Streamline - Spring 2014 - (Page 29)
Establishing a Water Distribution
System Flushing Program
THERE ARE MANY reasons why a lot of water systems do not actively pursue a flushing program.
Some of the most common reasons are:
* "We don't have the time or manpower to devote to it."
* "It would be an inefficient use of water."
* "We wouldn't know where to begin."
can maintain a
use of a flushing
a better finished
product to your
The list is essentially endless, but the fact
remains that an efficient flushing program is an
integral part of water distribution system operations and maintenance. Not unlike your vehicle,
your water distribution system requires regularly
scheduled maintenance in order to perform under
Every water treatment plant operator is more
than familiar with system sampling requirements
and their frequency. In addition to an up-todate sampling and analysis program, your water
system should ideally also have an up-to-date
ongoing flushing program as well.
The purpose of a regular flushing program
is to remove or flush out minerals; sediment,
discoloration and other particulate organic matter than can accumulate in the water distribution
lines over the course of time. After all, even
the best water can become stale if not used or
turned over regularly. Your system can maintain
a fresher water supply by implementing the use
of a flushing program, and therefore provide a
better finished product to your customers.
A fresher water supply will allow for the use of
a reduced amount of disinfectant, such as chlorine,
in the water, but still maintain an adequate disinfection amount as required by regulatory agencies.
Just because they carry potable water does not
necessarily mean that the interior of water pipes
are clean. Water mains are designed to carry fire
flow, which usually is several times in volume
more than domestic or commercial flow rates.
As such, during normal residential usage,
the flow velocity through the pipes is normally
fairly low. Because of this, solids may settle out
on the bottom of the pipes, becoming a more
significant problem where there are dead-end
lines not looped into the system or in areas of
Over time, these deposits can reduce the carrying capacity of the pipe and result in complaints
of discoloration and taste/odor problems when
stirred up by increases in flow. A good flushing
program utilizing high velocity will normally
remove most of the settled substances and discolored or stale water.
Preventive maintenance of the water system
will also allow personnel to check, record and
update water pressure and flow rates in order
to ensure the water system is functioning properly and to verify that there is ample water flow
for firefighting suppression. Identification of
hydrants, valves, and other appurtenances in need
of repair or replacement can then be prioritized
and worked into a systematic repair schedule.
To break it down, flushing involves opening
specifically selected fire hydrants and valves under
controlled conditions to scour the inner surface
of the pipe wall. A desired velocity of at least
2.5 feet per second should result in an acceptable
scour effect. The scouring process helps to remove
corrosions, scale, and sediment that accumulate
naturally over time. If otherwise left in place, these
deposits can degrade water quality and restrict
pipeline carrying capacity, resulting in a decrease
of available volume and pressure.
In the time leading up to the beginning of
the flushing program, all water reserves should
be gradually increased in order to compensate
for the demand of water that will be used in the
Table of Contents for the Digital Edition of Streamline - Spring 2014
From the President
From the Executive Director
The Importance of an Immediate Response
What’s New in UV?
Proper Disposal of Pharmacy Products
Source Water Protection Notes
Ergs, Joules and Other Stuff
Establishing a Water Distribution System Flushing Program
Curtis Water Wins Big in D.C.
Throwing My Loop: Friends to Keep You Warm
Do You Know What Your VRWA Benefits Are?
Welcome New Members
Board of Directors
Index to Advertisers/Ad.com
Streamline - Spring 2014