Well water testing in Montgomery County: what to test and how

The yearly minimum

Texas A&M AgriLife's Water Well Basics publication says that at minimum a well should be tested every year for nitrate, total dissolved solids (TDS), and E. coli or fecal coliform bacteria. Bacteria are the test that matters most for safety. TDS tells you how much dissolved mineral is in the water, and nitrate is a standard drinking-water check.

The same publication lists reasons to test again sooner: you suspect contamination, the color, taste or smell changes, the pump or well has been serviced, or someone who drinks the water has a suspicious illness. Service work can disturb a well, so a pump or tank job is a reasonable moment for a fresh bacteria sample.

What local geology adds to the list

Under Montgomery County the water comes from sand layers of the Gulf Coast aquifer system. A 1971 Texas Water Development Board report, the most detailed county study we could open, describes Chicot aquifer water as very fresh, often acidic and iron-rich, and Evangeline and upper Jasper water as fresh and often hard. Dissolved solids in most Evangeline samples ran between 250 and 400 milligrams per liter. That report is more than fifty years old, so treat it as background and let your own test decide.

The state's own summary of the Gulf Coast aquifer says water quality is generally good in the central and northeastern parts, with dissolved solids under 500 milligrams per liter. In practice that means many owners ask about three extras beyond the yearly minimum: iron, hardness and pH. Iron staining, a metallic taste and slime in a toilet tank are common prompts.

How to collect a bacteria sample

Lesikar's Texas AgriLife sampling sheet for bacteria is short and strict, and each step exists for a reason. A clean-looking sample from the wrong tap can fail for no good reason.

• Use a sterile bottle from a lab or your local extension office.
• Pick a cold-water tap. Take off the aerator. Do not use a hot tap, a mixing faucet, a leaky tap, a filtered or softened tap, or a hose.
• Sterilize the tap by flaming it with a lighter, wash your hands, then run the water at full flow for five minutes.
• Reduce the flow to a pencil stream. Open the bottle without touching the inside of the cap or bottle, and fill it to the top.
• Close it at once, refrigerate it, and get it to the lab quickly. Six hours is best, up to 30 hours is accepted, and many labs do not take bacteria samples on Fridays.

Where to take it

Montgomery County Environmental Health Services in Conroe publishes a short list of labs that test private well water, with addresses in Houston, Conroe, The Woodlands and Coldspring. Call 936-539-7839 for the current list. Texas AgriLife also says a lab accredited under the National Environmental Laboratory Accreditation Program is the safe choice if you are picking one on your own.

The Lesikar sheet puts a bacteria test at 8 to 25 dollars, but that sheet dates from 2022 and prices have moved. Bob Vila's well guide gives 30 to 150 dollars for a do-it-yourself kit and 100 to 500 dollars for a professional test covering more than bacteria. Treat every price as a range and ask the lab.

Reading a result

A positive bacteria result does not always mean the well is bad. It can mean a dirty tap, an unsealed wellhead, flooding around the casing, or a leak in the plumbing. Ask the lab how they report results and ask a provider to inspect the wellhead cap, the casing seal and the area around the pitless adapter. The Conroe area page covers wellhead height and flooding.

Iron bacteria show up as reddish-brown slime in a toilet tank or wherever water stands for several days, and the Lesikar sheet says you do not need a lab test to identify it. If you see it, tell the provider; it can clog screens and fittings. The well owner FAQ answers other common questions about odor and staining.

Common questions