THE Gold Coast Desalination Plant will run at increased capacity for the next three months as upgrades are carried out at Mt Crosby.

The plant will provide up to 133 million litres per day into southeast Queensland homes and businesses - the equivalent of 25% of the Brisbane and Ipswich daily drinking water supply - while the Mt Crosby East Bank Water Treatment Plant is undergoing a major upgrade.

Some water will also be diverted from the Sunshine Coast.

Seqwater acting CEO Dan Spiller said the Mt Crosby plants supplied as much as half of the region's daily drinking water.

The Mt Crosby project includes replacing valves, installing a new stand-by generator, design investigations for a planned filter upgrade, and replacing critical infrastructure.

Mr Spiller said the desalination plant was vital to the region's drought response and would be operated at full capacity when the region's dam levels drop to 60%.

During the past three years the desalination plant has been used on a number of occasions as the sole supply for 170,000 residents on the southern Gold Coast while local treatment plants were offline for upgrades and maintenance.