The Avon-Otakaro Network is calling on the Christchurch City Council to do more to stop rubbish in the waterways.

Over 700 volunteers from around 40 community, iwi, school, and sports groups and corporate organisations turned out on Saturday for what has been dubbed 'the Mother of all Cleanups.'

They collected almost six tonnes of rubbish from the Avon and Heathcote rivers and the estuary.

Spokesman Evan Smith says they collected less rubbish upstream than in past years.

He says the council has contracts with City Care to clean up the rivers upstream, but they don't have contracts to look after downstream.

Smith says a lot of the rubbish is thrown out of car windows and that ends up in the rivers.

Avon Heathcote Estuary Trust's Tanya Jenkins says it's an enormous amount of rubbish, including bottles, cans, plastic bags, pizza boxes, KFC, and McDonald's.

Jenkins says more education needs to be done to stop littering.