How to Test Your Well Water in Maryland
How to Test Your Well Water in Maryland
If your home is on a private well, you are responsible for the safety of your own water supply. Here's exactly what to test for, when to test, and how to interpret the results.
Why Well Water Testing Matters
Unlike municipal water, private well water is not tested or treated by any government agency. You are entirely responsible for monitoring your own water quality. Maryland has approximately 450,000 private wells — and many homeowners have never tested their water, or haven't tested it in years.
The consequences of untested well water range from cosmetic (orange staining from iron) to serious health risks (bacteria, nitrates, arsenic). Many contaminants have no taste, odor, or color — the only way to know they're present is to test.
Maryland law requires well water testing at the time of a home sale, but annual testing is strongly recommended for all private well owners.
What to Test For: The Maryland Well Water Panel
The right tests depend on your location, well depth, and any symptoms you've noticed. Here's a tiered approach:
Annual Minimum
- Total coliform bacteria
- E. coli (fecal coliform)
- Nitrates/nitrites
These are the most common health-risk contaminants in Maryland wells. Bacteria can enter any time — a cracked well cap, flooding, or nearby septic issues. Nitrates are a serious risk for infants.
Every 3–5 Years (Comprehensive)
- pH (acidity)
- Iron and manganese
- Hardness (calcium/magnesium)
- Arsenic
- Lead
- Volatile organic compounds (VOCs)
- Total dissolved solids (TDS)
These contaminants change slowly over time. pH, iron, and hardness are the most common issues in Calvert and Anne Arundel County well water. Arsenic and lead are health risks that have no taste or odor.
As-Needed (Symptom-Driven)
- Hydrogen sulfide (rotten egg smell)
- Iron bacteria (orange slime in toilet tank)
- Radon
- Pesticides/herbicides (near agricultural land)
- Sodium (near roads with salt application)
Test for these when you notice specific symptoms or have reason to suspect contamination from nearby land use.
When to Test Your Well Water
How to Collect a Water Sample
Proper sample collection is critical — a contaminated sample bottle or improper collection technique will produce inaccurate results. Follow these steps:
- 1Use the sterile sample bottles provided by the laboratory — do not substitute other containers.
- 2Collect from a cold water tap that is directly connected to the well supply — not a filtered tap, not a tap with an aerator if possible.
- 3Run the water for 2–3 minutes before collecting to flush the supply line.
- 4Do not touch the inside of the bottle or the cap.
- 5Fill the bottle to the fill line — do not overfill.
- 6Refrigerate the sample immediately and deliver to the lab within 24 hours (bacteria samples) or 48 hours (chemistry samples).
- 7Note the collection date, time, and tap location on the sample label.
Understanding Your Results: Maryland Context
pH below 7.0
Acidic water — corrodes copper pipes, causes blue-green staining, pinhole leaks. Very common in Anne Arundel County (Aquia aquifer). Fix: calcite acid neutralizer.
Iron above 0.3 ppm
Orange staining on fixtures, laundry, and appliances. Common throughout Calvert County. Fix: dedicated iron filter (not a softener alone above 3 ppm).
Hardness above 7 GPG
Scale buildup in water heater, pipes, and appliances. Shortens appliance life. Fix: water softener.
Coliform bacteria present
Indicates contamination pathway — cracked well cap, surface water infiltration, or nearby septic issue. Fix: shock chlorination + UV system + fix the entry point.
Nitrates above 5 mg/L
Elevated risk, especially for infants. Above 10 mg/L is the EPA action level. Fix: reverse osmosis for drinking water, or whole-home nitrate removal.
Hydrogen sulfide present
Rotten egg smell. Can come from the well, the water heater anode rod, or sulfur bacteria. Fix depends on source — see our sulfur smell guide.
Frequently Asked Questions
How often should I test my well water in Maryland?
Maryland recommends testing annually for bacteria and nitrates. A comprehensive panel including pH, iron, hardness, and other contaminants should be done every 3–5 years, or any time you notice a change in water taste, odor, or appearance.
Where can I get my well water tested in Maryland?
Maryland Department of the Environment (MDE) maintains a list of certified water testing laboratories. Many county health departments also offer testing. Deep Dive Plumbing Maryland tests water on-site as part of every well system evaluation.
What should I test my well water for in Maryland?
At minimum: total coliform bacteria, E. coli, nitrates, and pH. A comprehensive panel should also include iron, hardness, manganese, arsenic, and lead. If you smell sulfur, add hydrogen sulfide. If you have orange staining, add iron bacteria.