الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
Now with modern civilization and high building era, most of such buildings are provided with tanks to supply the high flats with constant potable water, in which stored water is used, hence the idea of investigating such water for bacterial contamination. This study was carried out on 200 water samples ( 100 sample & 100 control) collected from repress ntative tanks of five different mrigin of supply ( 20 from each of Bab Shark station, El Syofe, El Maamora, El Manshia and Forn El geraya station ). All water samples and control were examined for pH, residual chlorine, temperature and for the pre sence of faecal coliforms and faecal streptococci by using the MPN method for enumeration The results of this study revealed the following: I J , III 1) Out of the 100 water samples examined, 15 were free from faecal coliforms while 60 were free from faecal streptococci. 2) For control samples, 48 and 98 were free from faecal coliforms and faecal streptococci resp ectively. 3) Water pH ranged from 7.0 - 7.6 in the tested tanks. 4) Temperature ranged from 18 - 31 °c and there was an increase in bacterial counts upon incr easing the temperature. 5) The tested tanks ages ~ere from one year to ~ 40 years, in the old buildings. 6) Frequency of cleaning of tanks were from one month to 3 years or irregularly. 7) Tanks were constructed from 4 different types of materials namely steel plates, fiber glass, . j barrels and reinforced concrete. Steel plates and reinforced concrete showed the least of con tamination while the barrels have the highest percentage. 8) The residual chlorine ( as detected by DPD colorimetric method) in the tanks ranged from ( 0.2 - 0.6 ppm.) There was a decrease of bac terial counts (especially faecal streptococci) with the increase of residual chlorine. 9) Maximum MPN faecal coliforms in water were 270 m.o./ 100 ml of water and were 221 m.o./ 100 ml. for faecal streptococci. la) Most of the tanks were defective with covers.