It is understood the child, about seven years old, was affected by bacteria in the small inflatable 'splasher', which had not been cleaned in several days.

Health Department acting director of environmental health Brian Devine said it was important water in the wading pools was changed after every use.

Mandurah City Council has also issued a warning to prevent infection by emptying, scrubbing and allowing the pools to dry in the sun after each use.

With hot temperatures continuing, pool owners across the State are being reminded to prevent the potentially deadly amoebic meningitis.

"Sustained hot weather means some pool temperatures will reach and exceed 28 degrees Celsius, creating ideal conditions for amoeba to develop," Mr Devine said.

"If water containing amoeba goes up the nose, it can lead to the serious illness- amoebic meningitis."

Swimming in suspect water such as dirty pools, water holes and dams was not recommended.

Mandurah City is continuing to ensure pools comply with regulations.

Pool areas should be checked regularly for cracks or holes, which are tripping hazards and places where bacteria can accumulate,

Tips for pool owners

Ensure pools are kept clean, free of dirt and leaves, and properly chlorinated.

Water in swimming pools should be tested at least twice a day.

Where stabiliser is not used, water should contain at least 2mg/l of chlorine and 4mg/l where stabiliser is used.

pH levels should be kept between 7.2 and 7.6.