Planning a rainwater harvesting system: hardware & water tanks

Rainwater harvesting systems range for simple rain barrels to sophisticated systems that integrate with the existing water supply.  Probably the main/most important piece of hardware is the water tank for storing the rainwater but there are a number of other items that must be considered too.

Corrugated iron or ‘tin’ rooftops are ideal rainwater collection surfaces followed by various tiled rooftops.  Thatched roofs are unsuitable for rainwater harvesting.  The building will need to have gutters installed if these are not present already.  A building that has gutters is a significant advantage with regards to cost and time.

The next step is to obtain suitably sized downpipes to attach to the gutters so that the rainwater can be directed to the rainwater tank or rain barrel.  Another piece of hardware that can be fitted is a ‘leaf eater’ mechanism – basically a device that allows leaves and other coarse debris to be diverted away from the downpipe and onto the ground.  There are many designs but most consist of an angled piece of wire mesh within a box.

A ‘first flush’ device is also a useful addition – this ensures that dirty or contaminated rainwater (from dusty rooftops and gutters) is diverted away from the water collection tank.  Again, there are a number of simple designs available.

A low water tank stand may be a requirement in some instances – the water tank should always be installed on a level, strong surface such as a steel water tank platform or concrete base (remember a 5000 litre water tank will exert 5 tonnes of downward pressure!).  Depending on the complexity of the rainwater system and the intended use of the rainwater, other plumbing hardware will be required.

If the rainwater tank is to be manually emptied and the rainwater used for garden irrigation, all that is required is a tap or faucet installed near to the bottom of the water tank.  A hosepipe can be attached to the tap and gravity employed to provide some pressure if the garden/lawn to be watered is at a lower level than the water tank.

If a more complex rainwater system is installed and the rainwater is to be used for drinking, then a filtration/purification system is a must.  UV-filters or other types of water filters can be installed at the point where the rainwater exits the water tank.  It may also be necessary to have a coarser pre-filter installed too.

Integrated rainwater systems will need to have a booster pump installed to provide sufficient pressure.  Other plumbing and hardware includes float switches, extra pipes and fittings and sometimes an electrical control box – these items are best supplied and installed by a professional rainwater system installer or plumber.

It is important to select the right type and size of water tanks, depending on your roof surface area and local rainfall patterns.  The quality of the water tank is important too – if the rainwater is to be for potable purposes, the water tank should be made of food-grade materials and certified to store drinking water.

In South Africa we recommend JoJo Tanks products; all JoJo vertical water tanks and horizontal water tanks are made from food-grade polyethylene and have an FDA-approved black inner lining that inhibits algae growth and helps keep the stored water fresh.  Click on the links below to view the wide range of JoJo Tanks products available in South Africa.

JoJo Tanks South Africa offer a wide range of products such as plastic water tanks and chemical tanks to suit every household, business or agricultural need, including silo tanks and silo tank stands as well as other high quality JoJo Tanks products.  See JoJo Tanks’ VERTICAL TANKS, HORIZONTAL TANKS (transporter tanks), STEEL TANK STANDS and OTHER JOJO PRODUCTS and see JoJo Tanks’ NEW 6000 LITRE UNDERGROUND TANKS. Also see our FAQ and WATER TANK PRICES.