The hosepipes go off in Kent on Friday. The machines that never sleep want the same water.

From 3 July, South East Water bars hosepipes and sprinklers for around 850,000 customers across Kent and Sussex — announced last week at the very peak of the heat. The heat itself has gone: it broke at the weekend, after a provisional 37.3°C at Santon Downham on 27 June made it the hottest June day Britain has recorded. But the water stress the heat exposed does not leave with the temperature, and that is the part worth understanding.

Here is the mechanism that matters, because it is the one most people get wrong. A data centre is a hall of machines that turn electricity into heat, and that heat has to go somewhere; one common way to move it is to evaporate water, the same physics as sweat. The fear that follows — that data centres are quietly draining Britain's reservoirs — is, today, largely untrue here. A survey of English sites by the trade body techUK and the Environment Agency found that around half use cooling systems that need little or no mains water, and that the great majority use under 10,000 cubic metres a year. On water, Britain is not California.

The honest worry is not the annual total. It is the timing, and the map. Cooling demand spikes on exactly the hottest, driest days — the days households also use the most water and rivers run lowest — so the strain shows up as a coincidence of peaks, not an average. And the next wave of building is heading for the wrong places: by one count, 84% of proposed UK data centres are sited in water-stressed areas, clustered around London and the south-east, the very regions the Environment Agency is warning could face drought this year. Because the government has classed data centres as Critical National Infrastructure, water companies have less room to turn them away.

So hold both halves, as this desk always tries to. The data centre is not a villain stealing the gardener's hose; it is a planning choice, made building by building, about where to put a machine that runs without us. The discomfort is in the picture as a whole: the infrastructure of the automated economy is being sited in the driest part of the country at the precise moment its households are being told to stop watering the lawn. That is not weather. It is a decision, and it is being made now.

Why it matters here: If you're in the south-east, the hosepipe ban is the visible edge of a tighter squeeze coming: the same summers that ration your tap are when the AI build-out wants water most, in the same stretched regions. How that's planned — who gets the water on the worst day — is a question for now, not 2030.