Key Health Data for the West Midlands 2002
CHAPTER THREE: DRINKING WATER QUALITY
List of Tables
List of Figures
Main Body
1: The Geography of the West Midlands
2: Life Expectancy and Inequalities
3: Drinking Water Quality
4: Chemical incidents in the West Midlands
5: Landfill Sites
6: IPPC
7: Fires in the West Midlands
8: Road Traffic Accidents
9: Drownings
10: Access to a healthy diet
11: National Health Service Priority Areas
12: Communicable Disease
13: Older People
3.1 Introduction
Water companies are required to supply wholesome water for domestic or food production purposes and it is a criminal offence for a company to supply water unfit for human consumption (Water Industry Act 1991). UK legislation (Water Supply (Water Quality) Regulations 1989, Water Supply (Water Quality) Regulations 2000) incorporates the standards set out in European Community (EC) Directives (Council Directive 80/778/EEC, Council Directive 98/83/EC) together with additional national standards. Some of the additional standards introduced by the latest Directive will be incorporated in domestic legislation by the end of 2003 (Council Directive 98/83/EC).
Water companies are responsible for monitoring the quality of water supplies and the Secretary of State for Environment, Food and Rural Affairs is responsible for regulating the quality. The latter is carried out by the Drinking Water Inspectorate (DWI) for most of the region and Welsh Water (who supply Herefordshire) is covered by the National Assembly for Wales. The basic unit for monitoring is the water supply zone. This is an area designated by a water company, where there is unlikely to be significant differences in water chemistry and where the population is less than 50,000. There is a defined sampling frequency for each quality parameter depending on the population served in each zone and consumers' taps are used as sampling points. In 2001, over 300,000 samples were analysed in the West Midlands region. All this monitoring information is publicly available and annual reports must be published.
There are three water companies serving the region, which are Severn-Trent Water plc, South Staffordshire Water plc and Dwr Cymru (Welsh Water) (see Figure 3.1 and Table 3.1).
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Figure 3.1. Water companies serving West Midlands 2001. |
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Table 3.1. Water companies serving the region. |
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3.2. Water quality
We have previously reported on lead, pesticides, and polycyclic aromatic hydrocarbons (PAH) levels in the West Midlands (Key Health Data 1998, 1999). This year we are covering lead and PAHs as there were no failures for pesticides in 2001.
3.2.1. Lead
Lead is a general toxicant that accumulates in the skeleton. Infants, children up to six years of age, and pregnant women are most susceptible to its adverse health effects.
Owing to the decreasing use of lead-containing additives in petrol and of lead-containing solder in the food processing industry, concentrations in air and food are declining, and intake from drinking water from the tap now constitutes a greater proportion of the total.
The principal source is dissolution from lead in pipes, solder, fittings, or the service connections to homes. The amount of lead dissolved from the plumbing system depends on several factors, including pH, temperature, water hardness, and standing time of the water. Soft, acidic water is the most plumbosolvent. While lead levels can be reduced by running the tap for some minutes, the only long term solution is likely to be the removal of lead plumbing and fittings. This is potentially disruptive and expensive. The householder is responsible for all pipework to the connection with the water company service pipe, which in most cases means almost to the main in the street. There is concern that the forthcoming reduction of the lead standard from 50 micrograms per litre (µg/l) to 25 micrograms per litre (µg/l) in 2003 and to 10 µg/l by 2013 will mean that even more properties in the region will exceed the standard. This could be a major problem in older supply areas where there are substantial runs of lead pipework.
There are 28 water supply zones exceeding the forthcoming 25 µg/L standard in 2001 are shown in Figure 3.2. A failing zone can refer to individual samples in any 12 month period and does not necessarily mean that all properties with lead pipes in the zone have a problem.
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Figure 3.2. Water supply zones exceeding standards for lead and Poly Aromatic Hydrocarbons. |
3.2.2. Polycyclic Aromatic Hydrocarbons (PAHs)
A large number of polycyclic aromatic hydrocarbons (PAHs) from a variety of combustion and pyrolysis processes have been identified in the environment. In water supplies PAHs are largely derived from coal tar pitch linings of old water mains although coal tar lining has not been used in the Water Industry for over 30 years. There were 25 water supply zones where exceedances were identified in 2001 are shown in figure 3.3.
Little information is available on the oral toxicity of PAHs, especially after long-term exposure. The only PAH for which there are adequate data to base a quantitative risk assessment is benzo(a)pyrene which appears to be a local carcinogen. There are insufficient data available to derive drinking water guidelines for other PAHs and the WHO has made the following recommendations for the PAH group (Key Health Data 1999):
Treatment to achieve the recommended level of turbidity will ensure that PAH levels are reduced to a minimum.
The use of coal-tar based and similar materials for pipe linings and coatings on storage tanks should be discontinued. PAH levels should be monitored regularly in order to determine the background levels against which any changes can be assessed so that remedial action can be taken.
In situations where contamination of drinking water by PAHs has occurred, the specific compounds present and the source of the contamination should be identified, as the carcinogenic potential of PAH compounds varies.
The vast majority of high PAH levels relate to fluoranthene and not benzo(a)pyrene. Fluoranthene will not be a reportable determinant in the new regulations in 2004, being regarded as non-toxic.
3.3. General Quality Assessment of rivers
Despite being landlocked the West Midlands has a considerable network of waterways which are a valuable environmental and recreational resource. The quality of the West Midlands rivers and canals has improved considerably over the years but still requires constant monitoring. This is carried out by the Environment Agency which classifies the water quality of rivers and canals in a General Quality Assessment scheme (GQA). This is designed to provide an accurate and consistent assessment of the state of water quality and changes in this state over time. There are GQAs for aesthetic quality (e.g. litter, odour and colour), biological quality (based on size and sensitivity of macro-invertebrate population) and chemical quality (The Environment Agency). The chemical GQA describes quality in terms of chemical measurements, which detect the most common types of pollution. It assigns one of six grades (A to F) to each stretch of river. The grade is defined by standards for biochemical oxygen demand (BOD), ammonia and dissolved oxygen (see Table 3.2). These are indicators of pollution that apply to all rivers due to the widespread risk of pollution from sewage or farms, the toxicity of ammonia and the requirement for dissolved oxygen for aquatic life.
The routine monitoring programme involves monthly sampling at thousands of locations. Three years worth of data are used to provide robust analyses and the results are made available to the public. (The Environment Agency, 2003).
References
Water Industry Act 1991, Chapter 5 and 6, London: HMSO, 1991.
Water Supply (Water Quality) Regulations (1989), SI 1989/1147, London, 1989.
Water Supply (Water Quality) Regulations (2000), SI 2000/3184, London, 2000.
Council Directive 80/778/EEC relating to the quality of water intended for human consumption, (OJ L 229, 30 August 1980).
Council Directive 98/83/EC on quality of water intended for human consumption, (OJ L 330, 5 December 1998).
Chief Inspector Drinking Water Inspectorate, Drinking Water 2001, (at http://www.dwi.gov.uk/pubs/annrep01/04.htm)
Department of Public Health and Epidemiology Key Health Data for the West Midlands 1998, Birmingham: University of Birmingham, 1998.
Department of Public Health and Epidemiology. Key Health Data for the West Midlands 1999, Birmingham: University of Birmingham, 1999.
WHO International Programme on Chemical Safety Guidelines for Drinking Water Quality, 2nd Edition, Volume 2, Health criteria and other supporting information. Geneva: WHO, 1996.
Environment Agency, 2003 (at http://www.environment-agency.gov.uk/fc)
For more information please contact Sarafina
Cotterill on 0121 414 3368
© Department of Public Health and Epidemiology, University
of Birmingham