When a well test comes back positive

Stop drinking the water and retest to confirm. Then, following Texas A&M AgriLife's order, find the source and fix it, disinfect the well, and test again. Disinfecting before the cause is fixed skips the step most likely to keep the bacteria from coming back.

8-1 What the result is saying

Chapter 7 was about getting a clean sample. If yours came back positive, read the lab's report for which test it was, because the words matter.

Coliform bacteria are very common, and a positive for coliform alone does not necessarily mean the water has met human or animal waste. AgriLife is firmer on the other two. Fecal coliform or E. coli "definitely indicates contamination" by contact with waste.¹ Either way, the next steps start the same.

8-2 Five steps, in the order AgriLife gives them

Texas A&M AgriLife's publication SCSC-PU-146, from May 2023, lists them in this order.¹ The order is the useful part.

8-3 What to drink in the meantime

AgriLife says to use bottled water for drinking and cooking. If you have none, boil what you use for drinking, cooking and brushing your teeth.¹ Boiling is for germs. EPA says it will not reduce nitrate, so a nitrate problem stays a separate question, as Chapter 7 explains.⁹

Boil times differ by publication. ESC-059 says one minute, an older AgriLife sheet says five, and TCEQ's notices for public systems say a vigorous boil for two minutes.²³⁴ This book uses TCEQ's two minutes. Use at least two minutes unless your notice or lab instructions give a longer time.

ESC-059 also says contaminated water should not go to making ice, bathing, or washing clothes and dishes.² That reaches further than people first expect, and it is one more reason to move through the steps instead of waiting on them.

8-4 Looking for the way in

AgriLife's list of places to check is short: a faulty wellhead or poor construction, a shallow well or one near surface water, an old or abandoned well, a septic system, or another concentrated source.¹ Figure 8-1 shows the first place to look, because you can see it without tools.

AgriLife's well guide says to look at the wellhead monthly for breakage, soil disturbed by burrowing animals, or flooding. It says the owner can repair and maintain the pad, and a licensed contractor should repair broken casing.⁵ An old well nearby deserves a walk of its own, and Chapter 11 covers what the law then expects of you.

A septic system is the one you look at from the outside only. Never open a tank, and never lean into or enter a tank or pit, because the gases can kill quickly. Lids stay secure. If you suspect the system, the work goes to licensed people, and Chapter 26 covers the signs that can be read from the yard. TDLR's distances between wells and septic parts are 50 feet from a tank and 100 feet from drain fields or spray areas, so a measurement from the surface tells you how close yours sits.⁶

8-5 ESC-059's chlorine figures

These figures come from ESC-059, published by Texas A&M AgriLife in August 2019.² AgriLife's publications differ from one another. ER-011, from 2006, gives different times, and a version on the Texas Help site differs again.³⁷ AgriLife also lists a January 2022 publication of the same title, seen here only as an overview.⁸ Get the current AgriLife publication or your lab's instructions and follow them as written. Treat this table as a way to see the scale of the job, not as the whole method.

ESC-059 is written for wells with a properly functioning submersible pump only. It says its method will not work with a jet pump or a damaged system. The bleach it calls for is unscented household liquid bleach less than 6 months old. Water depth is total well depth minus the static water level, and if you do not know that level, it says to use the total depth.

The table states no bleach strength, and household bleach is sold at different strengths, so ask the lab or AgriLife before relying on the cups shown.

ESC-059 warns that too much chlorine is harmful and says to follow its table carefully. It carries the bleach in a bucket of bottled water. Softeners and filters go to bypass, and power goes off at the breaker before the well is opened. If your well does not look like the ones it pictures, it says to call a contractor. A breaker reached from dry ground is as far as this book goes with electricity. Any pump wiring goes to a licensed person.

The chlorinated water then circulates through a hose into the casing for 30 minutes. It is drawn to every tap, hot and cold, until you smell bleach, and left in the plumbing for at least 8 hours or overnight. Flushing goes through a hose, kept away from the septic system, landscaping and bodies of water. ESC-059's last word is the one that counts: no drinking until the water has been tested.

SCSC-PU-146 advises hiring a licensed driller or pump installer for this, to cut your exposure to hazardous chemicals and protect the well's parts.¹ Chapter 6 covered how to check that license through TDLR's search.

8-6 After a clean result

AgriLife says to retest in 6 months to a year after a negative result, and at least yearly from then on.¹ If the positive returns, the source was not found. Go back to step 3, not step 4.