The Rising Groundwater Problem

Generally insurance policies in Britain do not cover flood caused by rising groundwater. In practice, loss adjusters will not refuse such a claim, however, if it occurs during a general flood event, when pressure from rising groundwater has been known to burst through concrete floors with explosive force. This can happen if the property is protected by a nearby flood defence and the flood level is higher than the ground floor of the property. The reason for the exclusion dates back to Young v Sun Alliance (1976) which held that flood does not include seepage of water from an underground watercourse. To make matters clear, both personal and commercial property policies now usually specifically exclude rising groundwater.

Nevertheless, insurers should not ignore the problem, because rising groundwater is becoming a serious issue in some areas, particularly London and Liverpool . It is beginning to threaten the foundations of tall buildings, (including insurance company offices), telephone cables and other utilities, and the London Underground, which is already pumping large amounts of water out of its deeper tunnels. The reason that groundwater is rising is that in the past, there used to be large amounts of groundwater extraction by industry in large cities - for example for the brewing and paper industry. This has now stopped, and since the 1960s the groundwater has been inexorably returning to its natural levels.

In 1992, London Underground set up a group to examine the problem of rising groundwater in London . The group is called the General Aquifer, Research, Development and Investigation Team ( "GARDIT" ). The team includes representatives from:

•  Thames Water utilities

•  Environment Agency

•  London Underground

•  Corporation of London

•  Metropolitan Water Company

•  British Property Federation

•  Association of British Insurers

•  British Telecom

Plus Professor J.A. Barker from University College London .

This produced a submission to the Deputy Prime Minister who instigated a 5 year combined Pumping Strategy for London being project managed by Thames Water Utilities. In March 1999 they launched their strategy to solve the problem . In a £30m programme, existing boreholes have been brought back into use and new ones created. Groundwater from three locations in Islington is being pumped into a reservoir in Hackney, where the plan is to treat it if possible and put it into the water supply.

In the future, rising groundwater may be a problem in other areas, due to the increasing use of sustainable drainage systems ("SUDS"). With SUDS, increasing amounts of rainwater will be allowed to soak away into the ground rather than going into rivers or drains. Already some fears have been expressed that small rivers may be starved of water, with effects on wildlife.


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