Scots are being urged to shun paddling pools, jet washers and garden hoses to protect water supplies during the heatwave.
An extra 200 million litres of water per day is being produced to cope with the spike in demand during the sweltering temperatures, said Scottish Water.
That is enough to fill nearly 2.4 million baths, the publicly owned water company said.
The company added it was having to drive water-filled tankers to some parts to maintain normal levels, including East Neuk in Fife, Portavadie in Argyll and parts of Skye, Orkney, and Dornoch in the Highlands.
Kes Juskowiak, Scottish Water’s water operations general manager, said reservoir levels have dropped to 74% from 77% last week – and 90% in late May.
He said: “These are very challenging conditions because of the warm, dry weather we’ve been experiencing and the forecast for the coming days is for more of the same.
“Current levels are below average for this time of year but the main issue is demand for water from customers, which has increased considerably during the warm weather.
“When garden water use increases dramatically, for things like sprinklers and paddling pools, that places considerable strain across our infrastructure to move the water as quickly as the customers need it.”
He called for people to use watering cans instead of hoses, only use the dishwasher and washing machines when fully loaded, and only partially fill paddling pools, then use the leftover water to water plants.