comes from groundwater extracted through its production wells. Because of this, sand, silt
and sediments are pumped along with the water. These substances cling to the walls of the
pipes and tend to accumulate over time.
A COWD personnel opens the blow off valve during a flushing activity.
When there is zero or low pressure, like when isolation has to be carried out to facilitate
interconnection works or leak repairs, the deposited substances remain in the pipe walls.
However, when normal pressure is restored after said activities, these deposits are carried
along with the flow causing the water which comes out from the faucets turbid, even murky
at times. When this happens, COWD advises its customers to allow the water to flow until it
becomes clear.
This is the very reason why COWD conducts flushing after repairs aside from the flushing it
conducts regularly in different parts of its service area. Flushing keeps the entire distribution
system refreshed. Since flushing requires high pressure, it is usually conducted at night when
consumption is least.
Aside from these flushing activities, COWD also conducts regular monitoring of chlorine residual
and bacteriological testing on the water samples collected from COWD production wells and various
sampling points. Once a year, water samples are also sent to an accredited laboratory for physical
and chemical tests. These measures are being undertaken to ensure that the quality of water supplied
is compliant with the standards set by the Philippine National Standards for Drinking Water or PNSDW .