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Keeping Your Swimming Pool and Spa Healthy

Environmental Health Guide

A swimming pool or spa can be an asset to your home, and provide the opportunity to take part in healthy relaxing activities.

However, with this opportunity comes the responsibility to ensure the swimming pool or spa is safe to use.

Water Treatment

Swimming pool and spa water is continually contaminated by dirt, chemicals, microorganisms and other pollutants which can make the water unsafe to swim in.

The microorganisms can produce infections and illnesses in bathers, including infections and illnesses in bathers, including the fatal disease Amoebic Meningitis.

Water treatment includes filtration and chemical disinfection.


The purpose of filtration is to remove dirt and other suspended material from the water. Common types of filters include sand filters, diatomaceous earth and cartridge filters.

The filter system should have the ability to completely filter all of the water in a swimming pool within 6—8 hours, and spa pools within 30 minutes — 1 hour.

Always ensure the filtration system is operating when there are swimmers in the pool or spa and for at least one hour after the last bather gets out. As a filter operates, dirt builds up inside it, and needs to be removed. It is important to ensure filters are regularly cleaned to enable them to operate at maximum efficiency.

Many filter systems have a built in pressure gauge that shows the pressure levels inside the filter. Whenever the pressure levels increase, it indicates that the filter is becoming dirty and will need cleaning.

Systems that do not have pressure gauges should be cleaned whenever the flow of water from the filter back into the pool or spa noticeably decreases.

Sand filters are generally cleaned by backwashing. Diatomaceous earth filters are cleaned by either backwashing or manual cleaning, and cartridge filters are cleaned manually. All filters should be cleaned in accordance with the manufacturer’s instructions.


To prevent transmission of infections, it is necessary to add a chemical to the water that can destroy microorganisms. The chemical must be able to rapidly destroy microorganisms in the water and oxidise chemical pollutants, without harming the bathers. Chemical disinfection processes all involve a chlorine or bromine compound, as they are the most effective chemicals which can be safely used in a swimming pool or spa pool.