Melbourne Water has been fined $400,000 over the workplace death of a technician who drowned in a sewerage channel in what a judge labelled a "clear and substantial failure" of ensuring a workplace was safe.


It is suspected Tim Bakerov fell into a channel at the Eastern Treatment Plant in Bangholme either because a metal covering grate was missing or it gave way after being dislodged the previous night by a surge of aerated sludge inside the channel.


Mr Bakerov had collected a sample from the channel for analysis before he fell on the morning of December 1, 2011.


After the channel was drained, the 53-year-old's body was found about 150 metres from where he had left his equipment. The grate that had fallen was also discovered, along with two other grates that had fallen previously.


The death of Mr Bakerov, a father of three girls, came after grates were discovered either dislodged or missing from channels at the plant.


Judge Chris O'Neill told the County Court there had been a "sufficient number of occasions" dating back to 2008 where grates had either been dislodged or gone missing, and that it was disappointing and tragic they were had not been permanently fixed much earlier.


"As events subsequently showed, it was a simple and inexpensive task to secure them to the concrete," he said on Thursday.


Judge O'Neill said Melbourne Water's failure to secure the grates permanently was a "clear and substantial failure, in particular in a workplace where there were considerable hazards, and occupational health and safety matters were said to be important".


Melbourne Water last week pleaded guilty to one charge of failing to provide or maintain a safe working environment.


Judge O'Neill said Melbourne Water's failure was in the medium range of offending under workplace health and safety laws. The corporation faced a maximum fine of $1.1 million.


Judge O'Neill said Melbourne Water took immediate steps to secure the grates after Mr Bakerov's death and published details of the incident and its response to alert other water authorities.


The judge acknowledged the penalty would not bring much solace to Mr Bakerov's wife and daughters given the tragic circumstances of his death and the grief they would experience for the rest of their lives.


Melbourne Water chairman Paul Clark said the organisation had been shocked and saddened by Mr Bakerov's death and had done everything possible to prevent other tragedies.


"We recognise the devastating impact of this tragic incident and sincerely express our condolences to Tim's family and friends," Mr Clark said in a statement.