ILLEGAL pipes connected to Melbourne’s sewerage system increase the risk human waste will spill into creeks. Heavy rainfall over the past few months has flushed water down stormwater drains, some of which are illegally connected to sewers.

The Merri Creek Management Committee and Friends of Merri Creek said the recent sewage spills sent a flood of raw sewage into the creek near where they were weeding.

The team had to abandon their work two weeks ago as human waste overflowed into where they were working. They were ordered to relocate for their health and safety.

Melbourne Water spokeswoman Stephanie Julian said the organisation was aware of a small number of homes that had illegal connections but said the major contributing factor was water getting into ageing underground plumbing.

Merri Creek management parklands team

co-ordinator Ben North said the instances of sewage overflowing into the creek had increased over the past few months.

The nearby Fairfield rain station has recorded more than 255 millimetres of rain this year following Victoria’s wettest summer on record.

Victorian Climate Services manager Dr Harvey Stern said autumn rainfall was likely to be ‘‘close to normal’’ as the La Nina weather

pattern dissipated.

But Mr North said a big part of the issue with overflowing sewage came down to illegally connected drain pipes.

“Quite often people don’t realise they’re connecting stormwater drains into the sewerage … it will add much more water to the sewerage system than it can handle,’’ Mr North said.

“That’s a major problem.”

Friends of Merri Creek secretary Ray Radford said spills were quite common.

‘‘You can see them as you walk along and if you happen to be working near one when it happens it can be unpleasant and smelly.’’

An upgrade of the northern sewerage system is expected to alleviate pressure on the northern suburbs’ system.

Melbourne Water Project director Mike Filby said the $650 million upgrade would virtually eliminate the need to spill sewage into creeks after heavy rain. The project is due to be completed by the end of this year, about six months ahead of schedule.