Determine the size in litres of the tank that you need.
Work out your
roof catchment area that will be used to fill the rain water tank. Once you
figure out the roof area, use this simple calculation you can
determine how much water you will collect per average annual
rainfall. For every 1mm of rain falling on a 1m2 area
of roof will be approximately .9 Litres.
.9 x Average Rain Fall In mm x Square Meters Of
Eg. .9 x 1200mm x 150 = 162000 Litres per year
Next work out what you will use the
water tank water for e.g. flushing toilets, washing machine, and garden
taps etc. You then can use the following table to calculate your
daily rainwater demand.
- One flush of a dual flush
toilet = 9Litres
- One load in a standard
washing machine = 150Litres
- Washing of an average size
car = 200Litres
- Hosing of a
driveway = 100Litres
- Standard garden
sprinkler = 1000Litres/Hr
- Drip style
sprinkler = 4Litres/Hr
E.g. The tank water is going to be used
to flush two toilets (at an average of 12 flushes each a day) and
one load of washing per day. Add to these washing two cars once a
week and a drip sprinkler ran for 2 hours twice a week. In one week
the demand would be 2,678 Litres.
STEP 2: Determine
where you want to locate the tank.
Find the most
appropriate area in your yard for the water tank. Take into account that
you need to run a downpipe to fill the tank, it’s not going to
impeded access down the side of the house and local council
guidelines. Now measure the designated area that you want to situate
your rainwater tank.
Calculate which water tank is best for you.
Using all your
previous measurements and calculations you can now decide on a tank
from our extensive range which is best suited to your needs.
E.g. You have a space
down the side of your house that is 1200mm wide and 5000mm long with
a space 3000mm to your eaves. You could fit a 5000Litre slimline
tank that is 825mm wide x 4075mm long x 2180 high. This would give
you approximately one and a half weeks of rainwater to use if the
rainwater tank was full.
If you are using
the tank water for toilet flushing etc, a Davey Rain Bank Switch is
recommended. This will automatically switch over to mains water
supply for flushing of the toilets and washing machine when the tank
level drops too low. If the tank water is only going to be used to
water the garden and wash cars etc a standard pump can be used.