"Everything from bathroom products, toys and clothing," the Coliban Water manager of customer operations said.

They are among items which should not enter the sewage system at all, because they can cause costly blockages in the nearly 2000 km of sewer mains Coliban oversees.

Common blockage culprits include sanitary items, ear buds, medication and nappies. Cotton balls, razor blades and even toothbrushes are also often to blame.

"Some products may claim to be flushable, but the truth is that they can take years to break down. Toilet paper takes just 30 seconds to break down. Only 'the three Ps' should be flushed, it's that simple" Mr Dunlop said.

Those three Ps - poo, pee and toilet paper - are the focus of a new awareness campaign to protect the sewage network.

Each year, Coliban Water spends about $1 million repairing and cleaning sewers.

Fats, oils, grease and chemicals also cause problems.

Mr Dunlop said they were not only bad for the environment, but built up to create 'fatbergs' and bound other objects together, which blocked pipes.

Plates should be scraped into the bin or compost and sink strainers should be used to prevent food scraps entering the sewer system.

Residents are advised to check with their council as to what they should do with fats and oils.

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