Water storage takes a multi-million-litre hit after successive heatwaves.
June 2026 was Guernsey's warmest June on record, with multiple heatwaves and the highest temperature ever recorded - 36.4 degrees Celsius on 25 June.
Guernsey Water says the heat, combined with limited rainfall, has affected reservoir storage levels.
Over the past six weeks, 180 million litres of water have been collected, but 586 million litres have been used, leaving a deficit of 406 million litres.
A video shared on social media shows water levels at St Saviour's Reservoir falling by a couple of inches.
Guernsey Water is asking islanders to shower for shorter periods and not waste purified tap water on dusty cars or parched lawns.
"We all need to think increasingly seriously about how we’re stretching every drop.
"You are the frontline of our water saving efforts.
"Voluntary individual action repeated by thousands of people makes a collective difference."
Another update is expected in a fortnight.
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