Public Information Pamphlet #10
Bacteria and Water Wells

Contents:

1. Introduction: What Is The Issue?
2. Importance of Well Water
• Ground Water in the United States
• Value of Ground Water
3. Microorganisms in Ground Water
• Bacteria Background
• Microorganisms
• Viruses and Protozoa
• Coliform Bacteria
• Iron Bacteria
4. Well Protection Strategies
• How Can Bacteria Get Into the Well
• How to Test for Bacteria
• How to Sample Well Water for a Bacteria Test
• What do the Test Results Mean?
• Description of Well Water Disinfection Procedure
5. Treatment Techniques
• Filters
• Chlorine
• Iodine
• Ultraviolet Light
• Ozone
6. Where to Go for Advice

1. Introduction: What Is The Issue?

        Bacteria may cause sickness. Bacteria and Water Wells provides the public with information and guidance about what steps should be taken if bacteria are present in a water well. This pamphlet is principally aimed at consumers using private wells as a water source. Homeowners have the responsibility to check the water quality of their private wells. This publication gives background information about bacteria, treatment techniques and aquifer and water well protection strategies. For many people, the word bacteria brings immediate images of disease and sickness. The good news is that not all bacteria are harmful. There are bacteria everywhere; in the air, in the soil, in your mouth, millions in a spoonful of yogurt!

        The occurrence of bacteria in water is common, treatable, and in most cases, preventable. The ideal situation is to have no bacteria in drinking water, although most bacteria in water wells are harmless and pose little health risk. Ground water in the majority of properly constructed drilled wells is bacteria free. To ensure protection from any health risk, it is important for the public to understand something about microorganisms and how they may impact health. The information in this pamphlet is a first step to help in the education process.

2. Importance of Well Water

Ground Water Use in the United States

        Over 130 million Americans use ground water for drinking every day. About 40 million people obtain ground water from 15 million private wells. Every day in the U.S., about 2,000 new wells are constructed for water supply. Most town and community water supply systems are checked by professional staff who are required by law to ensure that the water supplied to homes is safe for drinking. It is the responsibility of homeowners to keep self-supplied well water free from health risk.

        There is a difference between well contamination and aquifer contamination. If a bacterial water quality problem is detected, it could be occurring in the water system, the well or (less likely), the aquifer. You need to find out where the problem is located. There is no point in investing money to permanently treat symptoms if it is possible to eliminate the cause.

Value of Ground Water

        In the 1950's and 1960's, most U.S. communities gave greater attention to more visible services, such as fire protection, than to the less dramatic issue of aquifer protection. However, by the 1980's and 1990's, increased suburban population densities, competing economic and environmental demands for water resources, increased environmental awareness, and concern with health related issues, have made the public far more aware of the importance of safe drinking water. Safe water cannot be taken for granted. While there has been a change in awareness, many people are still prepared to pay more for cable TV than they are prepared to pay for safe drinking water!

3. Microorganisms in Ground Water

Bacteria Background

        Bacteria are microscopic organisms. They are so tiny that about 25,000 lined up would take up about three inches. [Just one, is correctly called a bacterium, but they are usually referred to in the plural, bacteria.] Bacteria have existed for a very long time. There are micro-fossils in the geologic record that show bacteria were in existence 3.2 billion years ago. Some researchers believe that the first oxygen that appeared on Earth, 2 billion years ago, was created by bacteria.

        Antony van Leeuwenhoek is credited with discovering bacteria in 1676. The big question then was, where did they come from? Two hundred years later, in 1876, Robert Koch concluded that bacteria can cause disease. Louis Pasteur's work with bacteria showed that vaccination was a way to acquire immunity from some diseases.

        Bacteria have great diversity. Some grow and multiply by using energy obtained from sulfur, ammonia, hydrogen or iron, and they obtain carbon for cell synthesis from carbon dioxide. Some bacteria thrive in oxygen rich environments (aerobic) and others in oxygen deficient (anaerobic) conditions. Most bacteria reproduce by binary fission (split into two). If conditions are suitable, bacteria can reproduce very quickly. They are very resilient, remaining dormant when conditions are not ideal. Dried, but living bacteria can even be carried in the air. Bacteria can excrete toxins or carry them inside their cell wall until they die and disintegrate. Some bacteria may invade a specific organ of the body, for example the brain, throat or bone. Bacteria may produce enzymes that are responsible for illness.

        Not all bacteria cause disease and harm living creatures; some can be very beneficial. Bacteria are the beginning of the world's food chain, and as decomposers, bacteria play a critical role in recycling organic materials essential to plants and animals. Great numbers of bacteria live on human skin surfaces; there are millions in one drop of saliva. Bacteria are an essential part of the digestive process of animals and insects. Laboratory grown bacteria "superbugs" have proved to be useful in cleaning up environmental contamination. Septic systems and most waste water treatment facilities are designed to allow the work of bacteria to naturally break down harmful components.

Microorganisms

        Many types of microbes live naturally in soil and rock environments and are part of the sub-surface ecosystem. Sub-surface dwelling organisms are usually attached to the rock particles in soils and aquifers. During periods of high water table, for example after prolonged rainfall, ground water has greater contact with soil organisms and nutrients. The result can be an increase in organisms found in water from wells.

        All natural water (rivers, lakes, wetlands) contain micro-organisms. Ground water usually has many fewer microorganisms than surface water because of its long travel time in the sub-surface environment. However, ground water can become contaminated by domestic sewage, feedlots and surface runoff, as well as other pollution sources. Where the subsurface geology permits rapid downward movement of water from the surface, or where the ground water sources are tapped near the surface, aquifers may be vulnerable. Shallow dug wells, or drilled wells in which the well casing is not properly grouted (sealed), are particularly susceptible to contamination. Some types of bacteria can cause a nasty taste and odor, or cause cloudiness in water.

Viruses and Protozoa

        In addition to bacteria, two other types of pathogenic organisms can affect water quality, viruses and protozoa. The disease causing organisms usually leave an infected person via feces. They may cause illness in anyone drinking the contaminated water, although many people do not experience any adverse effects. Bacteriologic and protozoic pathogens are known to cause typhoid, dysentery, cholera, and some types of gastroenteritis. Giardia lamblia and Cryptosporidium are protozoal parasites that can cause health problems. Fortunately, occurrences of these are rare in ground water because the relatively large size of the protozoa cysts allows them to be filtered out as water soaks through the soil to the water table. Viruses account for more than 100 human diseases including polio, infectious hepatitis and some forms of gastroenteritis.

Coliform Bacteria

        Coliform bacteria is the bacteria most commonly associated with water quality. The Environmental Protection Agency standard for acceptable drinking water is a total coliform count of zero. Coliform bacteria are a large group of various species of bacteria. The group includes bacteria that occur naturally in the intestines of warm-blooded animals (fecal coliform) and non-fecal coliform bacteria. Fecal coliforms can include disease causing and non-disease causing species.

        Escherichia coli (E. coli), often listed in water quality analyses, is one species of fecal coliform bacteria. They occur in the digestive system of healthy warm-blooded animals. E. coli are present in large numbers in human sewage. E. coli can be easily cultured in a laboratory and therefore, they are a good indicator species. Its presence in a water sample indicates that sewage material may be present and that if sewage is present, more harmful disease causing organisms may also be present.

Iron Bacteria

        Some bacteria that occur in wells, while not themselves harmful, can cause problems. Iron bacteria can cause staining of plumbing fittings and laundry, can provide a place in wells for other bacteria to live, can increase corrosion and can cause encrustation of well screens and pumps. Iron and sulfur bacteria cause a build up of a bio-film in wells. By providing an environment for other more harmful bacteria to live, the slime reduces the ability of chlorine to kill bacteria. Another negative effect of iron bacteria is that they can cause electrons from ferrous iron (Fe2) to be converted to ferric iron (Fe3). This results in increased oxidation (corrosion) of pipes and pumps. An additional problem is that the free ferric iron ion can bind with other chemicals to cause clogging of pump intakes, well screens and water filters. A reduction in the inflow spaces to a well will cause an increase in speed of water flow in the remaining spaces; this turbulent flow causes the release of even more minerals to clog the well and water system.

4. Well Protection Strategies

How Can Bacteria Get into a Well?

        A properly constructed and adequately cased (lined) and grouted (sealed) water well usually obtains its water at a depth at which bacteria are no longer present. Bacteria are usually filtered out, or they die off, as water infiltrates and slowly moves in the sub-surface ground water environment. However, bacteria can invade ground water when there is insufficient filtration or travel time between the land surface and the ground water.

        Bacteria are found in upper soil layers and in most streams, lakes and ponds; in addition, there can be concentrated bacteria sources such as inefficient septic systems, farm animals and storm runoff. There are several ways in which bacteria actually get into a well:

• Any shallow or dug well that is constructed from boards,  bricks, stone or tile is vulnerable to surface water  contamination. Dug wells, with their water in contact  with saturated soil layers, are particularly at risk  because bacteria affected water can seep straight into  the well. Insect infestation is very difficult to prevent  in large diameter wells.
• If a drilled or bored well has casing (liner) that has  not been properly sealed, bacteria from the upper soil  layers may "leak" down into the well. In such  cases, surface water or contaminated ground water may  move vertically downward contaminating high quality  aquifers.
• In the event of a flood or storm runoff, surface water  could enter the top of the well if the casing does not extend far enough above the ground or if there is no  watertight seal on the well casing. Wells that are in  pits below ground level, in driveways or lawns, may be  especially vulnerable to such pounding.
• Over time, old well casings may rust through, leaving  holes near the ground surface where water can seep in and  contaminate deeper ground water. This problem can be made  worse if a water well is used as an earth contact for  electricity. Earthing causes well casing corrosion.  Although convenient for electricians, well casing should  not be used as an electrical ground.
• Well casing can become cracked. Once there is a direct  connection to the surface layers, bacterial infection may  result. Earthquakes, subsidence and settling around the  well, or impact damage from farm implements or snow  plows, can make a well susceptible to contamination.
• Well bacteria can be introduced into a well when it is  drilled, or when a pump is installed or serviced.  Contractors must ensure that their equipment is  decontaminated between jobs to prevent transporting  infection from well to well. Pump installers often lay  the pump, pipe and cable out on the ground before  installation in the well. This practice is unwise because  it can allow bacteria from the ground surface to adhere  to the well equipment and enter the well. Water wells  should be sanitized after any service or installation  work.
• Wells may become infected when ground water levels rise  above normal and extend up to soil levels where bacteria  are present. This can occur (1) in times of exceptional  rainfall, (2) if major long-term water use by a nearby  irrigation or municipal well ceases [ground water levels  then begin to rise much higher than at the time of  original well construction], or (3) when road  construction, mining operations or dam construction lead  to water level changes in wells.

• A common bacteria-causing problem is a faulty (or  non-existent!) well seal that allows insects, especially  earwig beetles, to take up residence in well casing.  Their droppings and dead bodies can cause bacterial  contamination of wells.
• Unsealed abandoned water wells and geotechnical  investigation drill holes (typically used in engineering  investigations for highways and major building  development) can be conduits for bacteriologically  affected surface water to reach aquifers. All landowners  should be aware of the potential risks of old unused  wells. Natural surface outcrops of fractured rock and  areas of mining or quarrying can also provide rapid  access of contaminated surface water to aquifers.
• Backflow prevention devices are essential to prevent any  risk of bacteria being siphoned back in the well. An  example of this problem could occur if a power failure  stopped a pump while a garden hose was filling a fish  pond. Without a backflow device, or an adequate foot  valve on the pump, water from the fish pond could be  siphoned back down the well. Back flow prevention devices  are easily fitted and are not expensive.

How to Test for Bacteria

        All new water wells should be tested for the presence of bacteria. All wells used for drinking should be rechecked annually or after any maintenance or replacement work that has involved well equipment. It is particularly important to test a well if at any time, change in taste, odor or appearance of the water is noticed.

        Reliable do-it-yourself bacteria testing kits are now on the market for about $15. It is important to follow directions. A bacteriological analysis by a certified laboratory usually costs between $30 and $40. Sample bottles (and instructions) are available from virtually all certified water quality labs. If a technician visits your home to collect the sample, the testing fee is likely to be higher. Testing services may also be available from county health departments or from state agencies (see listing of state phone numbers.)

How to Sample Well Water for a Bacteria Test

        This is a general guide only; carefully follow laboratory instructions or the directions on a store-bought test kit:

1. obtain sterile bottle
2. remove aeration devices from the cold water tap/spigot/  faucet
3. run cold water for three minutes at full flow
4. reduce flow to a trickle and run for another minute
5. open the sterile sample bottle (do NOT touch the inside  of the bottle or lid)
6. do NOT rinse the bottle
7. fill the bottle as directed, ( about 200ml or 1/4 pint)
8. put cap on bottle, seal tightly
9. put your name, address, date and time of sampling in the  bottle
10. keep bottle cool
11. deliver immediately to lab, as required for their  schedule, best within 24 hours (some labs don't take  samples on Fridays).

        Sample as close to the well as possible; there may be a tap in the basement. Most quality analyses are done to test the well water. It is possible that the well is clear of the bacteria, and that an inadequately maintained treatment system (especially point of use systems) may be harboring bacteria. A test on a sample from the kitchen tap may be needed. To test the water quality in a point of use filter, take a sample first thing in the morning - do not run the water before sampling.

What Do the Test Results Mean?

        A bacteriological test shows that coliform bacteria were (or were not) in the water sample delivered to the lab. A sample that is reported "safe bacteriologically," means that coliform were not found in the sample. If the sample was taken according to directions, you can be reasonably sure that the water is suitable for drinking and general domestic use. When a sample is reported "unsafe bacteriologically," it means that coliform bacteria were found. The chances are that the well has been affected by surface water or near-surface waters. To be on the safe side, consider the water supply to be a health risk and until you have found out where the problem originates, you should not consume the water unless it is boiled first.

        The first thing to do with an "unsafe" result is to re-sample. If the second sample results show presence of coliform bacteria, you need to immediately investigate sources of contamination and disinfect your water system. Unless you feel confident about doing this yourself, the well should be disinfected by a qualified sanitarian, or ground water contractor. Guidelines for well disinfection procedure are given below.

        If the contamination is just in the well or water system, it should be removed by the disinfection process. It can sometimes take two or three disinfection attempts before the bacteria are eliminated.

        In some wells, bacteria levels may slowly return, and an annual "shock" disinfection may be needed to keep the problem under control. If the problem is related to a damaged well, the well needs to be fixed. If there is an obvious nearby contamination source, the problem needs to be resolved. Tracing the cause may need systematic detective work to eliminate potential causes.

        BEFORE investing in water treatment equipment, it is recommended that all attempts be made to solve the problem by sanitizing the well, ensuring that the well construction is in good order and that nearby potential contamination sources are removed. Some states will not approve wells that need treatment to remove bacteria.

Description of Water Well Disinfection Procedure

        This is a general description only; state and county codes may vary.

        Wells are most economically disinfected by using a chlorine and water mixture. The best source is dry granulated chlorine, but this can be DANGEROUS to use and is NOT recommended for home owner use. A safer and more convenient source of chlorine for do-it-yourself disinfection is household laundry bleach. Bleach should not be put into the well straight from the bottle. The general recommendation is to dilute the laundry bleach 1:100, (one gallon of bleach to 100 gallons or water; half a gallon of bleach to 50 gallons of water; a quart of bleach to 25 gallons of water.) [Although almost any brand of laundry bleach may be used, some states recommend specific products. Some manufacturers of laundry bleach state that their product is formulated for laundry use and that it has not been made for any other purposes.]

        For a 6" diameter well (the usual household well size), 15 gallons of (chlorine + water) solution are needed for every 10 feet of well depth (depth of well below water level). For example, a 200 ft. deep, 6" diameter well, will need 300 gallons of mixture. Three gallons of household laundry bleach should be enough, mixed at a 1 to 100 ratio with water. A new clean garbage can holds about 25 gallons.

• A 4 inch diameter well needs 7 gallons of chlorine + water mixture for each 10 feet.
  
• An 8 inch diameter well needs 26 gallons of chlorine + water mixture for each 10 feet.

        For a large diameter well a bit of elementary math will be needed to work out the volume of bleach mixture required.

        Remove the well cap and pour the chlorine and water solution into the well. If a 25 gallon container is used, it will probably be necessary to mix and pour several times to get the right volume of chlorine and water mixture into the well.

        Once all the chlorine mixture is in the well, use a hose connected to the home system being chlorinated and run water back down the well for at least 15 to 20 minutes. This will ensure that the chlorinated water is being circulated. At this time, make sure that the hose is used to thoroughly rinse down the sides of the well casing above water level.

        In some low yielding wells that are really encrusted, the well casing may "fill-up" as you add the mixture. You will need to take a longer time in adding the mixture. [It may be necessary to remove the pump and rehabilitate the well to regain the original yield. This will have to done by a contractor.]

        Run each of the water taps in the house (hot & cold and those to the washing machine and dish washer) until there is a smell of chlorine, then turn the tap off. Leave the chlorinated water in the system, (well and plumbing) for 12 to 24 hours. This will disinfect the whole water system. Turn off the water heater during this time. If you don't have a good sense of smell, the use of a swimming pool chlorine test kit can show whether or not there is chlorinated throughout the plumbing system.

        Remove all the chlorinated water from the well by running the pump and leading the hose to a"safe" area. Do not put the chlorine solution into a septic system. Do not put it in a creek where it could kill fish. Do not put it onto a flower or vegetable garden because it can kill plants. Check with the authorities before putting it into a municipal sewer. At a 1 to 100 concentration, the small amount left in house plumbing system can safely be put down the drain.

        Run the system until all smell of chlorine is gone. Sample the well a day or two later and retest the water.

5. Treatment Techniques

        Bacteria are most effectively eliminated from drinking water by chlorine disinfection, filtration, ultraviolet irradiation or ozonation. All of the methods require careful attention to equipment selection. Buying an over-designed system will not necessarily provide any better protection. Make sure that the water equipment salesperson is knowledgeable and that the company specializes in water treatment. Some water treatment specialists may not be familiar with all the latest technologies and treatment equipment options. Always obtain cost quotations from more than one company and always have your water analysis done by an independent laboratory. Some bacteria treatment devices do not work properly if certain minerals are present. Water treatment is not a "one size fits all" operation. Once installed, it is very important to adhere to the equipment maintenance schedule.

Filters

        Filtration cannot readily remove bacteria or viruses from drinking water. Fine filtration can be a very effective means of straining out large organisms like protozoan cysts and worm eggs, but it needs to be complimented with a disinfection method to eliminate bacteria. Some filtration devices at the level of 0.25 microns absolute, and finer, may be effective for bacteria removal but may also cause reduction in water pressure. Filters must be checked and changed regularly.

Chlorine

        Disinfectant-dispersing equipment should be automatic, require minimal maintenance and treat all water entering the home. It should also be fail-safe so that it is not possible to unknowingly use or consume untreated water. There are many devices available for dispensing doses of chlorine. Some operate by releasing pellets into the well, others inject a chlorine solution into the water line.

        Chlorine is the most widely used method in the United States for disinfecting municipal and individual water supplies. It destroys bacteria by oxidizing their internal enzymes. However, if water has a high organic level, dangerous chlorinated organics (trihalomethanes) can be produced. Some of these chlorinated organic chemicals are suspected of being carcinogenic to humans. Chlorination systems need to be checked and maintained regularly by the homeowners.

Iodine

        Iodine is chemically more stable than chlorine but more expensive. Iodination equipment is usually installed between the pump and holding or pressure tank, and a precisely measured continuous flow of concentrated iodine is fed into the water pipe. This type of equipment is simple to operate and requires little maintenance. Iodine can impart a slight taste to the water.

Ultraviolet Light

        Ultraviolet irradiation will kill bacteria by creating photochemical changes in its DNA. No chemicals are added to the water by this process. Most ultraviolet water treatment units consist of one or more ultraviolet lamps usually enclosed in a quartz sleeve, around which the water flows. The UV lamps are similar to fluorescent lamps and the quartz sleeve surrounding each lamp protects the lamp from the cooling action of water. The killing effect of the lamp is reduced when the lamp temperature is lowered. Ground water is usually a constant temperature year round and so it is possible to set a flow rate that will not lead to excess cooling.

        The effectiveness of UV irradiation depends on the intensity of the light, depth of exposure and contact time. Water passes in a relatively thin layer around the lamp; therefore, water flow must be regulated to ensure that all organisms receive adequate exposure. If the water is at all turbid, or if it contains traces of iron, the effectiveness of UV is greatly reduced. In such cases, the water needs to be filtered before it reaches the UV system.

        Ultraviolet irradiation units are automatic and require little maintenance. There are several commercially available UV systems designed for home wells.

Ozone

        Ozone contains three oxygen atoms. It has been used in water treatment since 1903. It is more effective against bacteria and viruses than chlorine and adds no chemicals to the water. Ozone cannot be stored and requires an on-site ozone generator. In general, ozonation equipment and operating costs are higher than other treatment procedures.

6. Where to Go for Advice

        The American Ground Water Trust can provide a contact telephone number in each state for well drillers who are members of their professional state ground water or water well association. Call the Trust at (603) 228-5444. The Trust can also assist with contacts in state agencies and can provide information about the availability of Bacteria Test Kits. The Trust's mission is to assist the public and communities with information about ground water. See the back cover of this pamphlet for more information about the American Ground Water Trust.

        County Health Departments have trained staff who can provide advice to consumers and homeowners about water quality issues. Many county level departments and agencies have useful information about wells, water quality and aquifer protection. Agricultural Extension Service personnel also provide information. Most telephone directories list such services.

        Contractors are local experts who can usually provide practical insight to questions concerning water well quality. The Yellow Pages will list well drillers, pump installers and treatment specialists in your area. Select contractors who are licensed, registered, and who have declared a membership commitment to the mission and ideals of their state and national trade associations.

        State Agencies and Departments have staff to help with citizen inquiries. The state list below includes the number to call for inquiries about well bacteria. Just about every state has a different agency or department. Most will provide information and advice to the public. You may have to be patient as you negotiate state agency telephone switchboards and voice mail! After your initial call, you may be referred to a specific office or laboratory that deals with your area.

State List of Telephone Numbers for Well Bacteria Inquiries

Abbreviations used in table

        The information in this table was obtained in spring 1996. State agency responsibilities may change. You may be referred to a different department or local office.

Other sources of information and advice:

• EPA Drinking Water Hotline (800) 426-4791 (Washington,  D.C.). The EPA provides general information about Federal  Drinking Water regulations and guidelines.
• Water Quality Association (630) 505-0160 (Illinois). The  WQA maintains a register of information on the  effectiveness of commercially available water treatment  equipment.
• National Ground Water Association (614) 337-1949 (Ohio).  The NGWA is a 23,000 member international organization  representing all professions of the ground water  industry.
• Center for Disease Control and Prevention (404) 639-2206  (Atlanta). Federal center of expertise.

Don't forget local sources of information:

• Libraries. Most libraries have information in their  reference sections that can provide background about  bacteria.
• Colleges and Universities. At universities and colleges  that focus on water resources, environmental engineering  or community health issues, research and teaching faculty  members may have useful information related to aquifer  protection, water wells and water treatment.

American Ground Water Trust

        The American Ground Water Trust is a 501(c)3 non-profit membership organization. The mission of the Trust is to protect America's ground water, promote public awareness of the environmental and economic importance of ground water and provide accurate information to assist public participation in water resources decisions.

• Join the American Ground Water Trust to learn more about  how you can protect your ground water.
• Contact the Trust about ground water issues and concerns  in your town, region or state. The Trust will respond  effectively to your questions and recommend a course of  action.
• Volunteer to help with educational programs and special  events in your area.
• Request a list of Trust Educational Products.

American Ground Water Trust
16 Centre Street
Concord, New Hampshire 03301
Tel (603) 228-5444 Fax (603) 228-6557
E-mail TrustInfo@agwt.org

        Information in this pamphlet is provided in good faith to inform the public about ground water and ground water related issues. In all cases, the Trust urges consumers to contact local experts, and where appropriate, to refer to local codes, rules, regulations and laws.