Groundwater in Montgomery County

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There are approximately 50,000 water wells in Montgomery County, the majority of which serve individual homes. The remainder are heat pump, monitoring, and irrigation wells, or serve commercial facilities. Only those wells that are for community (such as the Town of Poolesville) or noncommunity supplies (such as a restaurant served by a well) are regulated on a continuous basis and require frequent and regular sampling. No regulations or standards exist for the ongoing sampling of residential individual water wells, except for facilities licensed for some other reason, e.g. child care or group home.

Private wells are sampled initially for a Certificate of Potability (COP) according to Code of Maryland Regulations. Usually wells are not sampled again until the property is sold and a sample is required for loan approval, or if homeowners take the initiative and have the well sampled for their own information.

The Montgomery County Department of Environmental Protection encourages you to understand the quality of your well water supply. It is important to know that over time, the conditions in your well can change naturally or from human activity which can influence the quality and safety of the water in your well.

Why Is a Checkup Important?

A properly constructed and maintained household-supply well will provide you with many years of quality service. The National Ground Water Association recommends routine annual maintenance checks to ensure the proper operation of the well and prolong its years of service, as well as monitor the water quality.

What Does a Checkup Involve?:

a flow test to determine the system output,
a check of pump motor performance,
pressure tank and pressure switch contact, and
water quality

The water quality testing should sample at a minimum for bacteria and nitrates as well as any other specific analytes of concern based on local conditions.

How Do I Arrange for a Checkup?

Contact a local water well contractor and ask if he or she conducts the type of maintenance check described. You can locate NGWA-member contractors in your area by calling NGWA at 800/551-7379. You can also check your phone book under "Well Drilling and Service." Check with other well owners or other knowledgeable people for good contractor referrals, and ask the contractor for a list of references. Some additional considerations when choosing a contractor are certification and licensing.

What Are Other Steps I Can Take to Protect My Well?

Keep hazardous chemicals, such as paint, fertilizer, pesticides, and motor oil far away from your well, and maintain a "clean" zone of at least 50 feet (15.24 meters) between your well and any kennels or livestock operations. Also, always maintain proper separation between your well and buildings, waste systems, or chemical storage areas. Your professional water well contractor is familiar with the applicable local codes.

Periodically check the well cover or well cap on top of the casing (well) to ensure it is in good repair and securely attached. Its seal should keep out insects and rodents.
Keep your well records in a safe place. These include the construction report, and annual water well system maintenance and water testing results.
Get your water tested anytime there is a change in taste, odor or appearance, or anytime the system is serviced.

Well construction, depth, and age are the most important factors when considering if the well water supply is sufficiently protected from bacteriological sources. Wells located down in a pit or buried in the yard were generally not constructed with cement grouting and are of sufficient age that plumbing materials in the well may be deteriorating. Pit wells often collect stormwater, allowing it to flow down the top of the well. Buried seal wells have rubber gaskets that deteriorate and allow contamination to enter. A properly constructed well will have cement or other approved grouting to prevent surface water from entering the well and a pitless adapter that provides a sanitary seal between the soil and the well water. Deep wells (40- 200 ft.), usually with metal casing greater than 40 feet are less susceptible to contamination than shallower wells (13-40 ft.).