Seven water companies have introduced restrictions on water use following one of the driest two-year periods on record, with domestic customers facing a £1,000 fine if they use their hosepipe in defiance of the ban.
Thames Water, Southern Water, South East Water, Anglian Water, Sutton and East Surrey, Veolia Central and Veolia South East are bringing in the restrictions today, affecting about 20 million people.
Customers will no longer be able use their hosepipes for watering their gardens, washing cars or boats, hosing down patios and paths and filling swimming pools, ponds, fountains and paddling pools. Public parks and allotments will also be hit.
The firms insist they are necessary to preserve essential water supplies and protect the environment, in the face of drought which has left groundwater below 1976 levels in some places and rivers running dry.
South East Water has appealed to its customers to help them through the drought.
The Environment Agency said most reservoirs were now below normal levels and river flows were decreasing. All rivers are experiencing lower than normal flows, with two-thirds "exceptionally" low.
The water firms bringing in restrictions say they are investing significant resources in fixing leaks, moving water resources from wetter to drier areas and encouraging their customers to save water.
But the Environment Agency has urged companies to do more to tackle leakage rates.
Water saving expert Jacob Tompkins spoke to ITV Meridian's Charlotte Wilkins about how to save water in the home after hosepipe bans were enforced in parts of drought-hit Britain.
To listen to Mr Tompkins' advice, click here.
The hosepipe bans means water customers are not permitted to do the following:
Water a garden using a hosepipe
Clean a car using a hosepipe
Fill or maintain a domestic swimming pool
Fill or maintain a domestic pond
Fill a fountain
Hose down a path, patio or artificial outdoor surface using a hosepipe
Water plants using a hosepipe
The Environment Agency called for businesses, as well as householders, to save water, warning hosepipe bans for residents were effective, but "not a silver bullet".
Trevor Bishop, head of water resources at the government agency, said: "While households have a very important role to play in helping to cut water use during the current drought, businesses, farmers and water companies must all play their part too, by using water wisely to ensure that the water that we do have goes further."