Islanders are being urged to use water "wisely" after the demand during June's heatwave was the highest since the 2022 drought.
Jersey Water said people used 159 million litres (35 million gallons) or nearly 5% of stored water last week as temperatures reached a peak of 39.2C (103F) on Thursday 25 June.
It said water levels at reservoirs at Queen's Valley and Val de la Mare are in a "good position" at 89% capacity but warned it "could drop fast with another heatwave on the horizon".
A spokesperson said water supplies were "finite", with supplies for 120 days when reservoirs were full "so every drop counts".
They urged customers "to use water wisely and avoid waste - small changes by everyone make a big difference".
Jersey Water said its desalination plant at La Rosière, Corbiere, was ready if it needsed to boost supplies and added if islanders cut their water use , externalnow it would "make the quickest difference and help avoid restrictions later in the summer/autumn".
Tips include using water from washing fruit and vegetables for watering plants in the garden and not leaving the tap running while cleaning teeth.
