograms/liter or parts per billion.
Note: THM's are not a major concern for treating groundwater wells with low organic matter content, but it may be a problem after a shock disinfection. Arsenic may also be a problem after a shock disinfection. THM's form through the partial oxidation of organic material, therefore it is a more important concern to treating surfacewater and/or springs that have a high organic matter content.
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Sulfate, Hydrogen Sulfide, Sulfate Reducing Bacteria - How to Identify and Manage
- Details
- Written by Mr. Brian Oram, PG
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Shock Well and System Disinfection - Short Term and Potential Long-Term Solution
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Two forms of sulfur are commonly found in drinking water supplies: sulfate and hydrogen sulfide. Both forms are nuisances that usually do not pose a health risk at the concentrations found in domestic water supplies.
Sulfates and Hydrogen Sulfide
Sulfates are a combination of sulfur and oxygen and are a part of naturally occurring minerals in some soil and rock formations that contain groundwater. The mineral dissolves over time and is released into groundwater.
Sulfur-reducing bacteria, which use sulfur as an energy source, are the primary producers of large quantities of hydrogen sulfide. These bacteria chemically change natural sulfates in water to hydrogen sulfide. Sulfur-reducing bacteria live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners and water heaters. These bacteria usually flourish on the hot water side of a water distribution system.
Hydrogen sulfide gas also occurs naturally in some groundwater. It is formed from decomposing underground deposits of organic matter such as decaying plant material. It is found in deep or shallow wells and also can enter surface water through springs, although it quickly escapes to the atmosphere. Hydrogen sulfide often is present in wells drilled in shale or sandstone, or near coal or peat deposits or oil fields.
Occasionally, a hot water heater is a source of hydrogen sulfide odor. The magnesium corrosion control rod present in many hot water heaters can chemically reduce naturally occurring sulfates to hydrogen sulfide.
Sulfate
Sulfate minerals can cause scale buildup in water pipes similar to other minerals and may be associated with a bitter taste in water that can have a laxative effect on humans and young livestock. Elevated sulfate levels in combination with chlorine bleach can make cleaning clothes difficult. Sulfur-oxidizing bacteria produce effects similar to those of iron bacteria. They convert sulfide into sulfate, producing a dark slime that can clog plumbing and/or stain clothing. Blackening of water or dark slime coating the inside of toilet tanks may indicate a sulfur-oxidizing bacteria problem. Sulfur-oxidizing bacteria are less common than sulfur-reducing bacteria.
Hydrogen Sulfide
Hydrogen sulfide gas produces an offensive "rotten egg" or "sulfur water" odor and taste in the water. In some cases, the odor may be noticeable only when the water is initially turned on or when hot water is run. Heat forces the gas into the air which may cause the odor to be especially offensive in a shower. Occasionally, a hot water heater is a source of hydrogen sulfide odor. The magnesium corrosion control rod present in many hot water heaters can chemically reduce naturally occurring sulfates to hydrogen sulfide.
A nuisance associated with hydrogen sulfide includes its corrosiveness to metals such as iron, steel, copper and brass. It can tarnish silverware and discolor copper and brass utensils. Hydrogen sulfide also can cause yellow or black stains on kitchen and bathroom fixtures. Coffee, tea and other beverages made with water containing hydrogen sulfide may be discolored and the appearance and taste of cooked foods can be affected.
High concentrations of dissolved hydrogen sulfide also can foul the resin bed of an ion exchange water softener. When a hydrogen sulfide odor occurs in treated water (softened or filtered) and no hydrogen sulfide is detected in the non-treated water, it usually indicates the presence of some form of sulfate-reducing bacteria in the system. Water softeners provide a convenient environment for these bacteria to grow. A "salt-loving" bacteria, that uses sulfates as an energy source, may produce a black slime inside water softeners.
Health Issues
Sulfate
Sulfate may have a laxative effect that can lead to dehydration and is of special concern for infants. With time, people and young livestock will become acclimated to the sulfate and the symptoms disappear. Sulfur-oxidizing bacteria pose no known human health risk. The Maximum contaminate level is 250 mg/L.
Hydrogen Sulfide
Hydrogen sulfide is flammable and poisonous. Usually it is not a health risk at concentrations present in household water, except in very high concentrations. While such concentrations are rare, hydrogen sulfide's presence in drinking water when released in confined areas has been known to cause nausea, illness and, in extreme cases, death. Water with hydrogen sulfide alone does not cause disease. In rare cases, however, hydrogen sulfide odor may be from sewage pollution which can contain disease-producing contaminants. Therefore, testing for bacterial contamination and Sulfate Reducing Bacteria is highly recommended.
Testing Options
Sulfate
The Option 1 testing kit includes the sulfate test, but for sulfur problems the laboratory must be notified to provide a special container that has a chemical preservative. The testing kits include the sampling instructions, a questionnaire, and information on returning the sample. Hydrogen Sulfide- If this is a problem that laboratory must be told in advance to provide the necessary sampling container with preservatives.
Since hydrogen sulfide is a gas that is dissolved in water and can vaporize (escape) from it, laboratory analysis of hydrogen sulfide in water requires the sample be stabilized immediately following collection. Since the odor may be caused by a number of factors, it is critical that the questionnaire be completed and it is highly recommended that both the Option 1 and Option 3 water testing packages are conducted..
Drinking Water Standards
Sulfate
The Environmental Protection Agency (EPA) standards for drinking water fall into two categories -- Primary Standards and Secondary Standards. Primary Standards are based on health considerations and are designed to protect people from three classes of toxic pollutants -- pathogens, radioactive elements and toxic chemicals. Secondary Standards are based on taste, odor, color, corrosivity, foaming and staining properties of water. Sulfate is classified under the secondary maximum contaminant level (SMCL) standards. The SMCL for sulfate in drinking water is 250 milligrams per liter (mg/l), sometimes expressed as 250 parts per million (ppm).
Hydrogen Sulfide
Although many impurities are regulated by Primary or Secondary Drinking Water Standards set by the EPA, hydrogen sulfide is not regulated because a concentration high enough to be a drinking water health hazard also makes the water unpalatable. The odor of water with as little as 0.5 ppm of hydrogen sulfide concentration is detectable by most people. Concentrations less than 1 ppm give the water a "musty" or "swampy" odor. A 1-2 ppm hydrogen sulfide concentration gives water a "rotten egg" odor and makes the water very corrosive to plumbing. Generally, hydrogen sulfide levels are less than 10 ppm, but have been reported as high as 50 to 75 ppm.
The Options
If excessive sulfate or hydrogen sulfide is present in your water supply, you have three basic options:
1) Obtain an alternate water supply, bottled water, or use some type of treatment to remove the impurity. The need for an alternate water supply or should be established before making an investment in treatment equipment or an alternate supply. Based the decision the results of a chemical analysis water, by a reputable laboratory, and after consulting with your physician to help you evaluate the level of risk. It may be possible to obtain a satisfactory alternate water supply by drilling a new well in a different location or a shallower or deeper well in a different aquifer.
2)Another alternate source of water is bottled water that can be purchased in stores or direct from bottling companies. This alternative might be considered especially when the primary concern is water for food preparation and drinking.
3)The typical recommendation is the installation of a whole-house treatment system. The section of the most cost effective system is a function of the overall water quality, cause of the sulfur odor, and other water treatment issues.
Sulfate Treatment
Several methods of removing sulfate from water are available. The treatment method selected depends on many factors including the level of sulfate in the water, the amount of iron and manganese in the water, and if bacterial contamination also must be treated. The option you choose also depends on how much water you need to treat.
For treating small quantities of water (drinking and cooking only) the typical methods may be distillation or reverse osmosis. The most common method of treating large quantities of water is ion exchange. This process works similar to a water softener. Ion-exchange resin, contained inside the unit, adsorbs sulfate. When the resin is loaded to full capacity with sulfate, treatment ceases. The resin then must be "regenerated" with a salt (sodium chloride) brine solution before further treatment can occur.
Distillation boils water to form steam that is then cooled and then recondense the water. Minerals, such as sulfate, do not vaporize with the steam and are left behind in the boiling chamber. Reverse osmosis membranes have a porosity that permits water molecules to pass through but leaves the large ions in solution.
Hydrogen Sulfide
Hydrogen sulfide may be temporarily controlled by conducting a shock chlorination / disinfection of the well or water source. Please visit the Shock Chlorination page to get more information on this protocol. If the problem with the well is because of Sulfate Reducing Bacteria, a high level of chlorination, mixing, and turbulence may be needed.
If hydrogen sulfide odor is associated primarily with the hot water system, a hot water heater modification may reduce the odor. Replacing the water heater's magnesium corrosion control rod with one made of aluminum or another metal may improve the situation.
To remove low levels of hydrogen sulfide, install an activated carbon filter. The filter must be replaced periodically to maintain performance. Frequency of replacement will depend on daily water use and concentration of hydrogen sulfide in the water.
Hydrogen sulfide concentrations up to about 5 to 7 ppm can be removed using an oxidizing filter. These filters are similar to the units used for iron treatment . This filter contains sand with a manganese dioxide coating that changes hydrogen sulfide gas to tiny particles of sulfur that are trapped inside the filter. The sand filter must be backwashed regularly and treated with potassium permanganate to maintain the coating. Hydrogen sulfide concentrations exceeding 7 to 10 ppm can be removed by injecting an oxidizing chemical such as household bleach or potassium permanganate followed up by filtration. The oxidizing chemical should enter the water upstream from the storage or mixing tank to provide at least 30- 45 minutes of contact time between the chemical and water. The length of the holding time is a function of the chemical dosage, tank configuration, and water temperature. Sulfur particles can then be removed using a sediment filter and the excess chlorine can be removed by activated carbon filtration. When potassium permanganate is used a manganese greensand filter is recommended.
Often the treatment for hydrogen sulfide is the same as for iron and manganese, for more information please visit the iron and manganese webpage.
Nuisance Problems
Sulfates and hydrogen sulfide are both common nuisance contaminants. Although neither is usually a significant health hazard, sulfates can have a temporary laxative effect on humans and young livestock. Sulfates also may clog plumbing and stain clothing. Hydrogen sulfide produces an offensive "rotten egg" odor and taste in the water, especially when the water is heated. If the odor is stronger in the hot water, we recommend the following:
a. Turn off the system and drain the tank. Note any anolomies, such as: the color and odor of the water, coatings, precipitates, or other solid materials.
b. Allow the tank to refill, but raise the temperature setting of the tank to a level above 140 F.
c. Allow the tank to stay at this level for at least 6 to 10 hours.
d. Turn off the system and reduce system to the normal temperature setting.
e. Drain any discolored water and then allow the tank to refill.
f. If the odor goes away, it was most likely a bacteria growing in the tank that is causing the problem.
g. If the odor returns immediately, it is likely a chemical reaction between the water and the sacrifical anode used in the system. It would be advisable to check the quality of the entering the tank.
If you have a well, we recommend that you also shock disinfect the well and distribution system. For guidance on disinfecting a water heater, go here.
Treatment options depend on the form and quantities in which sulfates and/or hydrogen sulfide occur in untreated water- Therefore, it is critical that a comprehensive water analysis be conducted.. Small quantities of sulfate may be removed from water using distillation or reverse osmosis, while large quantities may be removed using ion exchange treatment. Hydrogen sulfide gas may be associated with the presence of Sulfate Reducing Bacteria. Hydrogen sulfide may be reduced or removed by shock chlorination, water heater modification, activated carbon filtration, oxidizing filtration or oxidizing chemical injection. Often treatment for hydrogen sulfide is the same as for iron and manganese, allowing the removal of all three contaminants in one process.
Note: If the cause of the problem is associated with the presence of Iron Reducing Bacteria, Sulfate Reducing Bacteria, and elevated levels of hydrogen sulfide, iron, manganese and other problems. It is critical that the water be tested prior to selecting a treatment system, we recommend the Water Testing . Also, if you plan to shock disinfect your well or distribution system - we recommend using Sanitizing Pellets (Well Safe) over bleach.
Staining in Dishwasher and Selecting a Detergent
How to Shock Disinfect a Well
Odor Problems, Cause, and Action
Odors in Hotwater and Sulfur (Rotten Egg Odors)
Well Biofouling
Treatment for Sulfur Odors (No Bacterial Origin)
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