Testing your Texas well water: what to test for and when
Private wells are the owner's responsibility. What Texas A&M AgriLife and TCEQ recommend testing, how to collect a sample and how to read the result.
If your home is on a private well, nobody tests the water for you. Public water systems in Texas are regulated by the Texas Commission on Environmental Quality (TCEQ), which requires them to test and report; a private household well is regulated only in how it is drilled, not in what comes out of it. Quality is the owner's job.
How often to test
TCEQ and the Texas A&M AgriLife Extension Service's Texas Well Owner Network recommend that private well owners test at least once a year for bacteria and nitrate. Test sooner if the well has flooded, if it has been opened for repair, if the water changes in taste, smell or colour, if someone in the household has an unexplained stomach illness, or if you are about to buy the property.
What to test for
- Total coliform and E. coli bacteria. Coliforms suggest that surface water or something else is entering the well. E. coli indicates contamination by human or animal waste, and water that contains it is more likely to carry disease-causing organisms.
- Nitrate-nitrogen. Comes from fertiliser, animal waste and septic systems. Water with nitrate-nitrogen at or above 10 parts per million is not safe for drinking, particularly for infants, because it interferes with the blood's ability to carry oxygen.
- Total dissolved solids (TDS) or salinity. A measure of dissolved minerals; high values taste salty or brackish and can damage plumbing and fixtures.
- pH. Acidic water corrodes pipes.
- Arsenic and other naturally occurring metals. Present in parts of Texas depending on the aquifer; ask your county Extension office or lab whether they are a concern in your area.
Where to get it done
Texas A&M AgriLife Extension holds well screening events in many counties through the Texas Well Owner Network, and the Extension Soil, Water and Forage Testing Laboratory takes mail-in samples. Any lab accredited to test drinking water will also do; ask your county health department or the district. Use the lab's bottle and follow its instructions. A homemade sample from a dirty jar gives a bad answer.
Collecting a sample
- Get the lab's sterile bottle and its instructions before you start.
- Choose a tap close to the well, before any treatment device, and remove aerators.
- Wash your hands and run the water for the time the lab specifies.
- Fill the bottle without touching the inside of the cap or bottle.
- Keep the sample cool and deliver it within the lab's time limit, often within 24 hours for bacteria.
Reading the result
A positive bacteria test does not always mean the well is ruined. The usual response is to have the wellhead inspected (cracked casing, missing sanitary seal, nearby septic or livestock), disinfect (shock chlorinate) the well and system, and retest. If it keeps testing positive, ask a licensed driller or pump installer to inspect the well; a TDLR-licensed professional can do the repair work. High nitrate needs a different fix: a new source, or an appropriate treatment system for drinking water, chosen with a lab's advice.
New wells
Have a bacteria and full chemical analysis done on a new well after the driller has disinfected it and before you drink the water. Ask the driller to include disinfection and a yield test in the quote.
Keep a record
File your lab reports with your copy of the State Well Report. A run of results over years helps you spot changes early, and it helps a buyer of your property.
For more, see the Texas Well Owner Network (AgriLife Extension) and TCEQ's private well pages at tceq.texas.gov.