1) The country has been scandalised to learn that a fifth of its water disappears in leaks - even during a drought. The truth is worse than that. Ofwat calculated two years ago that if all leaks, including those from consumer pipes, are included, the national water leakage rate may be as high as 33 per cent. But it needn't be so. Both David Walker at Ofwat and Robin Garrett, head of engineering at the Water Services Association, agree that a target of 15 per cent would be achievable and cost-effective for most water companies.
2) Leakage rates have worsened in recent years. North West Water, for example, recently completed a 10-year leak-cutting programme, begun when it was publicly owned, aimed at reducing leaks from 34 per cent to 24 per cent. At the end of the 10 years, the figure was 39 per cent.
3) Plugging leaks is much more cost-effective than the companies claim. According to Garrett, companies only carry out leak-plugging programmes if the cost is less than the value of the water saved, which most companies put at 5-10p per thousand litres. But this is just the cost of treating and pumping the water. Ofwat says the actual cost of providing the disappearing water - including laying pipes, building treatment works and so on - is five times as much, or 25-50p per thousand litres.
4) Companies say a lot of the leaks are from the customers' own pipes. Walker says this is not true. "Most of these leaks will be at the stopcock in the street, which is the water companies' responsibility," he says. When meters were installed on the Isle of Wight five years ago, half of the resulting 20 per cent water saving came from the water company replacing leaky stopcocks when it put the meters in.
5) Few companies actually know how much they lose to leaks. Ofwat believes many companies inadvertently under-report leakage and over-report the amount of water used by their customers. That, says Ofwat, would explain why the East Surrey Water Company says its customers use 25 per cent more water per head than their neighbours, North Surrey.