Scotland’s reservoir levels currently sit at just 66 per cent of their capacity - the lowest on record for this time of year - according to Scottish Water.
The corporation warned that, although demand for water has eased in recent weeks, it remains up to 100 million litres per day above average.
It comes amid the second driest summer in Scotland for more than 150 years, with more dry and warm weather predicted for next week.
Forecasters also believe further length dry spells lie ahead in October and November.
Scottish Water said Scots can protect normal water supplies by using water efficiently around their home - including by turning off the tap when brushing teeth, and using a watering can instead of a garden hose when tending to plants.
It also recommended avoiding paddling pools, which require an average of 400 litres of water, and not using jet washers, which use an average of 36 litres of water.
Despite the warning, Scottish Water insisted there was no suggestion that restrictions on water usage might be imposed.
Kes Juskowiak, Scottish Water’s Water Operations General Manager, said: “People might assume that, because we are at the end of summer, Scottish schools are back and there has been some heavy rain recently, there is no longer an issue with water supplies.
“That is absolutely not the case and maintaining normal supplies remains a massive challenge for us.
“We thank customers for using water efficiently when we asked back in July as we did see a reduction in the spike of over 200 million litres extra being supplied each day.
“However, demand remains between 50 and 100 million litres higher each day than the average for this time of year and our water storage and resources are low due to the continued generally dry weather.”
He added: “We can’t do anything about the low rainfall, but customers can continue to help us by using water efficiently.
“If people across the country - residents and visitors or holidaymakers - can take some small, simple steps to reduce their water use, they can make a big contribution towards our efforts to maintain normal supplies for everyone.”