| ODOUR AND TASTE Odour and taste assessments are both qualitative and quantitative. Water can acquire taste and odour from a variety of sources of which only a few are of truly natural origin. Soil and rock may contribute off tastes and odours. Sub soil gases and leached out salts can also influence the taste and odour. Industrial and agricultural effluents can also impart taste and odour. Algae, bacteria and actinomycetes can produce taste and odours in water. Geosmin and methylisoborneol are detectable at ng/l concentrations and are resistant to oxidation by chlorination. For the customer it is the ultimate assessment of the product the household provide. If they don't like it they may reject it, ignore it or complain about it. Taste and odour perception is a subjective assessment in the field. The perception of taste and odour varies with the individual and will vary for any given individual over time. Perception can be effected by their eating, drinking and smoking habits. There is also a genetic element which underlies a persons ability to perceive taste and odour. Health implications It is commonly believed that "pure" water has no taste and odour and it is a strongly held belief. Whilst odourless and tasteless water does not guarantee purity of water, impaired taste often coincides with the presence of potentially toxic compounds. Although no health implications can be related directly to taste and odour, these are often very important factors as an alert to potential health related problems. Taste and odour very are useful diagnostic tools in assessing problems. IMPORTANT - WHEN SAMPLING ILLNESS COMPLAINTS - DO NOT TASTE THE WATER ! Unusual tastes and odours must be investigated. The intensity of the taste and odour should always be considered before committing resources. Taste and odours which fall outside the commonly found ones may be the result of contamination of sources or at a localized point in distribution. If a sample contravenes the alert i.e. is detectable and is regarded by the person taking the sample as unsatisfactory for taste or odour on site because of the intensity, a further sample for quantitative analysis should be taken. An semi-quantitative assessment of the intensity of the taste and odour should also be made by the sampler. A list of common complaints and potential causes follows. It is not exhaustive and it must be used with careful judgement with evidence from the site of the problem to be of value. Many other causes are possible. Chlorinous Chlorinous tastes and odours may be the result of chlorination problems at the works. These must be investigated to see if there have been any problems at the works. They may also be due to local mains work in the area, in these cases the distribution manager should be contacted. Taste samples from points upstream and down of the failed point should be investigated. If the problem can be isolated to a customer's tap they should be advised that there is a problem and the precautions they can take to alleviate it. Earthy, musty mouldy and "off" Earthy, musty, mouldy and "off" are commonly identified. These may often be associated with fungal or Pseudomonas aeruginosa growth in fittings prone to warming or which may also have unsuitable materials for relaying potable water within them. (see temperature above "Bad eggs" e.g., Bad eggs - suspect pipework underground is leaking. "TCP taste" Any chlorophenoilc tastes may be attributable to the action of residual chlorine on unsuitable materials e.g., fittings (which are not listed in the Water Research Centre's Directory of Water Fittings and Materials) such as antisplash fittings, washers and sealing gaskets of kettles. Hydrocarbon fuels |