The sight of smoke emanating from sewers around the Tauranga central business district has led to a number of fire call outs in the last week.

Firefighters were called to at least two different incidents in the city by people concerned about white smoke appearing from under manhole covers, and in the middle of streets and vents on buildings.

Firefighters were called to smoking sewers last week.

Council drainage operations engineer Phil Bourke says while the sight is unusual there is an ordinary explanation.

The council is currently undertaking smoke testing in sewers around the city – where smoke is pumped into drains allowing contractors to spot leaks, breaks and places where stormwater can enter the sewer system.

'The purpose behind it all is its part of the council inflow reduction programme for stormwater,” says Phil.

'Just at the moment we are doing the central business district area.”

Contractors City Care has been pumping smoke into the sewers to check for broken pipes or areas where stormwater can enter the sewer system for the last week.

'That's pretty well it for this financial year. We have done some other bits previously, and we will be looking at different areas for the coming year.”

Work will resume work on Thursday and is expected to take another week after that.