Households across London and south east England have been told to use as little water as possible, after extreme weather caused burst pipes.
Thames Water said around 12,000 homes were left with no running water following the recent deep freeze and thaw, while several water companies said they were also tackling multiple bursts on their networks.
Thames Water, South East Water, Southern Water and Affinity Water have urged customers who do have running water only to use it where essential.
In a joint statement, they said: "Where possible, take short showers rather than baths, do not leave taps running unnecessarily and only run washing machines and dish washers when you have a full load.
"This will make a real difference."
Companies handed out bottled water to affected customers over the weekend, while one school in Streatham, south London, said it would not open on Monday due to a lack of water on site.
A tweet from the Dunraven School said: "We'd hoped things would have been resolved by now. No water on either site means we can't open the school. We will update families when we can."
The barrage of snow which struck the UK last week may be thawing in many parts, but the repercussions are still being felt across the country.
A flood warning is in force for parts of Halesworth in Suffolk, with rainfall and melting snow causing danger. Meanwhile 33 flood alerts are in place, largely concentrated in the west of England and Wales.
Temperatures rose above freezing over the weekend after the Beast from the East and Storm Emma brought a deep cold snap during last week - which saw the first day of spring according to the meteorological calendar.
The mercury is predicted to hit 11 degrees celsius in London today (March 5) but weather warnings for snow and ice are still in place for parts of north England, Northern Ireland and Scotland.
Met Eireann has yellow and orange alerts in place for snow and ice which run until midday today (March 5).