The statistics from the Institute of Hydrology underline the fact that large parts of Britain's most densely populated region will have hosepipe bans within a few months, unless the weather snaps out of the current pattern.
According to the figures, only six of the past 24 months have had above average rainfall. One of them was this year's very wet February, but it was preceded by an extremely dry January and followed by a March with only a third of the usual rainfall.
This is more unusual than it first sounds. There have been 200 multiplied by 12 such periods of 24 months in the last 200 years, making the dry spell a one in 2,400 event. It really has been very dry Although parts of the North and West still have high rainfall figures, the South and East are getting drier: New York, Rome, Lisbon and Paris, all now get more rain in the average year than London.
The Government's Environment Agency said the flow in half of its 35 "indicator rivers" around England and Wales was below 50 per cent of their averages for this time of year. Levels of groundwater, on which much of the eastern half of England relies for its supplies, are also severely depressed. ''With summer coming up, the window of opportunity for replenishing rivers and groundwater is now very narrow,'' said Terry Marsh of the Institute of Hydrology.
But the three major water companies most likely to be affected by drought, Thames, Anglian, and Southern, all said it was impossible to say if hosepipe bans would be necessary. Thames and Anglian pointed out that they had had no bans for several years. Southern already has a sprinkler ban across West and East Sussex. All three companies said if their regions had near average rainfall from now on into the winter, there should be no more restrictions nor shortages.
Anglian's confidence was highest. ''Unless things get really, really bad I can't see us putting any restrictions in place,'' said a spokeswoman.
The last severe drought was in 1995, with millions of homes affected by hosepipe bans . Things improved in 1996, partly because of a cooler, wetter summer and partly because of a surge of investment by water companies in supply improvements
But will average rainfall resume, or is this a permanent change in precipitation?
Climatologists do not yet know, nor will they for several years. ''If you asked me whether I'd bet on it being climate change, then I would - because that doesn't require me to be scientific,'' said Mr Marsh, who interprets a stream of data from hundreds of river flow meters and rainfall gauges around the country. ''Our climate is inherently capricious, but lately it does seem to have been moving towards the extremes of its range.''
Gardeners and farmers are not the only victims of drought. A recent government study into the impact of a changing climate found that in 1995 subsidence due to clay soils shrinking produced insurance claims totalling pounds 326m.
It may be becoming drier, but Arnold Fulton, chairman of A Fulton Ltd, Umbrella manufacturers in East London, said demand for umbrellas had been increasing ever since he opened his factory. In 1957 it sold three million per year; now it sells 17 m.
''People used to have one good umbrella they took everywhere but now they have two or three,'' said Mr Fulton, who says his company is Britain's biggest manufacturer. ''One in the car, one for carrying about and maybe one at home for going out walking.''
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