[Bacterial regrowth in drinking water. IV. Bacterial flora in fresh and stagnant water in drinking water purification and in the drinking water distribution system].

Six dead end water pipes were installed inside a Zurich drinking water plant and five others over a distance of 12 km along the distribution system and the water was left stagnating in there for 2 weeks. A total of 1508 bacteria from fresh and stagnating water were isolated and identified. Of these, 241 bacterial isolates from the distribution system were examined using the nutrient-tolerance test, i.

[Bacterial regrowth in drinking water. III. Reasons for regrowth with oligocarbotolerant bacteria].

Investigations have been undertaken into the bacterial regrowth in a Zurich drinking water plant and over a distance of 12 km along the drinking water distribution system. This required installation of eleven chromium steel dead-end water pipes. Counts of oligocarbotolerant bacteria were carried out in 7 or 8 repetitions in fresh water and water left to stagnate for 7 and 14 days respectively (7,8).

[Bacterial regrowth in drinking water. II. Drinking water distribution systems].

Five chromium steel dead-end water pipes were installed over a distance of 12 km along the Zurich city drinking water distribution system. Cell counts were determined in two series of four samplings in fresh water and stagnating water using three different methods. The colony counts of oligocarbon tolerant bacteria (1:10 diluted plate count agar, 20 degrees C, 14 d) in the fresh water was increasing along the distribution line.

[Bacterial regrowth in drinking water. I. The upgrading of drinking water].

Seven dead-end water pipes were installed after each treatment step in a drinking water plant. During a period of 7 weeks the bacterial load of freshwater and stagnating water was investigated with different methods. A modified surface spread plate count (Plate Count Agar, 10-fold diluted, 14 days incubation at 20 degrees C) proved to be more effective than the traditional pour plate method, because it gave consistently higher colony counts and had a lower level of detection (0.