Guernsey Water say the exceptionally dry spring and hot start to the summer are putting supplies under pressure.
Islanders are being asked, and at this stage not told, to stop watering their lawns or cleaning their cars with tap water.
Instead, Guernsey Water wants people to save supplies by watering plants and lawns with waste kitchen or bathroom water.
It comes after an exceptionally dry spring and early summer, with no sign of a let up in the hot dry conditions and that is putting supplies 'under pressure.'
Le Vardes quarry on Guernsey's west coast which will become the island's next reservoir, but not for a decade.
On 30th June, the mercury hit 30.4C in Guernsey and water usage reflected that, with 15.4 million litres used.
Guernsey Met figures for June show the month was just short of a record breaker in terms of average daytime temperatures, and it was drier than usual.
There was sporadic overnight rainfall in early July and some at the weekend. Nevertheless, the amount Guernsey Water stored was 58 million litres verses demand of 91 million litres.
The utility says it would not expect to begin July with full storage, but at this stage it is about half a month's worth of water short, around 200 million litres.
Guernsey did not impose water restrictions in the last dry summer of 2022 whereas Jersey did.
The message to islanders is change your water use habits and if everyone saves a little, then that adds up to a lot.
Eight Guernsey football teams to compete for the inaugural Spirit Cup
June brought near-record-breaking heat to Guernsey
New Post Office opens in Guernsey
Guernsey students surpass global average IB results
Newcomers swell committee ranks
Strong winds stop yacht race from getting to Guernsey
Unusual Find: Squash spotted in St Martins douit
Guernsey students' “Rubbish Idea” wins UK tech award
