Bosses at Thames Water, South East Water, Southern Water and Affinity Water, which serve Bracknell, Wokingham and Reading, Berkshire, say customers across the south east are either without water or have low pressure.
Tens of thousands in London were left without water or with low water pressure over the weekend as utility firms worked to fix leaking pipes.
He said: "Where possible, take short showers rather than baths, do not leave taps running unnecessarily and only run washing machines and dishwashers when you have a full load".
The company said it was providing bottled water to Wadhurst, Rotherfield, Crowborough, although for a time there was none in Lenham after earlier supplies ran out.
A spokesperson for Thames Water said: "We are really sorry for the ongoing disruption, and we have every available resource working to resolve it as quickly as possible". This will make a real difference.
Homes had been left without water since 1pm yesterday and a water collection point was set up by South East Water.
Customers have also been asked to check their pipes for leaks and bursts and to call a plumber if necessary.
People are being asked to check their own pipes for bursts, particularly outside taps which are vulnerable to freezing temperatures.
The firm said further pipe bursts overnight had caused it to enter peak demand this morning. We are doing all we can to get as many customers back on supply as soon as possible and apologise sincerely to those without water or with low pressure. If they see a leak they can report it to us on our interactive map https://inyourarea.digdat.co.uk/southeastwater where they will also find updates on supply issues in their area. Follow HuffPost UK on Twitter here, and on Facebook here.