Choosing a water tank can at times be a very confusing task. But with a few simple steps it should be a lot easier.

Before looking for a water tank, you should first ask yourself what it is you want to achieve, what you want to use the stored water for. Are you going to use the water to flush your toilets? Do you want it for your gardens or gardens and lawn? Or do you want to top up a spa or swimming pool? Or maybe even all of the above. Once your requirements are established, you need to determine if there is sufficient rainfall in your area and also if you have an adequate sized roof to capture the rain. Then you must decide upon a suitable location for the water tank, keeping in mind that a water tank can be a bit of an eyesore, so if possible try and place it where it does not stand out too much. You can however, cover them with a lattice wall or some form of screen should you want to cover them up.

One thing to keep in mind is the distance from the water tank or tanks to the down pipe which is to be used to capture the water. The longer the distance, more plumbing will be required. Also you will then have a choice of having your plumbing in the air exposed or under the ground creating a wet system.

Now that you have a location and know what capacity water tank you need, you then have to find a tank whose physical dimensions can fit in your location. Whether you choose a round or slimline tank, sometimes due to space restrictions you might have to choose smaller tanks, but more than one to achieve your capacity requirements.

In my situation due to space restrictions and my planned water requirements, I had to use multiple slimline tanks. I chose my tanks because of their construction, strength (they looked sturdier and stronger than other tanks I had looked at. There are some which have been known to bow out slightly when they are full), the other thing was their appearance (they are somewhat pleasing to the eye, as far as tanks go!) And as a bonus they are manufactured locally and come with a 25 year warranty. The tanks I used are 3000litres each and are made by a company called SupaTank. There are many dealers out there selling these tanks and in other sizes also, so it is not hard to obtain. I am extremely happy with this product and would not hesitate to recommend it to anyone.

Installing a tank is pretty straight forward. All that is required is a firm level base such as compacted sand or on a concrete slab. For my tank installation, I went for the concrete slab with reinforced F62 Mesh because the chosen tanks are slim tall and long, are close to the house and fence line, and when full there will be around 9000Kg of weight. SupaTank recommends that the tanks be sited on ground that is of a very stable nature and has a reinforced (F62 reo mesh) concrete slab.

Once the tank or tanks are in position you then need to connect them up.

Firstly drill a hole into the side of the tank as per the manufacturer’s instructions. The SupaTank has several 25mm BSP brass female outlets which are moulded into the wall of the tank. I drilled only the outlets that I required. There is a dimple in the centre of the wall inside the outlet to assist with centering the drill bit or long shaft hole saw. It is suggested that a hole up to 22mm in diameter be drilled into the wall of the tank outlet for optimal water flow.

Once the hole is drilled, you can then screw in a suitably sized nipple and tighten. First make sure you cover both ends of the nipple with a good quality plumbers tape (see image at the bottom of the page). This will ensure a water tight seal.

Please note when installing the nipple to the tank take extreme care not to cross thread or over tighten as this may cause damage to the brass outlet.

Once the nipple is attached, you can then attach a ball valve. Also note that when screwing the ball valve onto the nipple it pays to also hold the nipple so it does not turn and damage the tanks threaded brass outlet.

If you need to connect two or more tanks in line, then on the end of the ball valves you will need to connect a barbed piece (see image at the bottom of the page), also remembering to use the plumbers tape. You can then join both barbs with re-enforced flexible hose and clamp tightly with hose clamps.

Now the easy parts are done!

Next we need to connect the tank to the gutter / down pipe and we also need to connect the tanks overflow back to the storm water system. I suggest that a day of no rain is considered for this job, as it will take several hours, even if you have all the parts available. You don't really want to have a disconnected down pipe while it is raining!

In my system I used a feeder tank, which as the name suggests feeds into my main storage tanks.

You might notice that the overflow in my configuration is taken from the feeder tank and not the main water tanks. This is because I did not want to have plumbing across the pathway, and down the large tanks.

What I did was to install a very slim tank, known as the Nylex Freewater Slimline Tank, up against the house wall, and it was crucial to get the height of the overflow of this water tank correct.

As you can see in the picture this feeder tank is sitting on a strong wooden stand i made to support it, and to get it to the required height.

The height is very important because if the feeder tank overflow is too low then the main tanks will never be able to hold their maximum capacity (that would be a waste), and if the overflow is set too high then the overflow from the feeder will never work and the main water tanks will overflow causing the area to flood.

Using my new toy the Bosch PMF 180 E multi tool, I cut the PVC pipe at the bottom of the existing down pipe. I then removed the brackets holding the down pipe. This then made removing the pipe easy. I installed a Leaf Eater which basically prevents leafs and other unwanted objects from entering your pipes and eventually your tank.

The Leaf Eater consists of a mesh screen set on an angle which allows water to penetrate through, but unwanted debris rolls off the mesh screen. Inside the Leaf Eater there is a fine mesh screen which is there to prevent mosquitoes from breeding.

Below the Leaf Eater there is a device called a First Flush water diverter. This simply is a T section of PVC pipe which is connected to another pipe and then capped. This pipe has a ball in it which when it rains, the first run off from the roof which will be the dirtiest, will run straight down the pipe filling it. As the pipe fills, the plastic ball floats to the top then blocks a section of the PVC T piece, causing the cleaner water to divert to the feeder tank.

The cap at the bottom of the First Flush system is removable for maintenance. The cap contains a long plastic filter and a rubber seal with a small hole in the middle. The filter is there to help prevent the hole in the seal from clogging up. The seal is what allows the First Flush to self drain. The time it takes to drain can be adjusted by replacing the rubber seal with one of the other seals supplied. Each seal supplied has a slightly larger draining hole.

Note the Y section of PVC plumbing. I installed this because I did not want the First Flush to just drain itself straight into the ground. With this system it drains into the Y section. I capped the Y piece with a fine mesh cap to allow water but not mosquitoes or other creatures. Oh, and also in case my kids decided it would be fun to jam a toy in there!

All plumbing used was 90mm PVC pipe, and I used a primer solution to first clean and prepare the pipes before using the clear cement to glue them together. Using the primer followed by cement makes for a stronger bond.

Keep in mind when gluing the pipes, that if you use blue or green cement glue, it will show up on the pipe joints especially if you use too much glue and it runs.

Connect all pipes up without glue first to make sure everything sits correctly. Once you are happy with their positioning, take them apart and glue them. Keep in mind that once the glue is applied they bond very quickly. So it is very important that you get your pipes in the right position, mark them, then take them apart and glue using the marks on the pipes as guides. This is specially the case when joining several elbows or angled pieces at different rotations.

The feeder tank is connected through a ball valve to a small section of re-enforced flexible hose then to some pressure pipe. The pressure pipe is 20mm PVC pipe which was primed glued and connected to the feeder tank and to the bottom of one of the main tanks, via a section of re-enforced hose. This is the water supply into the SupaTank storage tanks. The pressure pipe has been located under ground to keep it out of the way.

The connection from the feeder tank ball valve, to the PVC pressure pipe was made using re-enforced flexible hose, as were all connections between the main tanks. This allows for any future repairs or removals to be made easier. Note also that every tank has been fitted with a ball valve where an outlet has been used. In the event that a problem occurs with any of the main tanks they can individually be isolated. At present there is only one feeder tank in operation, which if the first main tank is isolated, then the others will not fill. But a second feeder tank is in progress, as was originally planned, which will enable the isolation of each water tank should it be required. This will double the amount of water which is captured, and will allow for faster water replenishment.

Hopefully this has helped in some way towards setting up your own system.