More than 48,000 homes have had power restored as waters recede in one of the areas worst hit by England's floods.
A Gloucester electricity substation was repaired by emergency services, while at another in the city water levels came close to breaching outside walls.
At least 350,000 people across Gloucestershire have been left without running water because of the floods.
Threatened homes on the Thames escaped flooding overnight, but residents are now on alert further along the river.
Water bowsers installed
Forecasters said more showers were expected across England throughout the week, with heavy rainfall predicted for Thursday.
The Environment Agency said the rainfall could result in water levels rising yet again, causing more misery for homes and businesses.
The government said up to 10,000 homes have either been flooded or are at risk of flooding in Worcestershire, Warwickshire, Herefordshire, Lincolnshire, Gloucestershire, Oxfordshire and Berkshire.
Power was restored overnight to all homes plunged into darkness on Monday when the Castlemeads station was flooded.
And the River Severn peaked below the main quay wall which protects the city centre and Walham substation, which serves 250,000 people.
The fire service and military are still at the Walham site, pumping water into a nearby canal.
Emergency services are also trying to gain access to Tewkesbury's Mythe Water Treatment Works to return water supplies to 140,000 households in Tewkesbury, Gloucester and Cheltenham.
Pumping equipment is being diverted to the water station from the two electricity substations.
Severn Trent Water is aiming to have about 900 bowsers - mobile water dispensers - in place throughout the county by 0600 BST on Wednesday.
About 490 bowsers are already in place, but Gloucester resident Peter Bileman told the BBC he had tried 11 of them before finding one with water in it.
A spokesman for Severn Trent said water supplies were not expected to be fully restored for between seven and 14 days.
The Army said it would distribute three million bottles of water a day until tap supplies were restored.
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."
Tim Brain, chief constable of Gloucestershire Police, urged people to remain calm over water supplies.
He told a press conference: "There is sufficient for personal needs. It is important that people continue to conserve their own domestic supplies and do not panic...
"If people act calmly and with patience and forbearance, there is sufficient water for everybody."
While floodwater levels are dropping, areas in Gloucestershire such as Tewkesbury remain badly flooded.
Water levels in the Thames peaked at Abingdon and Henley in Oxfordshire overnight and at Oxford itself early on Tuesday, with residents escaping flooding.
There are fears several hundred homes could be at risk further along the Thames in Berkshire, which has already been badly affected, and where water levels are not expected to peak until Wednesday.
Tim Abbott, spokesman for the Environment Agency, said: "We are now expecting the Thames to peak in Pangbourne, Purley and the Reading area in the early hours of tomorrow. There could be flooding of some properties.
"Levels in Reading, however, are not expected to be anything like what we have had in Oxfordshire."
The Environment Agency has six severe flood warnings in place - three on the Severn, two on the Thames, and one on the Ock in Oxfordshire.
The water levels of both the Severn and Thames exceeded in some areas those of devastating floods in 1947.
Prime Minister Gordon Brown chaired a meeting of the emergency Cobra committee on Tuesday morning and attended meetings supervising efforts to save the Walham substation.
At the Cobra meeting the possibility of the floods spreading to London was discussed, as well as different contingency plans for the waters moving east.
Parts of Worcestershire are still under water and the Army has been deployed to help emergency services provide supplies to people in Upton-upon-Severn.
A large-scale clean-up is under way in the county to reopen roads closed after the floods.
The Association of British Insurers has said the total bill for the June and July floods could reach at least £2bn.
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
The Great Ouse: Warnings no longer considered severe from Turvey to Sharnbrook