A VALUABLE source of water for drought-stricken parts of the UK is being poisoned by careless local authorities and road maintenance contractors, a leading academic warned this week.
Speaking at the Water Environment 98 conference, head of Middlesex University's Urban Pollution Research Centre professor Bryan Ellis claimed that more than 200M.m3 of water could be 'harvested' from roads in south east England each year.
But he warned: 'We have particular concerns in relation to the use of herbicides on hard surfaces. These chemicals are extremely mobile and nobody really knows their long term health effects.'
Ellis has been investigating the use of surface water run-off from urban areas to recharge depleted aquifers. A similar policy is already in use in the Netherlands, Sweden and the US.
But he concluded: 'We are still far away in terms of predicting how pollutants get into groundwater and how they can be removed. Until this situation changes we are left with the problem of deciding whether these types of facilities should be used or not.'
Ellis claimed that the use of herbicides on roads and railways had increased over the last five years as it is a cost effective weed control. Although this represents only 2% to 3% of the total herbicide application in the UK, water companies are regularly failing European Union drinking water standards because of run-off from hard surfaces, he said.
However, water companies are still keen to use the resource. Anglian Water water resources manager Ed Smith said that despite herbicides from roads accounting for almost half of its EU standard failures in 1994, the company would still consider harvesting surface water.
'As urbanisation takes place, less water is getting into the ground and it is becoming a wasted resource. There is always a risk of getting some contamination, but on the other hand we have to balance the quantity to quality aspect.'
A spokesman for the Highways Agency said every effort was made to obey legislation governing herbicide use. 'Our agents are expected to follow the guidelines and we are not aware of any increased use of herbicides.'