FEATURE
49
backup water system for drinking purposes, extreme care needs
to be taken to install the correct filtration and water purification
system as supplied by reputable suppliers.
“Your first step, after determining the client’s needs, is a site
visit. Your research on site will enable you to draw up a rational
design. Depending on the design, you will be able to determine
how much pipework and fittings are required, the number of
tanks, new gutters and downpipes, booster pumps, leaf catchers,
and rain filters to flush away any leaves, sand particles, small
branches and so on, and whether any water filtration/purification
system will be applied, as well as where the excess overflow
rainwater will run off to once the tanks are full. In commercial and
industrial projects, you might have more than one roof and might
need submersible pumps situated in underground collection
tanks to transfer the water coming from the downpipes to the
main above-ground storage tanks,” says Brainin. This is essential
for the end user, whether residential, industrial, or commercial, as
you can now start with a final design and estimate a cost.
The following should be considered when doing the site visit:
1. Look at the roof space. When measuring the rooftop
area, it is important to measure the roof’s horizontal
projection (as if you were looking straight down on the
roof from above), The square meterage of the roof, times
the average rainfall, divided by the months, will give you
an estimate of the litres of water that you will be able to
harvest each month for the project.
2. Where to position the tanks. Depending on the space available,
for residential, industrial, or commercial rainwater harvesting,
the number of tanks will depend on the litres of water that
can potentially be collected. Ideally, you should look at trying
to capitalise on harvesting as much rainwater as possible, but
this would also be budget dependant and the system should be
designed so that additional tanks can always be added on at
a later stage. Visiting the site will determine the best option for
the positioning of the tanks. How many tanks will be used will
also be determined by your calculations — this can range from
750 litres up to thousands when you look at commercial and
industrial rainwater systems.
Brainin says they are busy with designs that include tens of
thousands of litres of water storage for commercial and industrial
projects. Tanks are now being made in various shapes, sizes,
and colours from various suppliers, making them aesthetically
pleasing, and should also be considered as an essential part of
the design. Sectional steel tanks play just as much of a vital role
in rainwater storage and are more conducive to the commercial
and industrial sectors.
HOW A TYPICAL DESIGN WORKS
For a simple residential rainwater harvesting system, downpipes will
run from your gutters, connected to a leaf catcher prior to entering
the tank. “This offers excellent filtration and is very important before
the water runs into the storage tanks, as not only leaves but bird
droppings are also on the roof and in the gutters and need to be
flushed away, rather than entering the tanks. The downpipes will then
run into your storage tank,” explains Brainin.
June 2018 Volume 24 I Number 4