Water supplies under pressure from garden sprinklers; PEAK TIME IS WHEN PEOPLE COME HOME FROM WORK.
THEWelsh water network is struggling to cope with demand - but only when gardeners switch on their sprinklers after getting home from work.
So many households are turning on the watering systems in the early evening that pressure in the system is falling massively, the man at the head of Welsh Water revealed yesterday.
While there is no prospect inWales of the kind of water shortages that are expected to lead to hosepipe bans in parts of England later in the summer, the Welsh grid is experiencing short-term problems - because gardeners are hogging all the water.
Automatic sprinklers use more water in an hour than the average family uses in three days, but Welsh gardeners' longing for greener pastures has led to surges in water pressure, meaning that the supply can temporarily run almost dry.
"The demand for water is much higher now at the peak time when people come home from work at night and turn their garden sprinklers on," Welsh Water's managing director Nigel Annett told a meeting of Cardiff Breakfast Club.
"Our network is not designed for that amount of water going through it, which can lead to consumers experiencing lower water pressure levels."
Mr Annett said that while demand for water in Wales has fallen by 25% in the last 10 years, early evening demand has risen.
Wales is not expected to suffer any serious droughts, and Welsh Water has not issued a hosepipe ban for 20 years.
Mr Annett said there was enough water in reservoirs for the summer and the autumn, despite Wales experiencing its driest spring since 1976.
But he warned that the public should restrict its use of water - particularly in the event of foreign travel.
He added: "If there is one thing I would urge our customers not to do it is to go on holiday and leave their sprinkler systems on.
"We can deal with demand, but not for an extended period when people go away for a fewweeks and leave them on."
Gardening expert Terry Walton said the modern trend for installing sprinklers tended to make gardeners lazier.
"Instead of walking round with little watering cans, most people have found it's much easier to sit back and have a drink while these clever little machines do everything for them - but then they go away and completely forget that they're on," he said.
"It's a sign of the times - why get up and do something yourself when a machine can do it for you, and cover a larger area."
The average water consumption for people in Wales is a massive 150 litres a day, but the real culprits may have no clue as to the problems they are causing by flicking on a switch, and simply failing to flick it back off again.
Mr Walton, from Tonypandy, in Rhondda, said: "We don't even need to water gardens that much in Wales. There's so much clay in the ground that stays wet even when the earth seems dry. We're just not used to hot weather in Wales so people panic and water their gardens far more than they need to.
"If you tried to use an automatic sprinkler in the valleys the ground is so steep the water would just wash away anyway, so why bother?" Water companies used to experience their biggest surge at half-time during football and rugby matches, when an entire nation would flick on the kettle for a cup of tea.
Mr Annett said that part of the reason for the fall in total consumption in Wales over the last decade was a decline in heavy industries which traditionally required high water consumption.
But while Wales' gardens and allotments may be blooming, parts of Britain are facing serious water shortages this summer with rumours of hosepipe bans in areas most at risk, especially north-west, south-west and central England.
Automatic sprinklers use more water in an hour than the average family uses in three days - and some people leave them on when they go on holiday