How anguished anglers stop us hosing the roses

A change in the philosophy of water management has led to the current hosepipe ban. Michael Price explains

By the end of this week, hosepipe bans are likely to have been imposed on more than 18 million people, nearly a third of Britain's population, as a result of the worsening drought. According to the meteorologists' definition of drought - at least 15 consecutive days with rainfall less than one-hundredth of an inch, or 0.25mm - most of Britain is certainly experiencing drought. Many areas have had the longest, hottest spell of weather since 1976. But water shortages are not generally caused by dry summers, but by dry winters. From April to September plants are growing most actively, and their growth uses a lot of water; a typical figure for south-east England would be the equivalent of a depth of water of about 100mm per month, or twice the average monthly rainfall. Since all the water cannot come from the rain, it comes from the soil, which dries out. Any rain that does fall during this time, instead of being shed to flow to rivers, or trickling on down through the soil to replenish the aquifers, is absorbed.

So "drought" in summer makes little difference to the amount of water available for us to use. Demand increases through garden watering and spray irrigation but thisusually represents a relatively small proportion of our annual national consumption.

One problem is what water companies call the garden-centre syndrome. This occurs in May, when gardeners rush out to buy plants, shove them in the ground and water them copiously. At that time we may pose a problem to the water companies, not because they are short of water, but because the water-mains cannot cope with carrying all that extra water. The pipes are too narrow to carry enough water quickly enough. This year, the "garden- centre" effect started late and seems to be carrying on.

The first bans on hosepipes and sprinklers were imposed not because of a resources problem (the quantity of water available) but because of distribution problems: in some areas so many people were using hoses and sprinklers that those living on high ground were without water because of the fall in mains pressure. As the dry weather has pushed up demand, some companies - especially those relying on reservoirs - now face a resources problem, and are also imposing hosepipe bans.

In the east, where groundwater is the main supply source, the wet winter brought exceptional replenishment to aquifers, leaving groundwater levels at or near record highs. These levels are falling rapidly, but are not yet a cause for concern. As they fall the flow of a few streams and smaller rivers will be reduced. Partly because of this, and the resultant cries of anguish from anglers, there has been a change in philosophy in the British water establishment.

In the past, the water industry was "demand led". The policy was to meet demand, sinking new boreholes or building new reservoirs and pipelines as necessary. Last year, the National Rivers Authority introduced demand "management". In essence, the NRA is telling water companies that they cannot expect approval to construct new water sources until they show they have done what they can to reduce demand for water and have done all they reasonably can to reduce water wasted from leaking mains.

In the days when water was usually supplied by a local water board, with the cost "lost" in the rates, appeals for less use of water would likely have been heeded. Now that it is supplied by private companies whose charges and profits have been hitting the headlines, appeals seem less effective. Is metering the answer? The NRA and Ofwat tend to believe it is; the water companies are not so sure. True, it would answer the complaints of people living alone, who object to paying as much for their water as a large family in the same size of house. But water is not like electricity, for which much of the production cost comes from the fuel used in its generation. Water does not have to be generated; although there is a unit cost associated with pumping and treating each litre, much of the cost is associated with the provision and maintenance of the system that brings water to each property - and that cost is the same whether the property is occupied by one person or six. So a fair system of charging for water would have a very high standing charge, and a relatively low unit charge. This is unlikely to reduce consumption, since it means in essence that the water becomes proportionally cheaper as more is used. People in large mansions use a lot, and may not be deterred either by the extra cost or by appeals for conservation.

Another problem with metering is that, for properties served by mains sewerage, it forms the basis for the sewage charge as well as the water charge. It is assumed that every litre of water supplied to the property is also taken away as sewage. For most domestic use this is a reasonable assumption, but it falls down when a lot of water is used in the garden. Since that water does not have to be taken away and treated, it means the avid gardener is paying about twice as much for each litre put on the garden as for each litre used for washing up. Large organisations can request a "non-return to sewer" allowance, but that option is unlikely to be available for the Smiths' herbaceous borders. And much of the insistence on use reduction arises from well-off people who want their village streams and fishing rights safeguarded. Why should the rest of us have our demands managed so their demands can be met? If the Labour Party wants a cause to champion, that might be a better one than Frank Dobson's recent crusade against leaking pipes.

Leakage in Britain is high, but is being reduced. Treating and pumping water which then leaks from the mains is a waste of money, but there comes a point where it is more economic to do that than to repair every minor leak. Most water engineers say that point comes when leakage is down to around 10-15 per cent, depending on the area. Britain still has some way to go to achieve that figure, but it is hard to be certain. Ironically, one of the least-stated benefits of water-metering would be that it would help to identify just where the leaks are - and many small leaks may well turn out to be on the customer's side of the water meter. Very often the water that leaks is not "lost": it often forms unintentional recharge to aquifers or supplements low river flows.

Comparisons are now being made with 1976. But 1976 came after a dry winter and the hot dry summer of 1975. This summer has followed an exceptionally wet winter, just as 1975 did. If dry conditions persist into the autumn, as they did in 1975, and are followed by a dry winter, the comparisons will begin to mean something. Then the debate over water may really hot up.

The writer is senior lecturer in Hydrogeology at the University of Reading. His book 'Introducing groundwater' will be published in September by Chapman and Hall.