Residents of flood-hit areas in England have been told not to panic as a massive operation takes place to get clean water to those left stranded.
People are being offered emergency bottled water
Emergency services have been battling to deliver supplies to the 350,000 people across Gloucestershire without running water since Sunday.
Police urged calm, saying there was enough water for everyone.
Meanwhile, homes in west Oxford have begun to flood and water is being pumped from an electricity substation.
The flooding from the River Thames started late on Tuesday as the river was still rising and it is not expected to peak in the city until lunchtime on Wednesday.
The Osney Mead substation supplies power to Oxford city centre, although Oxfordshire Fire and Rescue Service said supplies to some business premises had already been re-routed.
The service's John Lloyd said: "We've got a steady but constant rise of flood water levels within Oxford city centre, particularly on the western side of the city.
"It's starting to affect areas which haven't been affected before and in particular one electrical substation which does control a lot of the power to some of the more essential premises, for example the hospitals. So some concern over that area there."
He said it was expected that supply would be lost at some stage later in the day.
Homeowners in Berkshire are also braced for more floods as the Thames is yet to peak in Pangbourne, Purley on Thames and Reading.
Environment Secretary Hilary Benn earlier warned that the emergency was "still not over" and that flooding of further properties along the Thames may be "unavoidable".
He pledged to add a further £10m to the current £14m recovery fund available to local authorities to help with the aftermath of the worst flooding for more than 60 years.
Six severe flood warnings remain in place across western England. Forecasters say more showers are expected across England throughout the week, with heavy rainfall predicted for Thursday.
The Environment Agency warned water levels could rise again and urged people to stay alert.
The Queen sent her sympathies to all those affected, saying she was "shocked and deeply concerned" by the devastation caused.
She also sent her "heartfelt thanks" and expressed her "continued admiration" for the emergency services, military personnel, local authorities, and volunteers working "tirelessly and selflessly to bring people to safety and avert further damage".
While flood waters have been receding in areas of Gloucestershire, parts of Gloucester and Tewkesbury - the two worst hit areas - remain under water.
As many as 900 bowsers - mobile water dispensers - will be mobilised in the county by Wednesday morning to provide essential supplies.
The Army is also delivering three million bottles of water a day, distributed from Cheltenham Racecourse.
Chief executive of Gloucestershire County Council Peter Bungard said: "I'm really, really worried - 350,000 people is hard to imagine, and amongst those are very vulnerable people."
Gloucester resident Peter Bileman told the BBC he had tried 11 bowsers before finding one with any water in it.
And the county council said several bowsers had been vandalised amid frustrations over supply.
There are further fears residents in northern parts of nearby Stroud could also lose running water because a crucial reservoir is running dry.
Gloucestershire Police Chief Constable Tim Brain said normal supplies might not be restored for up to 14 days but advised people to remain calm.
"It is important that people continue to conserve their own domestic supplies and do not panic in respect of getting water from the bowsers, or from the bottle treatment centres or from commercial outlets," he said.
"If people act calmly and with patience and forbearance, there is sufficient water for everybody."
Up to 48,000 homes in Gloucester had their electricity supplies restored on Tuesday following repairs to the flooded Castlemeads electricity substation.
And Ch Con Brain praised the "super-human" effort which had prevented flood water breaching the walls of another of Gloucester's substations, Walham, which serves 250,000 people.
Emergency services have been trying to gain access to Tewkesbury's Mythe water treatment works to return water supplies to 350,000 people in Tewkesbury, Gloucester and Cheltenham.
During the current crisis, up to 10,000 homes have either been flooded or are at risk of flooding in Worcestershire, Warwickshire, Herefordshire, Lincolnshire, Gloucestershire, Oxfordshire and Berkshire, according to the government.
Parts of Worcestershire remain under water and the Army has been deployed to help emergency services provide supplies to people in Upton-upon-Severn.
The water levels of both the Severn and Thames have exceeded in some areas those of devastating floods in 1947.
The Red Cross has launched an appeal to raise money to help the thousands of people affected by the crisis.
Environment Agency floodline: 0845 988 1188
SEVERE FLOOD WARNINGS IN PLACE
The Severn: Severe warnings for Gloucester, Tewkesbury and Worcester
The Thames: Severe warnings affecting Eynsham to Sandford Lock and also Little Wittenham
The Ock: Severe warnings from Charney Bassett to Abingdon