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Good housekeeping is the key to controlling and reducing the risk of infection in pools and spas. High-level organic contamination reduces chemical disinfectant levels which can result in the need to increase chemical dosing to maintain the right chemical balance.

Microbiological testing

Microbiological tests provide a ‘cross check’ or a ‘health check’ to see whether the water treatment system is functioning correctly. The British Standard Institute recommends that testing should take place in the following intervals:
– Before a pool is used for the first time or after refilling
– On a monthly basis
– If the water treatment methods are changed
– In the event of any health problems
– Following gross contamination events
– Following major works to treatment system

Water samples

Water samples should be analysed by a recognised UK Accreditation Scheme (UKAS) laboratory. The process and it involves adding the water to a Petri dish containing a nutrient medium which is then incubated at body temperature for 48hours. This is to encourage any bacteria multiply to form colonies that can be easily identified and counted using microscope and ultraviolet technology.

There are a variety of microbiological tests carried out, some of which establish the total number of bacteria (or a specific group of bacteria) present. Others identify particular species of bacteria that are harmful to bathers, and which are likely to occur in swimming pool water.


Contaminated pools can contain dangerous microorganisms which can cause a range of ailments to pool users, ranging from mild skin irritations through to serious bacterial infections.
Bacteriological testing aims to identify harmful pathogens and bacteria in the pool water, which can be introduced to pool water by users or by poorly maintained plant equipment and pool structures.
Pools should be closed following bacteriological tests if:
– The result suggests gross contamination
– There is chemical or physical evidence that the pool disinfection system doesn’t operate correctly
If there is evidence of gross contamination, the local Consultant for Communicable Disease Control should be notified and the pool should be closed to prevent illness.

Alzach Leisure Consulting

Alzach provides bacteriological testing services for pools, carried out in accordance with the BSI Code of Practice PAS39:2003. Our testing service provides regular monitoring and reassurance to pool operators. We will carry out testing and provide full laboratory reports for your records. If any potential issues are identified, we will work with you to mitigate risks and carry out work which will remove or reduce dangerous organisms to safe levels.

Keep your pool safe for users. Contact us today.