United Utilities are urging residents in the North West to save water by not taking baths and limiting showering to four minutes.
The water supplier says that the region's supply of tap water is less than half what it should be at this time of year and levels have dropped again in the last week.
The water comes from Haweswater and Thirlmere reservoirs in the Lake District which are currently only 36% full.
Usual levels in September would be around 70%.
Although there have been some wetter days in North West cities and towns and even flooding in some areas, it has been the driest June to September in over 130 years in the Lake District.
In an email to customers, United Utilities said:
The supplier delivers nearly two billion litres of water a day to more than three million homes and businesses in the region.