What is that pong?
Strange smells at Mangere Bridge need to be reported immediately, Watercare says.
Eighteen people contacted the Manukau Courier last month after it ran a story about an unpleasant smell that some say is similar to the pong caused by the wastewater plant in the past.
But Watercare says it needs the community's support to figure out if it's the plant causing the problem.
"If we don't know about the smell, there's nothing we can do," wastewater operations manager Mark Bourne says.
Six people have complained directly to Watercare about the odd odour since the initial story ran.
One or two complaints are received in an average month.
Mr Bourne says a "huge amount of effort" is put into removing unpleasant smells from wastewater and every complaint is investigated.
But he admits the process is not a 100 per cent perfect.
"The reality is we're in the business of treating sewage."
Most of the responses received by the Courier came from people living within a 5km radius of the plant on the western side of Mangere Bridge.
Many complained of a sewage-type smell while others compared it to an unpleasant animal stench.
One resident, who doesn't want to be named, says the smell has got worse in the past few months.
"It's just coming too often."
And another resident says the pong often stops her children from playing outside.
Mangere Bridge Residents and Ratepayers Association secretary Brian Pilkington says the odours are normally isolated to certain parts of the suburb.
"Normally the complaints go straight thorough to the plant and they follow up on them. It depends on the temperature changes, the direction of the wind."
If the plant hasn't been dealing with the smells, people need to complain straightaway so its management knows about it, Mr Pilkington says.
Several things could be causing the problem, Mr Bourne says. The smell might be coming from pumping stations or sewers maintained by Watercare or it could be coming from the shoreline.
A massive effort has been put into eradicating odours since processing was moved from oxidation ponds in the harbour to a land-based system in 2003, Mr Bourne says.
Processing includes the removal of nitrogen in a machine called a reactor-clarifier and the use of ultra-violet light to destroy bacteria and viruses.
Call 442 2222 to report unpleasant smells to Watercare.