THE DETERMINATION OF TASTE AND ODOUR IN DRINKING WATER IN RELATION TO WATER QUALITY REGULATIONS
Report No FR0254

R I Crane

Dec 1991

SUMMARY

I OBJECTIVES

To review the methods of analysis for the assessment of taste and odour with respect to UK Regulations concerning the quality of drinking water and to recommend laboratory studies to develop reliable procedures.

II REASONS

The assessment of drinking water for odour and taste is one of the more basic tests carried out by water undertakers and it is one of the few water quality assessments that consumers can readily carry out themselves. The Water Supply (Water Quality) Regulations 1989 (and their Scottish equivalents) have set mandatory standards for odour and taste in drinking water. Such standards for what is a subjective assessment lead to many methodological and interpretational problems. The methodology available and associated problems need to be reviewed in order that more reliable techniques can be identified and developed.

III CONCLUSIONS

The taste and odour standards in the EC Directive do not reflect that the determinations required are very subjective and the results will have considerable uncertainty attached to them. None of the currently-used methods are likely to produce results with the UK target precision of +/-1 dilution number.

The meaning of the numbers specified in the Directive appears to have been interpreted differently in the UK and some other Member States. The UK has introduced a scale which appears to be one point more lenient than used elsewhere. However, any real differences would probably be masked by the inherent lack of precision of the analytical methods.

Odour and taste are not precisely definable entities and any numerical value obtained is very dependent on the method used. Therefore in order to produce results comparable between different water undertakers a standard method must be used. At present a variety of methods are used in the UK and Europe and there would probably be differences in the results produced by these methods. A CEN task group is attempting to produce a harmonised (standard) method for the assessment of taste and odour in drinking water. This CEN method could become the standard method for all in the future in relation to testing compliance with the EC Drinking Water Directive and national regulations.

More specific conclusions related to the methodology of taste and odour compliance testing are given. In addition other conclusions on the assessment of taste and odour in drinking water are drawn which are not directly related to compliance with regulations.

IV RECOMMENDATIONS

V RESUME

The report outlines the regulations that cover the assessment of taste and odour in drinking water, discusses the underlying principles of such assessments and describes the various approaches used in the UK, Europe and elsewhere. The review is based on available literature and discussion with laboratories carrying out such assessments in the UK and Europe.

Copies of the Report are available from FWR, price 35.00 less 20% to FWR Members