Thames Water is readying its new desalination plant in east London to supply water during the drought.
The £270M plant at Beckton was built in 2010 to give the company a back-up source of supply during long periods of low rainfall.
It treats water from the tidal River Thames, and is capable of putting an additional 150M.l of water a day into supply - enough for 1M people.
A Thames Water spokesman told NCE that the plant was being brought up to full operating capacity and will go into supply mode in the next few weeks.
He said that, once it reaches full capacity, the plant can be brought in and out of operation as and when additional supply is needed.
“We built it for occasions like this,” he said, adding that the company is “juggling” all the resources at its disposal to maintain supply to its 14M customers during the drought.
These include a back-up groundwater source in north London, which is topped up with treated water all year round.
It can provide an extra 180M.l of water a day for up to three months.
Thames is one of seven water companies that last week announced plans to impose hosepipe bans from midnight on 4 April until further notice.
The other companies are Southern Water, South East Water, Anglian Water, Sutton and East Surrey, Veolia Central and Veolia South East.