Doctors in Townsville are reassuring residents that the tap water is safe to drink despite it being a strange colour.

Some residents have raised concerns with the Council about yellowish water coming from their taps.

The General Manager of Townsville Water, Scott Moorhead says the problem started after an outbreak of blue green algae in the Ross River Dam.

"The amount of algae coming through from the dam is clogging the filters and slowing down the treatment process,” Mr Moorhead says.

The Council changed the depth at which it took water from the dam to reduce the amount of algae and minerals getting into the system.

But the intake picked up some sediment containing iron oxide and magnesium which is causing discolouration.

Mayor Jenny Hill says that has now been fixed and another step has been added to the water treatment process to fix the discolouration.

"That will take about up to seven days to work its way through our whole system," Councillor Hill says.

Director of the Townsville Public Health, Doctor Steven Donohue says discolouration happens from time to time but the water is safe to drink.

"We're very confident that all of the water in Townsville meets Australian Drinking Water Guidelines," Doctor Donohue says.

He says the amount of minerals and leaves in the water are tiny and "have no effect on human health."

Mayor Hill says the Council maintains the plant and regularly tests the water.

"We have our own laboratory to test it...we've even had Queensland Health double checking the results, the water is fine," Councillor Hill says.

The Mayor says the water at her home is discoloured and she has been drinking it.

Blue-green algal blooms are a common issue, caused by an influx of nutrients being washed into the dam at the start of the wet season combined with warmer temperatures.