Anglian Water said the Whitlingham site deals with tens of thousands of litres of sewage every day.
A spokesperson said: “Due to the nature of the site and the job it’s there to do, there will inevitably be some smells from time to time.
“Keeping odours to a minimum is something we take seriously – especially in the recent heat.”
It has recently installed odour suppression units and an aeration control system, which it said were already reducing bad smells.
Anglian Water is also working to install a chemical curtain, which will suppress odours by using specialist nozzles to control smells.
This project is expected to be completed by December.