VPE 511: Environment and Environmental Hygiene (2+1)

ODOUR AND TASTE

• Odour and taste can only give an indication of sewage contamination if it is excessive , but they are useful in detecting other unusual types of contamination which are difficult to detect chemically.
• For example, the accidental contamination with small quantities of paraffin oil or similar substances sometimes occurs; chemical methods may not be sufficiently sensitive to detect traces of these compounds, and in such cases taste and smell may be the only guides to the presence of these contaminants.
• Peaty water nearly always has a slight adour. Certain waters contain sulphuretted hydrogen.
• Decomposing aquatic fauna and flora in service mains are not infrequently the cause of “smelly” water.
• Rain water has a flat insipid taste. Soft waters taste “soft”, Ferruginous waters taste of ink. Waters containing much sodium chloride have a brackish taste.
•  The water from newly laid mains may have a tarry flavour.
• Water treated with bleaching powder tastes of chlorine if the available chlorine in the water exceeds three of four parts per million.
•  Hard waters, and also those containing nitrates and carbonic acid, are more palatable than soft waters of those free from gas in solution.