Plumbing Connection 3-2015

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PLUMBING CONNECTION

SPRING 2015

KEEPING YOUR PIPES HEALTHY

healthy plumbing system has to consider everything

from design, installation, and commissioning to the

operation of the system for the entirety of its service

life. Plumbing systems that are poorly designed, or where

the systems operation has changed over time, can lead to

poor quality water.

One of the greatest threats to the quality and longevity of

a plumbing system is stagnant

water. Allowing stagnant water to

develop can generate biofilms in

the pipes, potentially allowing the

growth of pathogens which are

harmful to people. Uncirculated

water can accumulate toxins

from chemical absorbed through

plastic pipes or heavy metals

being leached from metallic pipes

over time.

The Plumbing Code of Australia

and Australian Standard AS /NZS

3500 set out requirements and

guidelines to ensure that these

problems do not arise. For other

useful design ideas and methods,

download the Hydraulic Services

Design Guide from www.copper.

com.au

DESIGN & INSTALLATION

The correct design of

a plumbing system is key

to healthy, high quality

performance. During design, dead

leg piping should be avoided or

restricted to being as short in length as possible. A flushing

facility (tap) should be provided where there is low draw-off

and fixtures that are seldom used should be placed on flow

lines or close to a regularly used service.

Cross-connections of the drinking water supply

to other water supplies, such as

rainwater or recycled water, is another

potential contamination. All water

supply systems must be designed

and installed so as to prevent

contaminants from entering the

drinking water supply.

Where there is a possibility of cross-connection,

protection is achieved by the installation of backflow

prevention devices and air gaps between supply pipework

and storage systems. Identification and marking of non-

potable water supplies and colour coding of pipework is

another way of reducing the chances of contamination.

Section 4 of Australian/New Zealand Standard AS/NZS

3500.1 deals with this aspect and

must be strictly

adhered to.

Correct pipe sizing during

design is also crucial. There

needs to be sufficient water for

all the intended uses, including

peak demand, and if the pipe size

is too small the water velocity

and friction losses will be too

great, potentially causing erosion

and wearing of the pipes. If the

pipes are excessively oversized

however, there will be insufficient

flow to minimise biofilm build up

and settling of silt.

COMMISSIONING & OPERATION

During commissioning all

systems shall be thoroughly

flushed out as soon as possible

after installation to remove

foreign matter and should

continue until the water runs

completely clear. The system can

then be pressure tested to the

relevant regulation.

Water from reticulated systems (municipal water supply)

is usually satisfactory for flushing and testing purposes.

Where non-disinfected water is to be used for flushing

and testing, water shall be disinfected. A procedure for

disinfecting water is outlined in AS 4809 and AS/NZS

3500.1.

If more than 8 weeks between installation and full system

use is unavoidable:

∫ the system shall be kept completely full and clean water

shall be flushed frequently (every 2 weeks) from each

fixture until the system is used;

IT’S ALL A MATTER OF THE RIGHT PRODUCTS, INVESTMENT AND BALANCE SAYS CEO OF THE INTERNATIONAL

COPPER ASSOCIATION AUSTRALIA

JOHN FENNELL.

COPPER CONNECTION

JOHN FENNELL

Hydraulic Services Design Guide

EditionApril 2014