Pool/Spa Testing

Pool/Spa TestingWhy carry out routine microbiological testing of swimming pool waters?

Numerous microorganisms which are potentially harmful to humans can occur in swimming pools and spas. Appropriate management of pool water treatment includes bacterial testing to ensure that bacteria and viruses are eliminated and hence pose no risk to pool users.

In conjunction with chemical testing, regular bacteriological testing gives assurance that operating conditions are satisfactory and provides an early warning system of any deterioration in water quality or failure in the treatment system.

Testing Pool Waters:

Total Coliforms

Coliform bacteria are routinely used as an indicator of water quality, including pool water quality. They provide the most sensitive test for detecting fecal contamination. Because coliforms (in particular E. Coli) are prevalent in the feces of humans and animals and are easily detected, they are used as an indicator of fecal pollution. Where fecal pollution is identified it can be concluded that there is a risk from pathogenic organisms. The Total Coliform group of bacteria represent bacteria of fecal origin and non-fecal (e.g. soil & environmental materials). The presence of Total Coliforms can be considered an indication of risk of fecal contamination, or poor hygiene (e.g. contamination carried in from outside on footware, or leaf debris in outdoor pools). Coliforms are sensitive to disinfection and should be absent in 100 ml of sample. Their presence can indicate that treatment has failed. However, detection of Total Coliforms does not confirm fecal contamination. 

Escherichia Coli (E. Coli) 

E. Coli is present in the feces of humans, mammals and birds. The presence of E. Coli in swimming pool water is an indication that fecal material has entered pool water from contaminated skin, or from fecal material that has accidentally been introduced, or by a contaminated water supply. It also indicates that the treatment has failed to remove this contamination. 

E. Colishould be absent in a 100 ml sample.


Watercheck is a presence/absence test kit for the determination of Total Coliform including E. Coli in water. The format of this presence/absence test conforms to pool safety guidelines since the presence of any bacteria will give a positive response (colour change) and will qualify as a ‘failed test’. The presence of any Coliform or E. Coli bacteria in a pool/spa water sample is an indication that the treatment system has failed to remove contaminants from the pool/spa water.

A single positive sample may be the result of recent superficial contamination by a swimmer that has not yet been disinfected by the residual. Therefore, a repeat sample should always be taken.

**Please see Watercheck™ page for more information on this product.

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