Rain water harvesting – Part 2

In Part I we covered the small rain water tank near the front of the house that will be used for basic garden water, washing the car, and other general water usage.

In this post we will cover the main water tank in the back of the garden that will be used for gardening, filling the pool, water feature, toilets, washing machine (eventually), and the outdoor rain water shower. The rain water will not be used for bathing and drinking water inside the house, as rain water is generally not ideal for daily human consumption, particularly in polluted urban areas, as it contains contaminants for the atmosphere as well as contaminants and bacteria from the roof and gutters etc. We will be filtering the water to try and get  it as clean as possible.

The picture below shows the first steps in laying the water pipes from the water tank to the main house and other areas of the garden. All this had to be done first as trenches needed to be dug and pipes laid underground.

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Next the rain water shower was installed. The decking for the shower was installed using left over wood from the removed roof rafters from the main house and decking planks from then main deck. A large hole was dug under the shower for natural water draining. The hole was dug a lot deeper after the picture was taken, and filled with rocks and stones to allow for bacteria to grow and to reduce any smells caused from the draining water. We will be using environmentally friendly soaps etc for this shower.

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Below in the the finished decking with the tank and shower. Hot water is obtained by using a small gas geyser. Water pressure is provider by a pressure pump which is installed behind the tank.

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The picture below shows the rain water “leaf eater” and first flush diverter. Basically, before the water goes into the tank, it needs to be cleaned as much as possible. The “leaf eater” is the metal sieve which sits its a 45 degree angle, that effectively prevents large pieces of debris and leaves from entering the tank. The 45 degree angle allows the leaves and debris to easily fall off and not block the water flow. The first flush diverter (the thick vertical pipe) basically collects the first few litres of rain water, which is generally the dirtiest as it contains most of the dust and dirt and contaminants. Once this pipe fills up, the rest of the water, which by now should be a lot cleaner, passes into the tank. The first flush diverter then slowly drains out from a small drainage hole at bottom, so that its empty for the next rain. More information on this particular leaf eater and first flush diverter, as well as purchasing information, can be found here.

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Next the concrete slabs were laid for the water feature. The water feature will not only be a garden feature, but will also be a rain water filtration system to filter the and clean the rain water using predominantly water plants.

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Then the water features were built. The water feature consist of 4 “pools” that will flow into each other. The top pool will be fed from the water tank. The water will then flow into the other tanks.

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The picture below shows the final catchment pool. Once the water reached this pool it will then be pumped back up in the main tank.

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The completed water feature shown below. Next the waterproofing needs to be done, and stainless steel water spouts need to be added to allow the water to flow from one pool to another.

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The cost of some of the main components of this rain water harvesting system are as follows:

2500 litre Jojo water tank – About R5000
Leaf Eater and First Pass filter – about R800
Pressure pump – About R2000

The next post will cover the water proofing and hopefully the water feature in action.

Now to patiently wait for the summer rains to get enough water to fill up the tank and pool and water features… may take a little while but we will get there eventually 🙂

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