The warning comes from South East Water, which saw record-breaking demand for water when temperatures soared to 36 degrees yesterday (Friday, August 7).
The form said this 'outstripped the amount' which could be pumped through the network.
It added that people's staycations were 'putting a strain' on the country's water network.
As a result, South East Water is asking people to put away their hose pipes, garden sprinklers and garden water toys to help make sure everyone has the water they need to drink, cook, wash and clean with this weekend.
Steve Andrews, head of central operations for South East Water said: “Many people don’t realise that water is a fresh product which is produced 24 hours a day, seven days a week.
“When we draw the water from deep underground or from rivers it has to be treated to a very high standard at our water treatment works before being sent along miles of pipe to homes and businesses.
“Our water technicians have been working round the clock to produce this extra drinking quality water needed – the equivalent of filling to the brim almost half a million baths – but with this record amount of water being used daily it is getting harder to keep up.
“I would like to say thank you to our many water savvy customers who are helping by being water aware, but I am now appealing to every one - household and businesses - to keep water for essential use only while the heat is on this weekend and next week.”
South East Water said the amount of water available in reservoirs and groundwater stores 'continues to be good' but the long, sustained period of hot weather experienced since May has resulted in demand for water remaining high, 'particularly at peak demand times' in the morning and early evening.
It was warned that people filling super-sized paddling pools, hot tubs, using water sprinklers and hosepipes all at the same time adds 'huge pressure' to the normal peak-period demands which can make it difficult to deliver the water quickly enough.
Customers nearer to the water treatment works are using too much leaving very little for the homes and businesses at the end of the pipe leaving them with low pressure or no water at all, the firm said.
Mr Andrews continued: "We are asking everyone to think carefully before turning on the garden tap and also see if they can capture and use the water twice, such as washing hands over a bowl and then using that water on the plants.
“We are also asking them not to wash their cars and leave the lawn to turn golden as it will soon recover when the rain returns next week.
“If filling a paddling pool keep it shallow. I was shocked to be told that the average paddling pool now needs a whopping 530 litres of water to fill them - more than three times the total daily amount of water usually used by one person. This is adding to the high demand for water seen during this hot summer weather.”
Top tips for looking after paddling pool water include:
- Keep the paddling pool covered when not in use to save refilling it as often
- Have a small washing up bowl to clean feet in before getting into the pool will help the water last longer (although easier said than done with kids – but for big kids this will help)
- Don’t fill paddling pools in the early evening when demand for water is higher
- When it comes time to change the water use it on the garden – children can help with this
- Alternatively pour it into a water butt.