Maryland county well guide

Well Water in Montgomery County, MD: Testing, Contractors and Rules

About 29,960 households in Montgomery County, 7% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
7%of households on a private well
Share on wells, county vs state
Montgomery County7%
Maryland average26%
6licensed contractors serve the county
18 mito the nearest certified lab, EMSL Analytical, Inc – Beltsville
Nostatewide test required when a home is sold

About 29,960 homes in Montgomery County are on a private well. That is 7% of households, enough that every township has well owners and few of them have had the water tested recently.

Local rules for wells in Montgomery County

The rules that apply in Montgomery County are set at the state level in Maryland. New wells must be tested before use, and nothing is required at sale. Some counties and townships add permits or setbacks of their own, so check locally before drilling. The state's own recommendations are below.

At a glance

Water test for a new wellRequired

Yes. A well construction permit from the county health department is required before drilling, the well must be built by a Maryland licensed well driller to COMAR 26.04.04 (grouted casing, 50 ft from a septic tank, 100 ft from a drainfield, minimum yields by use), and before the house can be occupied the county issues a certificate of potability based on a sample from an MDE-certified lab that passes for total coliform bacteria, nitrate and turbidity. Several counties add tests (Anne Arundel, Calvert and other Coastal Plain counties add arsenic and radium; Piedmont counties often add pH and radon screening). The driller files the well completion report with the county.

Water test when a home is soldNot required statewide

No statewide requirement. Maryland's residential disclosure asks about the water supply and known problems, and a few counties require a bacteria test or a yield test when a property on a well changes hands (check the county health department). FHA, VA and USDA loans normally require a bacteria, nitrate and lead sample from a certified lab before closing.

What the state recommends

University of Maryland Extension and MDE recommend testing a private well every year for coliform bacteria and nitrate, and every three to five years for pH, hardness, iron, manganese, lead, copper and total dissolved solids. Add arsenic and radium in the Coastal Plain (the Aquia and Patuxent aquifers under Anne Arundel, Calvert, Prince George's and the Eastern Shore), radon and uranium in the Piedmont, PFAS near Patuxent River, Fort Meade and other airfields, chloride and sodium on the lower Eastern Shore, and test again after flooding, well work or a change in taste, color or smell.

Free or low-cost testingAvailable

No free program. The county health departments do not run labs but will tell you which certified labs serve the county, and several commercial labs on the MDE list (Water Testing Labs of MD, Home Land Labs, Fredericktowne Labs, Certified Water Testing, Chesapeake Environmental) are built around homeowner samples and run the potability panel for $60 to $150. University of Maryland Extension's Wells and Septic Systems program runs periodic free screening clinics.

Getting your water tested near Montgomery County

The nearest certified lab is EMSL Analytical, Inc – Beltsville in Beltsville, about 18 miles from the county center. There are 17 more within 40 miles, listed below with what each tests for.

14 certified labs within 40 miles

Licensed well contractors serving Montgomery County

Licensed help in Montgomery County includes Earth Data Incorporated and Geo-Technology Associates, Inc and 4 others. Every listing was matched to the Maryland license list; the "verify" link on each profile opens the state lookup.

Well depth and water chemistry

Well depth and water chemistry in Montgomery County follow the rock underneath it. Typical wells here run 100 to 400 ft in the fractured crystalline rock of the Piedmont (Montgomery, Howard, Baltimore, Carroll and eastern Frederick counties), where yields are modest and a dry hole is possible; 50 to 300 ft in the sand aquifers of the Coastal Plain on the Eastern Shore, deeper (300 to 800 ft) in Southern Maryland where wells reach past the shallow arsenic and radium zones into the Magothy and Patapsco; 100 to 300 ft in the limestone and sandstone of the Hagerstown Valley and the western mountains. Contaminants worth testing for in this part of Maryland include coliform bacteria (statewide, worst in shallow and older wells), nitrate (eastern shore farm and poultry country, shallow columbia aquifer wells).

Typical well depth

Varies by location. Check the state well record search for logs of nearby wells.

Contaminants to test for
  • Coliform bacteria (statewide
  • Worst in shallow and older wells)
  • Nitrate (Eastern Shore farm and poultry country
  • Shallow Columbia aquifer wells)
  • Arsenic (Aquia aquifer in Anne Arundel
  • Calvert
  • Prince George's and the upper Eastern Shore)
  • Radium (Patuxent and Patapsco aquifers of Anne Arundel and Southern Maryland)
  • Radon and uranium (Piedmont granite and gneiss)
  • Acidic corrosive water that pulls lead and copper from plumbing (Piedmont and Coastal Plain)
  • Iron and manganese (Coastal Plain sands)
  • Hardness (Hagerstown Valley limestone)
  • Saltwater and sodium (lower Eastern Shore and Bay-front wells)
  • PFAS near military airfields and industrial sites

Neighboring counties: Howard County, Prince George's County, Anne Arundel County, Frederick County.

What well work costs in Montgomery County

Bacteria test (coliform and E. coli)$41published Maryland lab fees
Nitrate test$18published Maryland lab fees
Broad panel (metals and minerals)$85 to $450state and university lab packages
Well inspection$250 to $550$350 to $900 with water testing
Submersible pump replacement$1,000 to $2,500installed; deep wells cost more
Pressure tank replacement$800 to $1,500installed
One treatment unit$700 to $3,500softener, iron filter or UV, installed
Multi-stage whole-house treatment$2,500 to $10,000+several units or whole-house RO, installed
New well, complete$6,000 to $16,000typical 200 ft well with pump; drilling alone about $20 to $30 per foot; deeper wells cost more
Shock chlorination$80 to $200by a contractor; under $30 to do yourself

Maryland state lab fees; a county health department may add a collection fee ($50 in Frederick County). Installed costs are national 2026 ranges; local quotes vary with depth, access and materials. Sources, checked September 2026: Maryland Department of Health lab fees, Frederick County Health Department, HomeGuide cost guides, Angi: cost to shock a well.

Questions Montgomery County well owners ask

How many homes in Montgomery County are on a well?

About 29,960, or 7% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to Montgomery County?

EMSL Analytical, Inc – Beltsville in Beltsville, about 18 miles away. Call first to ask whether they accept homeowner samples.

Do I need a permit to drill a well in Montgomery County?

Yes. A well construction permit from the county health department is required before drilling, the well must be built by a Maryland licensed well driller to COMAR 26.04.04 (grouted casing, 50 ft from a septic tank, 100 ft from a drainfield, minimum yields by use), and before the house can be occupied the county issues a certificate of potability based on a sample from an MDE-certified lab that passes for total coliform bacteria, nitrate and turbidity. Several counties add tests (Anne Arundel, Calvert and other Coastal Plain counties add arsenic and radium; Piedmont counties often add pH and radon screening). The driller files the well completion report with the county.

What does a well test cost near Montgomery County?

Published lab fees in Maryland: $41 for a bacteria test and $18 for nitrate. Maryland state lab fees; a county health department may add a collection fee ($50 in Frederick County). Mail-in kits cost about the same as walking in.