HEALTH authorities have warned North Coast residents with rainwater tanks to avoid illness with routine maintenance of the roof, gutters and pipes.

NSW Health has gone so far as to advise homes with tanks to boil the water first or use town water where available.

Senior environmental health officer Tony Kohlenberg said regular maintenance would also improve the taste, colour and smell of the water.

"Extra maintenance of the tank, roof, gutters and pipe work particularly before heavy rain seasons, is important for a safe supply of drinking water," said Mr Kohlenberg.

"Rain water from the tap can be disinfected by bringing the water to a rolling boil and allowing it to cool before drinking or diluted chlorine can be added to the tank water to kill any bacteria."

He said public water supplies were the most reliable source of clean drinking water and tanks should be primarily used for non-drinking purposes.

"It is very important for tanks to include a first flush diversion device and gutter guards so avoiding the first portion of roof run-off from entering the tank," Mr Kohlenberg said.

"This can help reduce the amount of dust, animal droppings, leaves and so on, from being washed into tanks."

Tips for cleaner tank water:

At least every three months:

- Inspect and clean gutters, roof and leaf strainer

- Repair and seal any cracks, holes or other damage to tank

- Clean mosquito screens and check tank access points

- Inspect water in tank for presence of animals, mosquitoes and other bugs.

Every six months:

- Remove overhanging branches where possible

- Check for and repair any leaks in pipe work and pump

- Check the structural stability of the tank.

Every 2-3 years:

- Remove sludge by siphon or by complete emptying and cleaning of the tank - for your safety, use a professional tank cleaner.

A brochure about maintaining your rainwater tank is available here.