It is vital for the self-cleaning function of the Optimax filter that water flows into the turret
and out at a firm flow rate. If there is no main drain on site then ensure that the
soakaway conforms to the following, as shown in the picture below:
(6) To drain or
soakaw ay
(3) From ro of
dow npipe
(4) D ebris “out” also acts as
overflow
if Optim ax used
(9) C almed in let (n ot sh ow n)
(2) U nderground
storage tank
(7) Filter
(Optim ax shown here)
(1) Siph on attached to
filter outlet
(8) Filtered
w ater out
1. The last metre of 110mm (4 inch) drainpipe arriving at the filter should have a drop
of 20 to 50 millimetres (2-5%) to accelerate water flow, i.e. twice the gradient
shown in the manufacturer’s instructions .
2. The first metre of drainpipe after the filter should also have a drop of 20 or 50
millimetres to encourage flow away from the filter, whether or not the U-tube siphon
(as a rodent and odour guard) is fitted.
3. If this overflow/debris outlet does not go to main drain the soakaway must be
constructed to high standard and high volume.
4. The soakaway should be of a volume sufficient to ensure that water does
not back up to the filter.
5. Where appropriate, the overflow/debris outlet pipe should be fitted with an anti-
surcharge or anti-backflow device (BS 8515:2009, ¶ 4.9)
6. The soakaway should be at least two metres away from the tank (do not consider that
back fill round the tank could be used as the soakaway).
© 2011 Rainwater Harvesting Ltd - All rights reserved.
Carat with Optimax and Rain Director or Mains Backup
RWH 042
Rain Director
®
and Mains Backup in a Box
®
are registered Trade Marks and may not be used without permission.
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