Scottish Water revealed it is using 30 tankers a day to transport water to areas where supplies are running short.
Arran, off the Ayrshire coast, has received three-quarters of a million litres extra, thanks to a fleet of tankers sent by ferry to the island, where it is believed holidaymakers have caused a drain on resources.
The water supply has also been boosted further north, in Moray, the North-east and Dornoch.
Peter Farrer, Scottish Water’s chief operating officer, said: “We are working around the clock to maintain supplies during this period of very warm, dry weather which is having an effect on the amount of water people are using for a wide range of purposes.
“Our tanker operations are an important part of our response to the current challenges.
“We remain absolutely focused on ensuring Scotland’s water supplies are maintained and protected but I would repeat the call to customers to work with us to achieve this.
“We have seen unprecedented increases in water use across the country where there has been very little or no rainfall for weeks and our teams are working at near capacity to meet that need.
“Customers can help reduce usage levels by taking some simple but important steps to use water wisely and efficiently at the present time and I urge everyone to think about the water they use in and around their homes.”
However the Met Office has now warned that Tropical Storm Chris, currently battering South Carolina in the US, is heading towards Scotland for Sunday.
Forecaster Nicky Maxey said Chris is expected to strengthen to hurricane force before making its way across the Atlantic.
The exact path it takes across the Atlantic is uncertain, with one theory taking it towards southern Europe and the other towards Scotland.
Ms Maxey said: “There is the potential for it arriving as a low pressure system in the UK later on Sunday.
“This could bring wind and rain to Scotland on Sunday into Monday.
“Chris will lose much of his energy as it crosses the Atlantic but it will present something of a change to the weather we have been enjoying for weeks.”
Today will see some rain, heavy in the south west of Scotland during this morning’s rush hour. Thunderstorms could affect the same area on Friday.
Meanwhile, insurance companies are braced for a spike in claims for subsidence as building foundations start to shift in the heatwave.
During the last period of very hot and dry conditions, in 2003, firms paid out an estimated £375 million to rectify structural faults.
Simon Pitchers of The Institution of Structural Engineers said: “Heatwaves can cause subsidence – but only if a building is founded on shrinkable clay.
“Trees are biological pumps, sucking water from the ground and then dispersing it into the atmosphere. In heatwaves, there is very little water going back into the ground but trees still need water. They will start to take water from soil that is deeper and further away from them.”