A hosepipe ban has been put in place across a huge swathe of southern England and carries a hefty £1,000 fine.
More than 20 million people will be at risk of a fine if they use hosepipes for cleaning their patio or filling up a paddling pool.
Thames Water, Anglian Water, South East Water, Southern Water, and Sutton and East Surrey Water have brought in the '"Temporary Use Bans".
The companies insist that "drought police" will not be sent to people's homes to inspect their hosepipe usage, but the companies would rather rely on reports to customer services departments of abuse of the regulations.
Households will receive a "yellow card" warning after the first offence, followed by a £1,000 fine if they continue to use a hosepipe.
The Water Management Act has banned 11 activities, including cleaning a private boat, spray-washing a patio before a barbecue, cleaning walls and watering the lawn.
The new regulations were brought in to stop any loopholes which only prevented the use of a hosepipe to water a private garden or wash a private car.
South East Water originally allowed over-65s to use a hosepipe for watering gardens but has joined the other companies by restricting the dispensation to only those with severe mobility problems who hold a blue badge.
Richard Aylard, the director of Thames Water, said people should be able to use their common sense to work out what is unnecessary and therefore banned.
"The point of this is if you do not save water now, it is more likely we will need more severe restrictions later in the year, so you are just cheating on yourself and your neighbours if you waste water," he said.
The hosepipe ban is expected to last throughout the summer, with the drought possibly spreading to the Midlands, South West and Wales.
Hosepipe Ban - What You Can't Do
- Spay patio before barbeque.
- Water the lawn
- Wash your car/windows
- Fill a paddling pool, swimming pool or ornamental fountain.
- Clean a private boat
- Hose down children on a hot day in garden
- Use it for domestic recreational use
- Water plants on domestic or other non-commercial premises
Hosepipe Ban - What You Can Do
- Fill a pond if it has fish in it
- Hose down a path for health and safety reasons. For example, those who keep chickens can spray to remove manure.
- Water the garden with a watering can.
- Wash the car, windows or patio with bucket and mop
- Clean graffiti off a public building
- Fill a home birthing pool