Well Water Testing

Individuals on private wells who would like to have their water tested can use the Frederick County Health Department (FCHD) or a state-certified private water lab for sample collection. 

Appointments and Processing Times: The FCHD schedules samples Monday through Thursday and generally has a longer turnaround time (normally 2-3 weeks) for receiving results compared to the private labs.

Types of Testing: The FCHD collects samples from private wells located in Frederick County and can test for coliform bacteria, nitrate, and/or turbidity. For additional types of testing, such as PFAS, lead and copper, or testing that requires a quick turnaround time, please contact one of the private labs.   

Drop-off Samples: Please note that while the FCHD does not accept drop-off water samples from the public, private labs may accept drop-off samples and should be contacted to confirm drop off process and availability. Drop-off samples, which are normally collected by the resident and processed by the lab, can help save on the cost of water testing.

Please select one of the following links to proceed:

FCHD Application for Private Water Well Testing

State Certified Private Drinking Water Labs in/near Frederick County

Entire list of State Certified Private Drinking Water Labs 

More Information:  Please visit Private Drinking Water Wells | US EPA

For printable well disinfection directions click here

The Maryland Department of the Environment procedures for disinfection of the well and water distribution system is as follows:

Disinfecting Your Drilled Well

There are a number of reasons why bacteria may be present in your well water.  Disinfecting the water system will kill bacteria that have entered the system due to new well construction, installation or replacement of the well pump, or plumbing repairs.

Chlorinating the well will not provide a permanent solution to an ongoing contamination problem. This process only destroys existing bacteria. If bacteria are detected after chlorination, that is evidence that contamination continues to enter the system, and that some problem exists with the ground water, well, storage, or plumbing. If bacterial contamination persists after repeated disinfection of the well, repair or replacement of the well may be required.  To properly disinfect your well, follow these steps:

1. Notify all users not to consume water.
2. The chart on the back of these instructions indicates the proper amount of chlorine to add to the well.
3. Mix the liquid chlorine in a container with 5 to 10 gallons of water.
4. Remove the well cap and pour the chlorine-water mixture into the well.  If the well has an old style cap, pour the solution through the vent in the sanitary seal (you may need to remove a plug or bolt to access the opening).  If using solid forms of chlorine, add directly to the well.
5. Attach a garden hose to an outside hose bib, and run water into the well for 1 to 2 hours.  This will re-circulate water into the well and ensure mixing of the chlorine and water.
6. Wash the interior of the well, the cap, and the pump apparatus thoroughly with the chlorinated water.  Remove the hose and replace the cap.
7. Turn off the circuit breaker to the electric hot water heater, or turn the gas control on a gas water heater to “pilot”.
8. Run all inside and outside taps, one at a time.  Include both hot and cold taps, barn taps, showers, and taps at the bottom of the hot water heater and the pressure tank.  Flush each toilet and run each washing machine and dishwasher until bleach is smelled at the fixture.  Turn the water off at each tap or fixture once there is a smell of chlorine.
9. Let sit for a minimum of 12 hours, preferably 24 hours.  Do not use the water during this time.
10. Flush the well water from an outside faucet into a “safe” area, such as the lawn or an open field.  Do not put the chlorine solution into a septic system, because it may damage the system.  Do not flush the chlorine solution into a creek or other water body where it could kill fish or other wildlife.  Do not flush into a flower or vegetable garden because the solution could kill plants.  It is best to flush the system intermittently, running the water for no longer than one hour at a time.  Flush the hot water tank using a hose to the sump pump or outside.
11. Finish flushing the remainder of the system by running each faucet and fixture until no chlorine odor is detected.  The small amount of chlorine left in the building’s plumbing system can safely be put down the drain.
12. Check for chlorine before re-sampling the water.  If any chlorine residual remains, the bacteriological analysis will not be valid.

Quantities of Disinfectant Required for Water Well Disinfection

(COMAR 26.04.04N (5))

Chlorine is available in both liquid (household or commercial bleach) or solid (available where pool supplies are found) forms.  Liquid bleach tends to “float” in a well, granular solid chlorine may dissolve before reaching the bottom of the well, and chlorine tablets may sit on the bottom of the well and slowly dissolve, making it difficult to flush the chlorine out of the system.  The most effective chlorination technique uses both liquid and solid forms.  Use half of the quantity of solid chlorine shown plus half of the liquid volume shown for the depth of your well.

T = tablespoons, oz = ounces (by weight), C = cups, Q = quarts,

Rows A are amounts of calcium hypochlorite (Solid Chlorine, Granular or Tablets) (70%)

Rows B are amounts of liquid household bleach (5.25%)

Maryland Department of the Environment, Water Supply Program

1800 Washington Blvd, STE 450 · Baltimore MD 21230-1708

(410) 537-3729, (800) 633-6101 (in Maryland)

www.mde.state.md.us

The Certificate of Potability (COP) is issued by the Frederick County Health Department (FCHD) and is needed for an Occupancy Permit for new homes with wells in Frederick County.  Minimally it includes bacteria, nitrate, and turbidity testing along with well construction information.  The water samples must be taken by a certified water sampler and processed at a Maryland-certified lab.  

Local certified labs 

If a private lab is used to collect samples, the lab must submit results to the FCHD.  It will take approximately one week to process the paperwork once it is received from the private lab.

COP samples can also be taken by the FCHD.  The turnaround time will generally be longer than when a private lab takes the samples.   

Water samples needed for a COP:

• Two bacteria samples (collected at least 24 hours apart)
• Both collected bacteria samples must be absent of total coliforms and E.coli
• One nitrate sample not above 10 mg/L 
• One turbidity sample less than 10 NTU 

Call the FCHD at 301-600-1717 with questions about samples that do not meet these standards.

Individuals on private wells requiring water testing for in-home daycares, foster care or adoption can use either the Frederick County Health Department (FCHD) or a state-certified private water lab for sample collection. 

In addition, new daycares will need a review of their septic capacity to ensure that the additional individuals can be accommodated.  Please call 301-600-1717 to start this review.

Appointments and Processing Times: The FCHD schedules samples Monday through Thursday and generally has a longer turnaround time (normally 2-3 weeks) for receiving results compared to the private labs.

Private Laboratories: 

• Samples must be collected by a certified sampler, so drop-off samples that are taken by the resident and processed by the lab will not be accepted. 
• Private water samples taken by a certified sampler from a state-certified lab within the last six months may be accepted in lieu of additional testing.  For more information, please contact our office at 301-600-1717.

Please select one of the following links to proceed:

FCHD Application for Private Water Well Testing

State Certified Private Drinking Water Labs in/near Frederick County

Entire list of State Certified Private Drinking Water Labs

More Information: For more information about private water wells, please visit 

Private Drinking Water Wells | US EPA

A TNC is a Transient Non-Community Water System according to The Environmental Protection Agency (EPA). (See https://www.epa.gov/dwreginfo/information-about-public-water-systems.) 

TNCs serve at least 25 people or more per day for at least 60 days of the year, but not necessarily the same people or on a regular basis. The population is considered transient because they are only there for a short period of time. Examples of TNCs include restaurants, gas stations, churches, wineries, and many other public places that have their own well. Oversight of TNCs is delegated to the Frederick County Health Department by the Maryland Department of the Environment (MDE).  There are approximately 150 TNCs in Frederick County.  Information about Frederick County TNCs and the many other places regulated by the EPA is available at https://echo.epa.gov/.

For questions about TNCs, contact the Community Services office at 301-600-1717 or CommunityServicesOffice@FrederickCountyMD.gov.