'Disgusting' smell in Auckland blamed on digestion problems and hot summer

South Auckland residents are kicking up a stink over a bad smell. 

Digestion problems at the Māngere Wastewater Treatment Plant are causing the odour, but the weather may also be to blame - the long hot summer causing a bit of a stink itself.

As for what it smells like - residents say it's a "disgusting" odour like sewage and human waste.

Residents in Māngere say they've been smelling it for weeks, and across the harbour in Hillsborough they also sniffed a bad smell on Wednesday.  

The Māngere Wastewater Treatment Plant is the culprit, the plant's manager likening it to eating a lot of KFC. 

"It's similar too if you eat too much food - you can get a bit of an acid stomach," said manager John Piggott.

Watercare says the bad smell was caused by an upset in the balance of bacteria in the eight digesters at the plant.

It says that's nearly back to normal operations, and on Wednesday, its odour scouts measured 'No Detectable Odour'.