Abstract
The presence and multiplication of Pseudomonas aeruginosa within some areas of the potable water supply of London was demonstrated by the analysis of the data collected from a thirteen month, bacteriological survey of the distribution system of the Metropolitan Water Division, Thames Water Authority. Construction materials designed for use within plumbing and distribution systems were shown to be capable of supporting the growth of Ps. aeruginosa in laboratory studies using tap water and one material, in particular was found to be responsible for the persistence of Ps. aeruginosa in new mains. The survival and growth of Ps. aeruginosa in tap water in the absence of construction materials was limited and it was clear that Ps. aeruginosa was not a normal component of the bacterial flora of treated water. The isolation of Ps. aeruginosa from potable water was not considered to be indicative of faecal pollution because it was unrelated to the presence of traditional faecal indicator bacteria - Escherichia coli and coliform bacteria. The multiplication of Ps. aeruginosa within the distribution system was another limiting factor in the use of this organism as an indicator of faecal pollution. It was proposed that Ps. aeruginosa would be suitable as an indicator of the presence in distribution and plumbing systems of construction materials that are unsuitable for use in contact with potable water by virtue of their ability to bring about a noticeable deterioration in the bacteriological, chemical or physical quality of treated water. The spread of Ps. aeruginosa by water has encouraged its appearance as a significant pathogen of man, animals and plants and a notable spoilage organism in industrial premises and commercial products. A clinical study of the potential health hazards associated with the presence of Ps. aeruginosa in potable water and water used for industrial processes was strongly recommended.