The Council of the Isles of Scilly has warned that the water supply on St Mary's and Bryher is now "critically low".
In a notice published on Tuesday July 17th, it advised that water usage is at a level the islands "can't sustain".
The notice reads: "Due to the extreme dry period this summer, the islands’ groundwater supply is now critically low. Without these vital groundwater sources, we are unable to meet water demand on St Mary’s and Bryher using the desalination plants alone.
"Water usage is now at a level that we can’t sustain. For this reason, we are asking all of our customers to please cease any use of hosepipes and sprinklers and to keep other water usage to an absolute minimum.
"We also ask that everybody checks their water supply for any leaks. A single dripping tap can waste over 5,000 litres of water a year. If you’re unsure about a leak, please don’t hesitate to contact our water team at the details below.
"Just so there is no confusion, you should continue to stay hydrated in the hot weather and drink as much water as you need. We would never ask people to restrict the amount of water they drink."
'Light rain' is next forecast on Saturday July 28th.