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Rainwater Harvesting

Rainwater harvesting is the collection and storage of rainwater for reuse on-site, rather than allowing it to run off. These stored waters are used for various purposes such as gardening, irrigation etc. Various methods of rainwater harvesting are described in this section. It is a system of catching rainwater where it falls. In rooftop harvesting, the roof becomes the catchments, and the rainwater is collected from the roof of the house/building. It can be stored in a tank and then pumped to your household or used for irrigation of your garden. The system mainly consists of the following components:

  • 1. Catchment area (roof or structure)
  • 2. Transportation ( pipes and gutters to get the water to the tank)
  • 3. First flush (optional but recommended)
  • 4. Filter (very important to stop contamination of the tank)
1. Catchment area (Roof or Structure)
The surface that receives rainfall directly is the catchment of rainwater harvesting system. It may be terrace, courtyard, or paved or unpaved open ground. Therefore the catchment is the area, which actually contributes rainwater to the harvesting system.
2. Transportation
Rainwater from rooftop should be carried through down pipes to storage/harvesting system. Water pipes should be UV resistant PVC pipes of required capacity. Water from sloping roofs could be caught through gutters and downpipe.
3. First Flush (optional)
First flush is a device used to flush off the water received in first shower. The first shower of rains needs to be flushed-off to avoid contaminating storable/water tank by the probable contaminants of the atmosphere and the catchment roof. It will also help in cleaning of silt and other material deposited on roof during dry seasons Provisions of first rain separator should be made at outlet of each drainpipe.
4. PVC –Pipe filter
There are two types of Filters we install:

This is placed inline on the pipe system from the existing downpipe to the pipe leading to tank or catchment device.

It is normally wall mounted with a stainless steel sieve that can easily be cleaned of all the debris and leaves that get caught in the roof gutters. It prevents contamination of the tank.

This device can be placed in the tank and is round in shape with a stainless steel mesh, with the downpipe discharging on top of it. It captures all the debris and leaves that get caught on the roof which could potentially enter the tank. This type of filter is a bit more difficult to clean.

 

Rain water is collected from the roof of the building is diverted to a storage tank. The storage tank has to be designed according to the water requirements, rainfall and catchment availability. Each drainpipe should ideally (optional) have a first flush device followed by filtration system before connecting to the storage tank. It is advisable that each tank should have excess water over flow system.

 

Excess water could be diverted to recharge system, secondary storage facility or straight to waste. Water from storage tank can be used for many purposes such as:

  • washing and gardening
  • drinking water ( if treated correctly)
  • Piped to the home for toilets

5. Booster Pump
A booster pump can also be fitted to your tank as an optional extra. This is normally done to supply water to the home where water pressure is required or if your tank is below the point of where you wish to supply the water too. It is very convenient if you wish to water your garden with a hose. The price of these units ranges from about R3500 upwards depending on the requirements, brand and power needed.
6. Tank support

All tanks must be placed on a suitable support structure as it’s important to note that once the tank is full of water it weights more than 5 tons if the tank is a 5000l hence if there is no support the tank could potentially collapse.


If the client has suitable paving available then its great, alternatively we can also have custom cast 80mm reinforces slabs delivered for the tank to be placed on. All that is required is a clear area of ground that is level and we do the rest.

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