Rain water harvesting installation

I am a member of two facebook groups which try to assist people in the Western Cape, as well as the rest of South Africa, with regards to drought solutions - namely Water Shedding SA and Water Shortage South Africa.  I know that most of this will be of interest to South African readers, but, perhaps everyone should be aware of, and will benefit from how to help themselves to become more self-sufficient with regards to their water - and it's storage - especially rain water.  Water is our most precious comodity - more valuable than gold, diamonds, oil or anything else considered precious by mankind.

In those groups I have read so many posts from people asking who can install their rain water tanks. I think the "lack of knowledge" and cost implication (of firstly purchasing the tank, and then the additional cost of getting a company to come and do the installation / gutter link up) may be preventing people from installing a rain water tank. So I thought I would share the simplicity of it.

For those of you are new readers of my blog, here is some background: we live on a 2 Ha smallholding and we have installed 9 X 5 000lt tanks over the past 7 - 8 years.

Our potable water is directed from our mains pipe into the top of
 the potable water storage tank

 As our "mains" water supply is erratic (either Overberg Water has "pump" / Escom power supply problems or farmers accidentally plough up the main line - this happens quite frequently) so we have dedicated one X 5 000 lt tank to potable water. Given the aforementioned causes of possible breaks in our potable water supply, water independence / security is therefore imperative for us - especially in the heat of summer.

Details of water connection from pump to the house, and our
 power source to the pump

Of the remaining 8 X tanks, 3 X tanks are positioned at the end of gutters and collect rainwater and the balance of 5 X tanks are postioned on the higher parts of the land in order to irrigate via gravity and / or pump.

A secure base is vital for a water storage tank

Please ensure that you either position your tank on a (smooth) concrete slab, a square of level pavers, or a good 10cm thick bed of gravel (please ensure that there are NO SHARP GRAVEL POINTS sticking up or they could puncture the tank).

Our tank / pump connection

1 000lt (filled weight is 1 ton), 2000 lt (filled weight is 2 tons) or 5 000lt (filled weight is 5 ton) tanks are heavy when they are full, and when the ground beneath them is wet from (hopefully good 😀👍👍 ) rains, the risk of the tank falling sideways / collapsing is a possibility IF the tank isn't sitting level. This definitely applies to a clay soil - as clay is "volatile" when very wet.

Two pics showing one of the two types of valves we used - in these pictures the image on the left with the handle pointing upwards, the valve is closed and in the image on the right showing the handle lying parallel to the valve, the the valve is open.

When you purchase your tank(s) ask the supplier for the specific water tank fitting requirements. Then, either get them to supply those parts, or get the tank supplier to write them down and take that list to your local hardware store. Don't forget the plumbers tape - to seal ALL the connection threads 😀  The majority of tank fittings are 40mm - both the inlet and outlet points. If you want to reduce that outlet size in order to connect a normal garden hosepipe, then your hardware store will know, and supply you with those fittings as long as you know the diameter of garden hose that you use. From tank outlet fitting size of 40mm to 1/2 inch garden hose = 12mm fittings, or 3/4 inch garden hose are 19mm fittings.

You will see two different valves in the pics - a plastic one and a metal one. Either valve can be used quite easily and is only dependent on what your hardware store stocks.

Cutting the water tank lid in order to insert the gutter downpipe can be achieved with the use of a utility / Stanley knife. Mark out the gutter profile on the lid, drill a "start" hole and cut away...

Shadecloth filter catching debris from our roof and preventing it
 from entering the tank

We use a piece of 80% shadecloth as our debris fiter and it works well. Hooking it over the water tank lid securing pin "protrusions" ensures that it is held in place.

It's easy to cut a hole in the top of the tank lid with a utility or
 Stanley knife

Also, when the lid is in position the "close fit" adds to that shadecloth filter position securiity. Ours have not moved in 7 - 8 years. Emptying the debris is as simple as lifting off the piece of shadecloth, shaking off the debris, and replacing the shadelcoth over the tank securing pin protrusions.

The lid helps to keep the shadecloth in position

First flushes are also easy to install and, if you go that route, I would recommend that you have a large mouthed valve at the end of the first flush pipe in order to facilitate easy expulsion / removal of the debris. Please remember to use a PVC weld if you are joining fittings with no thread. This is also obtainable from your hardware store.

Open source diagram of a first flush system

Another first flush diagram

If you want / need to connect your tank to your house you will need a pump and the knowledge of how to do this. If you do not know how to do this, ONLY then you would need to call on the services of a plumber.

I recommend a wide mouthed valve at the end of your first flush
 pipe to enable easy cleaning of the debris within

I know this seems to be a lot of info to absorb, but most of it is commonsense if you logically think about what you are doing.

Good luck 😀