Report No DWI0419

Feb 1993

The Department for Education (DFE) placed a contract with WRc to undertake a project on water management in schools including water economy measures, health-related aspects of drinking water quality and design calculations for cold water storage tanks. This report covers health-related issues and storage tank design; water economy measures have been identified separately in a draft leaflet aimed at headteachers and governors.

The objectives of the work described in this report were (i) to survey lead levels in school drinking water, recommend a strategy for reducing lead levels and estimate the associated cost; (ii) to assess and report on any other health-related aspects of school drinking water; and (iii) to provide guidance on cold water storage in schools.

There are a number of health-related issues regarding drinking water in schools. Lead in school drinking water is of particular concern because prolonged exposure to relatively low levels has been reported to cause potentially harmful effects, including behavioural changes in children. Lead is virtually absent from water entering supply but contamination by lead arises from lead pipework and lead-containing water fittings. To assess lead levels in school drinking water and the scale of any problem on a national basis, lead concentrations were determined in water samples taken from a representative selection of schools (four schools in each of five local authority areas). At the same time as undertaking such sampling, the water supply system was surveyed and any other health-related aspects of school drinking water (e.g. risks from Legionella) were appraised.

It was found that water lead levels were likely to breach the statutory maximum (50 µg/l) in schools with lead pipework. However, it should be noted that the proportion of such schools is not very high. The most effective long term strategy for reducing water lead levels is replacement of lead pipework, although flushing water before drinking and installation of water filters for lead removal could be effective short-term measures. Remedial action should be targeted first at older schools (pre 1950s) where lead pipework is more likely to be present and nursery, infant and primary schools should take priority over secondary schools because of the potentially greater danger of lead to younger children. The cost of replacing the lead pipework in a school is estimated at about £400 for the supply pipe and £600-2000 for internal plumbing; replacement of the communication pipe for which the water company is responsible would cost £250-400.

A small proportion of schools have plumbing arrangements that could allow Legionella to proliferate, although schoolchildren would be at low risk of contracting Legionellosis. The general strategy for dealing with this organism is to keep cold water cold and hot water hot, and to avoid lukewarm conditions in which the micro-organism thrives. Pipework carrying mixed hot and cold water (e.g. to showers) should be kept to a minimum. The condition of tanks storing water for potable use is an area of concern, and a programme of inspection, renovation and maintenance should be given priority. Fittings and appliances connected to drinking water mains should be fitted with anti-backflow devices to prevent contaminated water siphoning back into the system.

A further aspect of water supplies in schools is the size of cold water storage tanks. Currently accepted professional guidance results in a requirement for very large storage tanks and consequential high building costs. Thus a review of storage tank de sign was undertaken. Current practice is based on a historical requirement for provision of one day's supply of water within a building. In the great majority of water supply areas this requirement no longer applies and it is more appropriate to allocate cold water storage on the basis of anticipated maximum demand for water and/or number of water fittings.

Copies of this report may be available as an Acrobat pdf download under the 'Find Completed Research' heading on the DWI website.