Rainwater harvesting

When the heavens give you rain, catch it, store it, use it, purify it and even drink it.

Rain harvesting is the best way to catch nature’s precious resource for those dry periods and Controlled Irrigation’s Dan Pillay listed six important points to think about when doing this at home:

1. Size matters

Using average rainfall data for the region and multiplying it by the surface area of the catchment will give the amount of water that may be harvested for the year in litres. Use the average monthly rainfall figure to determine suitable tank storage capacity.

2. Required pressure

A tank placed on the ground provides very little pressure and may not even be sufficient to power a hose pipe. A booster pump may be required and has to be sized according to what the water is used for.

3. Water treatment

Water pH levels differ in different areas and may have a significant impact on domestic pipes and fittings. Analyzing the water and installing appropriate water treatment equipment may extend the life of pipes and fittings.

4. Pre-filter the water

Pre filtration of rain water is essential. Pre-filtration in the form of leaf catchers, tank screens and First Flush greatly reduce the risk of leaves and bird droppings entering the storage tank.

5. Back flow prevention

It is a criminal offense to pollute municipal potable water. The risk of rain harvested water being pumped into the municipal pipe network is highly likely. So sufficient back flow preventing devices must be installed.

6. Underground or on top?

Water storage tanks are designed to withstand internal pressure.

When installing a tank below ground level, it is recommended that you use a special underground tank.

If a normal tank is placed underground, a retaining wall is required to overcome the external pressure created by the surrounding soil, especially when the soil is wet and the tank is empty.

When choosing your water tank, Pillay said the following attributes are important and offered by reputable water tank manufacturers:

“Your tank usually comes with an eight year product guarantee, should be UV resistant with black food grade lining material, which ensures that the water remains safe for human consumption, and should have a black interior to inhibit algae growth. Furthermore it should be chemical resistant where necessary and definitely corrosion and rust resistant,” said Pillay.

 

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