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the vortex filter. The incoming water is directed
round the inside of a vertical cylinder such that
the clean water flows out through a hole in
the side and the leaves fall vertically to drain.
In most conditions, the vortex filter delivers the
highest ratio of clean water to waste.
So how much maintenance is needed to
keep your rainwater clean? It’s nice to know
that you have crystal clear water underground
suitable not just for the toilets and car washing,
but for washing your clothes also (at 50 litres
per wash cycle!).
Regular Check
Well, checking for leaks in something which
is 2 metres below ground is a tough call; but
keep an eye around the top of the tank for
water-logged ground in the rare case that you
have a pipe or tank leak. Checking for stability
Harvesting the Rain
is similar; you will notice pretty quickly if the
tank moves or if there is earth movement or
subsidence around the tank. If so, then you
should get a groundworks contractor to find out
other floats underneath a plastic ball so that the the reason and re-establish a good surround of
Marcus Bicknell, Partner,
water is taken in from the cleanest part of the concrete, shingle or top soil around the tank.
Marketing and Technical,
volume of water, i.e. just below the surface. In The frequency of checking for cleanliness is
the absence of a floating intake, a 1000 watt up to the user. Certainly it is important in the
Rainwaterharvesting
3500 litre per hour high debit pump is likely to months after installation to make sure the filter
suck in debris from near the floor of the tank. and pump are working well; you can see this by
rainwater harvesting system once the colour of the water in your toilets. At the first
A
installed produces clean rainwater Basket Filter autumn, if your house roof is subject to falling
by several natural processes. It is There are three basic types, one of which leaves, lift the manhole cover of the tank, lift the
however important to consider the belongs to a by-gone age: the basket filter. lid of the self cleaning leaf filter and check that
maintenance of the system to Imagine having to get on hands and knees in there is no blockage. You can be pretty certain,
ensure a clean rain machine. Throughout the the garden every few days (in autumn) or weeks, if the autumn leaves do not sit in the filter, that
following article one specialist company explains lifting a manhole cover to empty the basket of you have a good installation with good water
the various parts of a rainwater system and leaves. Not very appetsing. Think also of the through-flow. You could probably then reduce
advises on how to keep them clean. fact that a basket filter is acting like a tea your filter inspection to once a year. If on the
strainer: the leaves are sitting in this big strainer other hand you have leaves in the filter then the
Leaf Filters while they start decaying and new water is inlet pipe or outlet pipe approach angle is
Firstly, the leaf filter, which separates leaves flushed through them, carrying small particles insufficient or the soakaway has not been dug
and debris from the water to be stored. I’ll come and impurities with them. big enough. Bear these words in mind before
back to different types of filter. you build your rainwater system, not afterwards.
Through-Flow Filter
Calming Device The through-flow self-cleaning filter is much For the rest of your system indoors, treat it
Secondly, the vertical pipe in the tank from better and, for homes with rainwater tanks, the like any other part of the plumbing. In practice
the filter to the base of the tank must have a most popular. The principle is that the flow of you will only have to intervene when something
calming device where it meets the floor of the water over a near-horizontal mesh filter pushes goes wrong.
tank. Some silt settles to the floor of the tank the debris out to
(as in nature, in an underground pool) so it is the drain or
important that the incoming flow of water does soakaway while
not disturb the silt. The calming device simply the clean water
directs the water flow, after the filter, away from drops through
the floor of the tank itself. the mesh to the
tank. In this way,
Siphon the new water is
Thirdly, a good U-tube siphon at the high not flowing
water level of the tank acts both as a rodent through the
guard and as a surface dirt removal system. leaves: they have
As the water comes up to high level, the siphon been pushed
effect sucks a good amount of water off the top away already.
of the volume and takes floating debris with it.
Vortex Filter
Pump The third
Fourthly, the pump, which in most systems is type of filter,
submerged in the bottom of the underground used on homes
storage tank, must have a floating intake. The and bigger
pipe connects to the intake of the pump and its installations, is
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