Thursday, November 1, 2012

Is the Water Well Safe? Is the Water Well Good?

When I alerted all of the homeowners of my little neighborhood of the Prince William County Virginia Cooperative Extension (VCE) Office drinking water clinic for testing well water next week, one of my neighbors told me “I don’t have to test my water until I sell the house.” I was absolutely silenced by that comment. How do you respond to that?  In fact my neighbor does not ever have to test her water in Virginia. It is only that many mortgage companies require a basic test of water potability to close a mortgage. This most basic test of potability consists of a bacterial test and is written into most purchase contracts. My neighbor has lived in their house for 8 years with no intention of moving, so in essence she told me that she does not intend to ever test her drinking water. Because she does not “have to,” my neighbor has no intention of monitoring the most basic health risk- contaminated water. In fact a malfunctioning well (either due to contamination or component failure) can be expensive to repair or replace, but the harm from contamination is only likely to impact your family’s health and Virginia lets you do as you want. As long as the well continues to pump water you can ignore it.

The most basic water test usually performed at purchase or commissioning of a well is for total coliform bacteria. Total coliform bacteria is always present in manure and sewage, but is also present in soil and vegetation and surface water and while it may indicate that the well has been impacted by a nearby septic system or manure composting, it can also mean that surface water is getting into the well either directly through a failing casing or grouting or improper construction or well cap or by other means (karst terrain). In a world not subject to chemical contamination of the aquifer (from pesticides, herbicides, solvents and fuels present in stormwater runoff) or high natural concentrations of arsenic or metals, a coliform bacteria test is a fairly decent test to determine potential outside impact to a well and sound construction. Well water that test positive for coliform is often tested for E. coli (Escherichia coli) or fecal coliform types of coliform bacteria. E. coli or fecal coliform bacteria are present only in the digestive systems of humans and animals and a positive test result indicates contamination by animal manure or sewage. If a well tests positive for E. coli or fecal coliform the water is unsafe to drink (it is “poopie” water). Such wastes may include one or more of a variety of potentially pathogenic microorganisms such as Salmonella, Shigella, enteric viruses, Giardia or Cryptosporidium that may be present in human or animal manure and can cause severe illness. People have died from drinking water contaminated with cryptosporidium.

In Virginia and most other states, regulations for private well construction and testing apply only to newly constructed wells. In addition to various construction requirements (which include setback distance requirements from certain potential pollution sources such as septic tanks and leach fields), newly-constructed wells must be tested for the presence or absence of coliform bacteria. Although some municipalities and counties in other states have private well testing programs, only New Jersey has a statewide private well testing program which requires regular testing of private well water and treatment of the water if any of the standards are exceeded. Everywhere else in the country you are on your own to ensure that you are drinking safe and clean water.

The issue of whether water is safe to drink is separate from whether the water is free of unpleasant contaminants like iron, manganese, chloride, and low levels of sulfur or if the well can deliver adequate amounts of water.  Groundwater can change over time, become contaminated or dry up from inadequate recharge or overuse and wells do not last forever.  There are three aspects to a private well- the well and well system, the water quality and the water quantity. Failure of any of these can impact your life and the value of your home. The well is essentially a hole in the ground. Shallow wells (those less than 50 foot deep) are generally dug or bored into the ground and have larger diameters (2-4 foot). Shallow wells are more prone to contamination and drought and bored wells have the shortest life. Deeper wells are called drilled wells because they are drilled into the ground to depths from 50-450 feet or more and because of the need for drilling rigs cost much more to build. The diameter of a drilled well is 6-8 inches.

Generally, drilled wells provide a safer source of drinking water, and are less often impacted by drought. In igneous and metamorphic rock systems like the Piedmont of Virginia, the fractures and fault lines formed in the rocks store and transmit groundwater. The size and number of water bearing fractures varies and there is a wide variation in well yields from under 1 gallon per minute to over 50 gallons a minute depending on location and specific site geology. Fractures can become fouled with mineral deposits or iron bacteria or simply go dry over time. The specific geology and water quality will determine the life span of a well. Aquifers can go dry unexpectedly, but all wells will fail over time. The lifespan of a drilled well is assumed to be 20-50 years, but varies tremendously based on site specific conditions. I personally know of a drilled well that lasted almost 65 years before the well stopped producing water, but if you are buying a home with a well over 20 years old you will need to budget for drilling a new well. Make sure that is considered in the price you pay and that the property has another location to drill a well.  

The well system consists of the well, the well casing, the inlet for water, and the pumping system. The casing is the structure around the well hole to prevent its collapsing. It could be a steel or plastic casing or an open hole in the bedrock. In this part of Virginia, the Piedmont, the top of the well is lined with steel for 50 feet and then the well is open in the bedrock allowing the water to flow into the well. The well casing will rust over time. The well casing should be 1-2 feet above the land surface to make sure that during storms and flooding that nothing washes down the well. There should be no holes or cracks in the visible portion of the casing and the well cap should be tightly bolted closed.

The pumping system includes the pump, piping and electrical connections to pump water from the well into the house and a pressure tank to maintain constant water pressure in the house. Shallow wells usually use centrifugal pumps and are often located in a pump house or the basement. Drilled wells have submersible pumps. The pump and pumping systems are the most likely components to fail in a well. The average life of a submersible pump is variously reported as 12-15 years, but many pumps fail in the first few years. The essential components of a modern drilled well system are: a submersible pump, a check valve (and additional valve every 100 feet), a pitless adaptor, a well cap, electrical wiring including a control box, pressure switch, and interior water delivery system. There are additional fittings and cut-off switches for system protection, but the above are the basics and each and every component must work properly for your well to function properly.

In addition, in order for a well to keep supplying water to your home the components within the basement must all continue to work. These components provide constant water pressure at the fixtures in the house and the electrical switch that turns on the pump. The pump moves water to the basement water pressure tank, inside the tank is an air bladder that becomes compressed as water is pumped into the tank. The pressure in the tank moves the water through the house pipes so that the pump does not have to run every time you open a faucet. Bladders and electrical switches will fail over time and valves and switches and impellers on the pump can break, foul or find any number of ways to fail. You have to assume that pump systems that are older than 12 years are on borrowed time. It does not mean that a pump system cannot last 25 years or more, but I would not bet on it. Also, if your pump fails consider replacing other components of the system at the same time.

If buying a home with a well you need to consider the construction, condition, age and location of the well in addition to water quality and quantity. Make sure that the well is uphill (up gradient) and at least 50 feet (preferably 100 feet) from potential pollution sources like septic tanks, septic drain fields, stormwater drainage ditches and sources of contaminated runoff. Clay loams or silty clay soils filter pollutants and protect an aquifer. If there is not a lot of top soil and overburden or the soils are sandy, make sure that the well is deep and test the well for chemical contaminants before purchase. A shallow water table and fractured bedrock may provide larger quantities of water, but the shallow fractured rock systems are easily contaminated.

When testing your water you need to consider nearby likely sources of contamination and test for those contaminants, but the contaminants that occur in nature and from human and animal waste that can impact health need to be tested for:  E. coli or fecal coliform and total coliform, nitrate, sodium, sulphate, lead, floride and copper. In addition, water taste and aesthetics are impacted by hardness (calcium carbonate), chloride, iron, manganese and pH and you should test your water for these before you buy a home or purchase a treatment system. 

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