Water supply improvement programme manager Helen Beaumont presented the option at a Christchurch City Council meeting on Thursday.
She said a number of underground wellheads would need to be taken out of action for the city to have a "greater chance" of its water supply being chlorine-free by next April, the end of the planned 12-month period of water chlorination.
Under the plan, the city would get all of its water from safe, secure and dechlorinated above-ground wellheads, while unsafe underground wellheads would be isolated and fixed.
But with fewer wellheads providing unchlorinated water, ratepayers would be restricted to winter-level water usage for the whole year. Summer usage is double that of winter.
Beaumont said people using water for their gardens and lawns in the summer would be targeted under the scheme.
"The water conservation campaign is certainly one way residents can help us get the chlorine out of the water sooner," city councillor Andrew Turner said.
The staff report also proposed using UV or ozone treatment on the water as an alternative to chlorination, but both options would cost more for ratepayers.
Mayor Lianne Dalziel said she would fight "tooth and nail" for Christchurch to have unchlorinated water.