How to Get Rid of Coliform in a Swimming Pool

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Things You'll Need

  • Pool net or scoop

  • pH test kit

  • pH increaser

  • pH decreaser

  • Free chlorine test kit

  • Chlorine-based pool sanitizer

  • Timer

Even crystal clear pool water can harbor disease-causing bacteria.

Coliform is a class of bacteria common in the environment; it is often found in feces. The presence of coliform in water indicates possible contamination with disease-causing bacteria. Coliform can find its way into swimming pools naturally or by contamination from a diaper or a swimmer's diarrhea. Fortunately, you can easily kill it by using chlorine to sanitize the pool and achieve ideal water conditions.


Step 1

Evacuate the pool immediately when contamination is suspected or an accident happens. Remove visible fecal matter using a net or scoop and dispose of it appropriately. Place the used net or scoop into the pool to be disinfected along with the pool.

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Step 2

Check the pH levels with the pH test kit and ensure that they are between 7.2 and 7.5. Adjust the pH using pH increaser or pH decreaser as needed to bring the pH into this range. The pH test kit, pH increaser and pH decreaser are available at pool supply stores and home improvement stores.

Step 3

Check the chlorine level with the chlorine test kit. Add the chlorine-based sanitizer to the pool to bring the free chlorine level to at least the 2 to 3 ppm level. Maintain the chlorine at this level while circulating the water for 30 minutes.

Step 4

Check the pH and chlorine levels again at the end of 30 minutes. If the pH or free chlorine levels are not in range, treat again. It is safe to reopen the pool once the chlorine has stayed above 2 ppm for at least 30 minutes and the chlorine level has fallen to below 3 ppm, if it was elevated beyond that level.


Other bacteria and viruses may take longer to kill or require higher chlorine levels.

Do not drink pool water.

Disease can be spread through contaminated pool water.


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