TECHNICAL
55
Play your part in
looking after our
water resources
Most of us have the luxury of having water on tap
in our homes. Most of us also have the luxury of
this water being fit for human consumption.
By Patrick Gordon | All images by Patrick Gordon
The water services providers go to great lengths to
provide us with water that is termed “Blue Drop”
quality. But what do they expect in return for this?
We are supposed to make sure that we do not waste
this water by letting it just leak out of our plumbing
systems.
So our first responsibility is in not wasting it. Many of us are
also acting responsibly and we thus do rain water harvesting
and we recycle the grey water from our drains. Herein is the
problem; we are not allowed to mix our municipal water with
these alternative water sources. So how do we keep them
separated but also together in our homes?
just put a non-return valve in the line
and then we are safe? The answer
is no.
A non-return valve is only
as good as the condition
of the seat inside. If any
dirt is trapped on the
seat, the valve is rendered
useless as now the water
will be able to leak back.
So what to do?
The correct item to fit in the line is a Reduced
Pressure Zone Backflow Preventer. This has
two non-return valves and a pressure zone
that is kept closed as long as there is pressure
in the system. As soon as the mains pressure
drops away the reduced pressure zone opens
up to the atmosphere.
Now if the downstream non-return valve leaks any water that
enters this chamber, it will spill out to the atmosphere and
will immediately be noticeable and you can take any needed
action. In this way there is absolutely no chance of the
alternative water entering the municipal supply.
Make sure that these alternative waters are not used in the
same lines as potable waters. We need to make sure that
there is backflow prevention on these lines so that none of
this water can flow back into the municipal lines. So can we
August 2019 Volume 25 I Number 6
The municipal supply normally is also at a higher pressure
than the pressure rating of your domestic plumbing system.
This means that we have to make sure that our system is
fitted with a suitable pressure reducing valve.
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