NEW RESERVOIRS, water treatment plant upgrades and increased sewerage capacity are all vital if Britain is to avoid the worst effects of climate change, the Institution told a Parliamentary Committee last week.
Much better use of expensively processed wastewater, particularly from newly upgraded foul water treatment works in coastal towns and cities, should be examined too, the ICE told MPs.
Water should be recycled to river catchments rather than being discharged into the sea.
And use of desalination for water production should be considered.
The Commons Environment, Food & Rural Affairs Committee heard evidence from ICE water board chairman Graham Setterfield and water board member Chris Binnie.
Their evidence was underlined by freakish 'monsoon' rainstorms over London. They said reluctance to build new water reservoirs must be reexamined, to increase capacity for drought storage. Reservoirs could also help with flow control during periods of high flood risk.
'For the last 10 years the Environment Agency has resisted plans for new reservoir development, although at the end of 2003 the Agency's chief executive signalled a change in attitude, ' said the Institution's written evidence to the committee.
'There is a period from 1985 to 2020 when no new public water supply reservoirs entered or will enter service.'
The ICE is worried about changing rainfall patterns. The problem is not that overall rainfall levels will drop or that there is essentially a shortage of water.
Only some 10% of the country's annual river flow volume is used for supply and this is unlikely to rise to more than 15% as population and demand increases But regional and seasonal rainfall distribution could change significantly, the Institution warned. The southeast could be particularly affected.
According to the projections used by the Environment Agency, winter rainfall could rise 10% in the next 25 years and summer rainfall could drop 10%. But several factors exaggerate the impact of summer shortfall.
Chris Binnie said that evaporation and plant transpiration increases in higher temperatures. This can mean late summer river flows will drop by up to 34% after 2020.
Abstraction and topping up from single season critical storage reservoirs would be affected.
Demand could also rise as people want to wash more, gardens need more water, and farming irrigation needs increase.
River flows may need to increase rather than decrease because higher temperatures reduce water oxygenation.
There is also a possible detrimental effect on foul water processing which may need more water. Sewer sizes might need to increase.
Environmental concern would almost certainly be amplified by water quality and pollution targets set by the European Union's Water Framework Directive, which will be implemented over the next 10 years.