Practical implications of the use of groundwater-protection tools in water-supply risk assessment

The tools of vulnerability mapping and groundwater-protection zoning were developed during the early 1990s to enable the National Rivers Authority and its successor (the Environment Agency) to realise a national ground-water-protection policy for England and Wales. The resultant maps and protection zones cover more than 2250 public water supplies, tapping over 160 aquifers, and took almost five years to prepare. An opportunity for the UK water industry to assess their usefulness arose in 1999 when new Government regulations required water companies to conduct risk assessments for the troublesome parasite Cryptosporidium, and this paper reviews some results of that exercise. In the light of widespread doubts about the effectiveness of sporadic monitoring alone, in protecting the health of users of private ground-water supplies, a simple and pragmatic pollution hazard assessment procedure is suggested, employing combined use of sanitary surveys with an aquifer vulnerability flowchart.