SUB-PROBLEMS INCLUDING LEADING TO IMPAIRMENT AND BEST PRACTICES FOR PRIVATE DRINKING WATER SYSTEMS
Approximately 15% of the people of the United States utilize private drinking water wells as their water supply. Local and state rules and regulations are utilized to try to control the potential for disease. Wells are basically holes in the ground that are dug or drilled in different manners, protected against outside contamination where possible, and contain some mechanism, either a pump or in the case of artesian wells the pressure between two formations of rock, which forces the water to the top for use. There are three basic types of wells: dug wells, which are typically 10-30 feet deep and, therefore, are contaminated by surface water readily; driven wells, which are typically 30-50 feet deep and have a significant chance to become contaminated; and drilled wells, which are typically 100-400 feet deep and penetrate the bedrock and if properly sealed are least likely to become contaminated. Underground sources of water may also come to the surface through springs, which may or may not be contaminated depending on the source of the water. Artesian springs are typically safer than other types of springs.
Other means of collecting and using water include cisterns, which are big concrete boxes in the ground and water collected on the roof of a house which goes through some filters and then into the box for storage and use; infiltration galleries which are bottom drained sand filter trenches that are parallel to stream beds which filter the water as it passes through the filtering material so it becomes usable; and ponds or lakes.
There are numerous types of pumps which are used, based on the type of water well being installed, the depth to the water table, the type of soils encountered, and the quantity of water needed at the surface. All of them have the same function basically of moving the water from the aquifer to the surface so it can be utilized. Besides problems in the well which may lead to contamination, another problem historically for contamination has been the well pit. This has been eliminated by the use of a pitless well adapter that allows the water to go through the wall of the well casing or extension while protecting it from surface water or surface contamination. It is a connection between the underground horizontal discharge pipe and the vertical casing pipe or watertight casing. There are many different types of pitless well adapters that are usable depending on the circumstances.
To have a stable source of continuous water within a structure, there needs to be a pressure water storage tank to allow an adequate quantity of water to be available at all times when needed. About 10-30% of the volume of the tank contains water and the rest of the tank contains air to create the necessary pressure to move it through the system.
Water may be contaminated through naturally occurring sources of pollution. Natural sources of pollution include microorganisms such as bacteria, viruses, and parasites; radionuclides, such as radium and uranium found in rock or groundwater supplies; radon, a breakdown product of radium, which may be found in soil; nitrates and nitrites, found in water from the breakdown products of nitrogen compounds in the soil; heavy metals, such as arsenic, cadmium, chromium, lead, and selenium, which are found in rocks and soils; and fluoride which may be present in excessive amounts in soil and water.
Human activities can pollute the groundwater supply. Bacteria, viruses, and parasites may be found in human and animal waste. Overflowing septic tanks and waste from birds and farm animals create this problem. Concentrated animal feeding operations or factory farms put a large number of animals in a small area and therefore produce large amounts of waste material including nutrients and microorganisms, which when not handled properly can readily contaminate the water supply and the food supply. Heavy metals from mining and construction cause serious groundwater problems. Fertilizers and pesticides used on golf courses, lawns and gardens, and agricultural land pollute the groundwater as well as the surface water. Industrial products used in local businesses, factories, and industrial plants are common sources of hazardous chemicals in the water supply. Leaking underground tanks and pipes allow petroleum products, chemicals, and wastes to leak from corroded storage equipment and infiltrate the groundwater supply. Runoff and seepage from landfills and waste dumps contribute to the chemical wastewater infiltration problem. Household wastes including cleaning solvents, used motor oil, paints, and a variety of other chemicals are frequently mishandled or stored improperly and therefore can contaminate the groundwater. Lead and copper are found in drinking water pipes and therefore can contaminate the potable water used in the homes.
Another potential source of contamination of wells is the use of fracking in the exploration and production of domestic gas and oil. Fracking can lead to the contamination of groundwater because of spills, poor well construction, and the chemicals and materials used to separate the sources of energy from rocks under the ground. In several instances, fracking chemicals have been found in groundwater which has entered private drinking water supplies. The fracking process utilizes large amounts of surface and groundwater and therefore may endanger the amount of water available for human consumption. In some areas, there has been a concern about the potential for earthquakes where known geological faults exist.
As more wells are built in a given area, the cone of depression, which is like a small valley in the water, created by the pumping action underground extends the water table boundaries further out and therefore points of potential pollution which would have never entered this particular water table now do so, and create problems for all wells using this particular water table.
Once the water well has been put into operation, maintenance problems may occur because of: initial poor well design and construction; not developing the well system completely; borehole instability; a crust forming on the well screen from too much calcium, manganese, or iron in the water; biofouling due to iron bacteria forming a gelatin-like mass; corrosion of the metal well casing; over-pumping of the well which depletes the aquifer and also pulls sediment into the well; dissolved gases such as methane and hydrogen sulfide; and problems of the use of the aquifer since the aquifer does not recharge fast enough. (See endnote 8.)
Best Practices for Utilizing Private Drinking Water Sources (See endnotes 6, 7, 9)
- • Review the information above on General and Specific Sources of Contamination and Best Practices for Prevention, Mitigation, and Control and implement the Best Practices which relate to the potential problems found in a given locality.
- • Bored wells may be used providing the grouting or casing between the well and the soil goes down a minimum of 25 feet to impervious material. The casing should extend 12 inches above the ground and be at least 6 inches thick.
- • Drilled wells are the best for producing quality safe water. The drill bit goes down through the ground until the hole is completed and then it is withdrawn and in its place casing which does not allow outside contaminants to go into the well along with the screen at the end of it goes down into the ground. It is grouted to a least 25 feet below the surface or to a solid formation.
- • Use an experienced, licensed local well driller who knows the area. Determine if he is certified by the National Groundwater Association, has adequate equipment, and will submit well logs and furnish you a written contract which should cover compliance with local and state regulations; liability insurance; casing specifications to the bedrock; use of a sanitary well cap and grout seal; development of the well to its maximum yield of water; type of pump and use of a pitless well adapter; disinfection after drilling and installing pump; an estimate of well yield including well logs and pump test results; date of completion; and itemized cost estimate. The contractor must obtain a permit from the authorizing authority before starting any work on the well.
- • When building a new home or drilling a new well, understand the topography of the property, the direction of groundwater flow, the direction of surface water flow, and the potential pollution risks in the surrounding area as identified above under General and Specific Sources of Contamination and Best Practices for Prevention, Mitigation and Control.
- • All wells need to be uphill from immediate potential sources of contamination and have a minimum number of feet of separation from them. See endnote 6, page 5 for details for typical sources of contamination which may be in close proximity to the well including wetlands, storm drains, sewage disposal sites, lakes, barnyards, etc.
- • See endnote 6 for all required construction specifications and inspection requirements for a well as directed by the state of Pennsylvania (used as an example for all states and localities). These specifications include those for: casing; all materials and methods of use of these materials including grout; grout placement; drilling inspection; well casing and grouting inspection; pitless adapter and well seal inspection; well disinfection; and water quality analysis.
- • The design of the pump head must include all means of prevention of pollution of the water supply by lubricants, maintenance materials, dusts, grain, birds, flies, animals, etc.
- • Install a pressure tank with adequate storage for the water needs of the structure and in the event there is a low yielding well, increase the capacity of storage by adding an intermediate storage tank system. Set the pump pressure switch correctly so that when the water pressure falls below a certain level in the pressure tank, the pump will go on and recharge the pressure. (See endnote 10.)
- • Reduce peak water use of well water by purchasing washing machines, dishwashers, toilets, and faucets or showerheads which provide mechanisms for reducing the amount of water utilized during the operation of these units.
- • To correct reduced well yield because of pump or water system problems, have a licensed well water contractor or plumber determine if there is a leak in the system or worn pump parts and make necessary corrections.
- • To correct reduced well yield because of biofilm buildup, inspect the system by use of a camera and shock chlorinate the well and water system.
- • To correct reduced well yield because of mineral crust buildup, determine the problem by using a camera and have a licensed water well specialist treat the system.
- • To correct reduced well yield because of sediment plugging the screen or casing as determined by sediment found in the water, have a licensed well contractor redevelop the well.
- • To correct reduced well yield because of a collapse of the well casing or borehole usually due to age, depending on the cost, either recondition the entire well or plug it with concrete and construct a new well.
- • Always determine if new wells have been added to those in existence using the aquifer and have professionals determine if this is reducing well yield. If so this becomes a governmental problem, where the authorizing agency must make a determination as to the amount of water that may be withdrawn from the aquifer by each well and also whether or not to grant new well permits.
- • If sediment appears in a short period of time after the completion of the well, have the licensed well contractor repair all construction problems and if necessary construct a new well. Determine if this sediment will stop flowing into the well with continuous pumping over time. Establish a level of pumping which should be the maximum allowed in any given period of time. Make sure that the well seal has not been compromised.
- • If water quality changes, immediately test the water microbiologically and chemically to determine if there are problems in the well or in the water-bearing strata. Use a licensed well contractor to make all determinations and necessary corrections.
- • Carry out appropriate maintenance control procedures on a regular basis.
- • Obtain a permit before abandoning the well and follow all local and state specifications including an inspection by the authorizing authority. No surface water or other contaminants must ever be able to enter an abandoned well, which must never be able to be used for disposal of any kinds of substances including hazardous wastes.
- • Water taken from a pond or lake as its source must be fenced against livestock, free of weeds, algae and floating debris, must have an intake for the water 12-18 inches below the surface, go to a settling basin, through filtration, and finally be disinfected before use.
- • Spring water, unless it is artesian in nature, should be considered to be contaminated and therefore must be disinfected. However, since it may be difficult to determine if it is an artesian spring, always test the water supply microbiologically and chemically before using it.
- • Cistern water should go through a filtration process and be disinfected.
- • All water should be tested before starting to use it and then at least annually for wells, at the time of major potential contaminating events, and more frequently based on the source.
- • After a flood, boil all water for human consumption or other purposes before using. Remember that boiling will not be effective for chemical contamination.
- • After a flood, determine the conditions of the well, electrical system, and pump operation by professionals before using the well.
- • After a flood which may have contaminated the well, have the local or state health department take samples of the water, test the water both microbiologically and chemically, and if contaminated, have a licensed well contractor thoroughly disinfect the well and if necessary, the aquifer, before using as a potable water supply. Test again after the chlorine is gone before using the water. Wastewater from septic tank systems or chemicals seeping into the ground can contaminate the groundwater supply. In case of chemical pollution, experts in this area will need to make a determination on how to make the water safe and if necessary put in a new well to a different aquifer.
- • Emergency disinfection of water includes: straining the water through cheesecloth and then boiling for 10 minutes followed by cooling and transferring from one clean container to another to re-aerate it; or using household bleach which contains 5.25% available chlorine at a rate of two drops per quart of clear water after straining, shaking thoroughly, allowing to stand for 30 minutes, and pouring off the clear liquid from the top while not allowing residue to enter the new container. This can also be accomplished by using chlorine tablets or iodine.