Coliform and E. coli Water Testing
American Analytical (AATLS) tests drinking water and well water for total coliform bacteria and E. coli in our Tucson laboratory. We use an EPA-approved automated method that checks each sample continuously and flags a positive result within hours, as soon as bacteria are detected. You get a clear present/absent answer, by email, the moment it is ready.
Why fast bacteria results matter
- Home sales and loans. FHA and VA loans on homes with wells require a bacteria test. A late result can delay a closing; a fast one keeps it on schedule.
- Positive results need action. If E. coli is present, the water should not be drunk until the well is disinfected and retested. Knowing hours sooner means a family stops drinking it sooner.
- Retests after disinfection. After a well is shock-chlorinated, a quick retest confirms the problem is fixed.
What the results mean
| Result | What it means | What to do |
|---|---|---|
| Total coliform absent, E. coli absent | No indicator bacteria found. | Retest once a year, or after flooding, repairs or a change in taste or smell. |
| Total coliform present, E. coli absent | Bacteria from soil or surface water are getting into the system. Usually not a direct health risk, but a sign of a pathway for contamination. | Inspect the well cap and seal, disinfect, and retest. |
| E. coli present | Fecal contamination. The water is not safe to drink. | Use bottled or boiled water, disinfect the well, and retest before drinking again. |
Who we test for
- Private well owners and households
- Home buyers, sellers, lenders and inspectors (FHA and VA well water requirements). See water testing for Arizona real estate transactions.
- Small public water systems, schools and daycares
- Facilities, property managers and construction projects (new or repaired lines)
How it works
- Order a kit online or pick one up at our Tucson lab. Each kit contains a sterile bottle with preservative, instructions and a chain-of-custody form.
- Collect the sample from a cold-water tap, following the kit instructions. Don’t rinse the bottle.
- Keep the sample cold and get it to us quickly: drinking-water bacteria samples must be analysed within 30 hours of collection. Drop it off in Tucson or ship it overnight.
- Results are emailed as soon as they are final. Positive results are called in the same day.
Accreditation and methods
AATLS is ISO/IEC 17025 accredited through ANAB (certificate AT-3321), licensed by the Arizona Department of Health Services (AZ0838) and registered for EPA CMDP electronic reporting. Total coliform and E. coli by SM 9223B are on our ISO/IEC 17025 scope. If you need results for regulatory compliance reporting, tell us when you order and we will confirm the method that applies. See all accreditations.
Order a coliform and E. coli kit: order online · see pricing · call (928) 985-9399
Frequently asked questions
How long does a coliform water test take?
With our automated method, positive coliform and E. coli results are flagged within hours, as soon as bacteria are detected, and we call them in the same day. Negative results are reported once the full incubation period is complete. Traditional methods are read only once, at the end of an 18- to 24-hour incubation.
What is the difference between total coliform and E. coli?
Total coliform is a broad group of bacteria found in soil, plants and animal waste. E. coli is one member of that group that lives in the intestines of people and animals, so finding it means fecal contamination. Total coliform shows that contamination can get in; E. coli shows that it has.
Is your coliform method EPA-approved?
Yes. Our method is approved by the U.S. EPA under 40 CFR Part 141 for detecting total coliform and E. coli in drinking water.
How often should I test my well for bacteria?
At least once a year, and again after flooding, well repairs, a new pump, or any change in the water’s taste, colour or smell. Test before buying a home with a well.
Does a home sale on well water need a bacteria test?
FHA and VA loans on properties served by a private well require a water test that includes bacteria. Many lenders and buyers ask for it on conventional loans as well.
What should I do if my water tests positive for E. coli?
Stop drinking the water and use bottled or boiled water. Have the well disinfected (shock chlorination), then retest to confirm it is clear before drinking it again.
How quickly does my sample need to reach the lab?
Drinking-water bacteria samples must be analysed within 30 hours of collection. Keep the sample cold and drop it off or ship it overnight the same day.
More reading: private well water testing guide · lead and copper testing · water testing FAQ