HC Deb 21 February 1978 vol 944 cc609-10W
Mr. Skeet

asked the Secretary of State for Social Services what is the quantity of nitrates in water in East Anglia; and how this compares with internationally accepted standards.

Mr. Marks

The World Health Organisation's European Standards for nitrate in drinking water are:—recommended level—less than 50 mg./litre; acceptable level—50 to 100 mg./litre; not recommended—over 100 mg./litre.

For most sources in East Anglia the nitrate concentration is normally under 50 mg./litre. A number of borehole water sources, particularly in Cambridgeshire, Lincolnshire, Norfolk and South Humberside, deriving water from the Lincolnshire limestone or chalk aquifers, and exceptionally one small surface source, contain nitrate concentrations which regularly exceed 50 mg./litre during part of the year. No water in supply has exceeded the WHO acceptable limit of 100 mg./litre.

Mr. Skeet

asked the Secretary of State for Social Services why nitrate or nitrate concentrations in water are more pronounced in East Anglia than in other parts of the United Kingdom; whether there is continuous monitoring of the chemicals; and what steps are taken to safeguard health in the region.

Mr. Marks

No water in supply in East Anglia exceeds the WHO acceptable limit of 100 mg. of nitrate per litre. Many factors contribute to the occurrence of relatively high nitrate concentrations in some sources. They include low annual rainfall, the degree of mineralisation of organically-bound nitrogen in soil and animal manures, land usage patterns, the leaching of artificial fertilizers and the natural geology of the catchments. All sources of potable water likely to show high nitrate concentrations are monitored regularly at frequent intervals. Where the highest concentrations occur, measures are being taken to introduce specific water treatment processes to reduce the nitrate content. It is normal practice for water authorities to keep health authorities informed of nitrate levels.

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