Seven water companies across southern and eastern England have issued hosepipe bans that have come into effect since midnight.
Southern Water, South East Water, Thames Water, Anglican Water, Sutton and East Surrey, Veolia Central and Veolia South East have all banned their customers from using hosepipes.
Together the companies are responsible for providing water for 20 million people.
The restrictions have hit just in time for Easter weekend and anyone caught breaking the ban could face a fine of up to £1,000.
From today, around 20 million people will not be permitted to do the following:
Water a garden using a hosepipe
Clean a car using a hosepipe
Clean a boat 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
There are some exceptions:
Sports fields that host "national or international" events are not affected
Some cleaning businesses, such as window cleaners and car washes, will be allowed to continue to use hosepipes
If it is necessary "for health and safety purposes" a hosepipe can be used to clean an outside surface
Drip or trickle irrigation watering systems that are fitted with a pressure valve and timer, and are not handheld, are still permitted
Anyone with severe mobility problems, and anyone who holds a current 'Blue Badge' issued by their local authority, will be not be subject to the restrictions
The ban comes as the Environment Agency announced that parts of Yorkshire have now officially entered a drought.
It has urged the public to do all it can to use less water.
East and south Yorkshire from Chesterfield to Scarborough are officially in drought.
They join the south-east and east of England, most of which has been in drought since late last year, although areas of East Anglia have been suffering since last summer. Click here for more coverage from ITV Anglia.
The blue lines in the map below shows the areas of south and east England currently experiencing drought.
Many of the main rivers of south and east England are very low for this time of year, including the River Don, Rother, Hull and Derwent.
Richard Benyon, Parliamentary Under-Secretary for National Environment and Fisheries, said the ban was necessary to manage the shrinking water resources.
He described the situation as "unprecedented" for this time of year.