Swimming Pool Water Treatment: Aerobic Colony Count

Swimming pools are a known origin of infectious agent-induced diseases. In order to ensure that they are kept clean and healthy for consumers, it is important to avoid and monitor the risk of pathogens. To ensure that it stays efficient, the water treatment system should also be routinely checked.

The maintenance of swimming pool water requires routine water quality control and frequent sampling for bacterial presence. Although chemical analysis is critical for measuring the performance of the water treatment system, in order to ensure a full evaluation, it must be carried out along a microbiological examination.

What microbiological tests are needed to be conducted?

An aerobic colony count, coliforms, escherichia coli and pseudomonas aeruginosa should be included in the microbiological testing. These should be performed regularly.

For each, the appropriate thresholds are:

  • Pseudomonas aeruginosa < 10cfu/ml
  • Aerobic colony count < 10cfu/ml
  • E. Coli 0cfu/100ml
  • Total coliforms <10cfu/100ml (if no E.coli is present and colony count less than 10/not)

The water must be measured again if any of the values are outside these levels. If, after a repeat examination, they are still not within the appropriate limit, it means that the pool water treatment does not operate as it should.

For spa pools where hotter temps raise the risk of bacteria, tests for Legionella should also be done once a quarter, or as determined by a risk assessment

In swimming pools and spas, unlike most water schemes used in homes and commercial buildings, the water is not flushed away after each use. The water is held and used several times in swimming pools and spas. This makes it highly important to test the chemical and microbiological consistency of water, as pH and water purity can change over time and microorganisms can begin to develop quickly.