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 $50. 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.
70% of participants
The most common
sediment filters and
Water systems in Loudoun County (2009 - 2015)
262 samples analyzed
Serving 760 people
Well depth: 35 to 900 feet
Well age: 1 to 140 years
Drilled wells were
did not know what
type of system they
had. 15,000 Loudoun residents use wells!
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 Loudoun County were sodium, coliform bacteria, low (<6.5) pH, manganese and lead.
Total coliform bacteria presence is an indication that surface water may be entering a well and other more harmful microorganisms may be present. Total coliform were present in 27% of Loudoun samples. E. coli were found in 6% of Loudoun samples and are a sign that human or animal waste is entering the water supply.
Sodium above 20 mg/L was found in 29% of samples, most likely from water softening devices. Manganese is a nuisance contaminant originating from geology, and was found in 13% of Loudoun samples.
Low pH (<6.5) occurs naturally in some Virginia geology. Although not a concern in itself, low pH can be a driver of how corrosive the water is. Once water enters the house, can result in metals such as copper and lead leaching into the water from plumbing components Lead was found in first draw samples exceeding 0.015 mg/L in 12 % of samples.
Household water quality in Loudoun County: Common Contaminants
Click the water drops for more information about each contaminant. For information about other common contaminants, please visit our Resources Page.