A $7 million project to install a new wastewater system in Canterbury will be delayed as the Christchurch City Council finds ways to get out of its huge financial hole.

Around 160 Wainui residents have been waiting for the development, which means they'll no longer have to rely on septic tanks and long drops to manage effluent.

Akaroa-Waiwera community board chair Pam Richardson says the decision is disappointing.

"Many of them have held back doing upgrades to their own homes, developers have looked at hanging on until the new system comes on.

"There's a whole lot of things."

Richardson says it'll mean residents are stuck with costly septic tanks and long drops for longer.

"Up to $25,000 put in. They need to be maintained, emptied regularly and some of the newer systems, they cost $500 every six months."

Residents are being consulted on future options.