Katikati's sewer outfall has been damaged by one of the containers washed ashore along by beach from the wreck of the container ship Rena.

Divers inspected the outfall offshore from Matakana Island after damage was suspected on Friday.

'The container has done some damage to the outlet structure where the outfall discharges into the sea, but it's not interfering with the flow,” says Western BOP District Council water utilities operations manager Peter Edwards.

The inspection was ordered after it was thought a blockage could be contributing to an apparent drop in the 10km outfall pipe's capacity.

The pipeline crosses under the harbour from Katikati, under Matakana Island and discharges into the sea off the beach

The dive to inspect the outfall was made in very poor visibility with a lot of stirred up sand and silt making the inspection difficult. But what the diver found appears to be only cosmetic damage says Peter.

'We will send them back next week when the weather is clearer, and we will have a look and see,” says Peter.

The inspection was ordered as part of the steps taken last week to prevent a possible overflow at the Katikati wastewater treatment plant. Heavy rain since Christmas and a suspected drop in pumping capacity, required the ordering in of a convoy of sucker trucks to remove about 1000 cubic metres of waste water from the plant's treatment pond and wetlands.