Municipal water supplies are regulated under the Safe Drinking Water Act, which mandates routine testing and treatment. Maintenance and testing of private water supplies (wells, springs and cisterns) is the responsibility of the owner. Virginia Cooperative Extension offers water testing and education for private water supply users across the state
Drinking water clinics are held in county Extension offices each year. Here's how it works:
Participation is voluntary and open to anyone with a well, spring or cistern. Participants pick up a sample kit and receive instructions about how to collect the samples from their household tap and where and when to drop off their samples.
Following directions carefully, participants collect their samples and complete a short questionnaire. Samples are dropped off locally, so shipping is unnecessary. We coordinate getting the samples to Virginia Tech's campus for analysis.
Samples are analyzed for total coliform and E. coli bacteria, nitrate, lead, copper, arsenic, fluoride, sodium, hardness, iron, manganese, total dissolved solids, pH, and sulfate. The cost for one sample kit in 2015 was $49. Confidential results are prepared and returned to the Extension office.
Results are returned to participants and explained at a local interpretation meeting. Information is provided about addressing water quality problems, routine care, and maintenance of private water supplies.
Water systems in Clarke County (2011 - 2015)
106 samples analyzed
Serving 243 people
Well depth: 40 to 700 feet
Well age: 4-115 years
67% of participants
installed. The most
were most commonly
reported. Eight percent
did not know what
type of well they
Contaminants in water may be health-related (e.g., bacteria) or a nuisance (e.g., hardness causing scale) and can come from a variety of sources.
Some contaminants originate from geology, the sediment or rock where the water is stored. Others are a result of land usage or activities on the earth's surface, such as lawn fertilizer, animal waste, or chemical spills.
Proper construction of a well can protect household water quality by preventing surface water, which may carry many contaminants, from entering the groundwater supply. Wells should be constructed with proper casing, grout seal, and a sealed well cap. Contamination sources, such as livestock and septic systems should be at least 50 feet away from the well head.
Treatment devices and plumbing components can also influence water quality by adding contaminants or changing water chemistry.
Landuse and nearby activities
and water treatment
Well construction and location
Where do contaminants come from?
The most common contaminants found in household water in Clarke County were total coliform bacteria, sodium, hardness, total dissolved solids (TDS) and E. coli bacteria.
Total coliform bacteria presence is an indication that surface water may be entering a well and other more harmful microorganisms may be present. E. coli were found in 21% of Clarke county samples and are a sign that human or animal waste is entering the water supply.
Hardness is composed of calcium and magnesium, which originates in bedrock such as limestone. Sodium is associated with water softeners, which are commonly used to remove hardness. Sodium can have negative health effects in excess levels.
Total dissolved solids, or TDS, is a measure of all dissolved impurities in water, and can be made up of sodium, nitrate, or other dissolved contaminants. It is a nuisance contaminant.
Household water quality in Clarke County: Common Contaminants
Click the water drops for more information about each contaminant. For information about other common contaminants, please visit our Resources Page.