Having copped a disappointing summer featuring unswimmable beaches Wellington swimmers enjoying a rare sunny Saturday were forced to retreat yet again after Island Bay's waters turned a suspicious murky brown.

Wellington Water says the water, described by witnesses as stinky, was affected by dirt washing out to sea following a burst pipe in a neighbouring suburb earlier in the day, but people are asked not to swim while investigations are underway.

The water, which was seeping from a pipe that runs into the ocean, was noticed by beach goers about 5pm on Saturday.

A Wellington City Council Facebook post stated a water pipe had burst near Quebec Street in Kingston. Water services to properties along The Ridgeway and Mills Rd were affected.

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Wellington Water spokesman Alex van Paassen said it was likely the burst water main had put extra water into the stormwater pipe, washing dirt out to sea via the outfall pipe.

ISLAND BAY - We're advising everyone to stay out of the water until we've had confirmation that the area is safe. @WgtnWaterNZ drainage team and @greaterwgtn are investigating. Please stay out of the water in the meantime, and we'll post updates as soon as we know more. — Wellington City Council (@WgtnCC) February 15, 2020

Officers had been sent to investigate the damage.

"We've shut the water off, so the discharge will clear, and we'll get on with fixing the pipe as soon as possible," van Paassen said.

"The [incident] is actually a really good example of why you need to be careful swimming near stormwater pitfalls after rain. You can see how the runoff dispersed into the sea."

SUPPLIED The water began leaking from a pipe on Saturday afternoon.

On social media Wellington City Council advised beach goers to stay out of the water until it was confirmed safe.

Island Bay swimmer Andrew Feasey said a sulphurous smell wafted across the beach and crowds fled shortly after.

"You'd get a whiff of it, then it'd clear and be back five minutes later. It was a great way to clear the beach on a Saturday afternoon."

Feasy said there hadn't been any rain in the area.

Previously beach goers were warned not to swim over New Year because of sewerage contamination.

ROSS GIBLIN/STUFF Up to 100 litres of contaminated water per second gushed into Wellington Harbour after a wastewater tunnel collapsed in Willis St.

In the lead up to Christmas Day a wastewater pipe collapsed beneath Dixon St in the central city. By the time workers had toiled through the night on a stop-gap measure, two swimming pool's worth of wastewater had leaked into the harbour.

Part of Willis St will remain closed until March while Wellington Water fixes the pipe.