PACKAGE : I Bid Document VOLUME : II - Public Health Engineering

After the applicable retention period, the heavily chlorinated water shall be flushed
from the main until the chlorine concentration in the water leaving the mains is no
higher than that generally prevailing in the system or less than 1 mg/l.
After final flushing and before the water main is placed in service, a sample or
samples shall be collected from the end of the line and tested for bacteriological
quality and shall show the absence of coliform organisms. If the initial disinfection
fails to produce satisfactory samples, disinfection shall be repeated until satisfactory
samples have been obtained. When the samples are satisfactory, the main may be
placed in service.
The contractor is expected to carry out the disinfection work as a part of laying the
pipes and his rates for laying the pipes should include the disinfection and other
connected works till the main is placed in service unless otherwise specified in the
schedule.
GTS : General Technical specification. Page 92