Rainwater storage tanks: how to select and install rain water tanks
Rain Water Usages
If you have been following along with my other Hubs on collecting rainwater you will have discovered that the combination's of Shapes and Sizes of Rainwater storage Tanks is virtually infinite!
This Hub is to give a broad outline of selecting and installing a tank. (Please read the warning below).
The first thing you need to do is decide just what you are going to do with the water you collect?
Here are some possibilities of uses for the water, the list is by no means complete:
- Complete House hold use
- Laundry and toilet flushing
- Showers and Bathing
- Garden Watering
Size of Water Storage Tank required
Before you select your Water Storage Tank you need to calculate just how much water you need to collect for your needs. This exercise is just for getting enough water for the garden.
Now lets say your normal house water supply delivers water at approximately 20 psi which translates to about 2 gallons (10 liters) a minute (this all depends on the water supply, the condition of your pipes etc.), so if you water the garden for one hour you will be using 120 gallons (600litres) / hour. Maths is not my strong-point so if I am out in my calculations will some one let me know?
According to research this figure is close to what the average family uses per day in Australia and America!
Rain Water Tank - Poly round
Rain Water Tank - Poly
The installation I want to concentrate on here is for watering the Garden using a Poly (Plastic) Water Storage Tank as the other uses would very likely require the services of a Licensed Plumber.
Alright, based on the figures explained before the closest tank I can find for your to use is a 220 gallon (1000litre) tank. This tank is a round tank which measures about 3ft (900mm) in diameter and stands about 6feet (1.8metres) tall.
See the above image.This is a photo of our own tank that we have installed at our place.
The next decision is whether you want to gravity feed from the tank or purchase a pump to run sprinklers and a hand held hose from the tank.
If you do not want to run a pump and most people in this situation would not, then I would suggest that to gain some pressure you place the tank on a platform. Keep in mind that when the tank is full 220 gallons of water does weigh quite a bit so the platform would have to be substantial.
Next is to find a location for the tank . I would suggest close to a wall or tucked up the side of your house, somewhere close to the down-pipe of the guttering system around the roof of your house.
Rain Water Tank Gate Valve
Rain Water Tank Gate Valve - How they work
Supplies and Tools
There is not a lot you need to fit this tank and here is a list of items that you may use starting with the supply and then the tools:
1 x Poly (Plastic) Water storage tank to you selection
1 x First Flush device (optional) There are many different types available I would suggest to use the ball type it requires less maintenance in fact if you are a handy-person you can make them yourself.
1 x Length of pipe 4 inch to suit the size of your down pipe
1 x adapter for pipe
1 x faucet (tap) word of caution here I would suggest to go for what is termed a 'gate valve' as there may be some time between uses the valve in a normal tap or faucet may stick due to lack of use and low pressure.
1 x PVC Glue for pipes
Packing sand or concrete block / platform for underneath the tank.
half round file
Hammer (don't know what you will need it for but every job needs a Hammer)
1 x Foreperson. (must be PC here) That said person will more than likely come in the form of a female :-)
Rain Water Tank typical installation
Plumbing the Tank
Now you have gathered all of your supplies and borrowed the tools from your neighbors we can start the installation.
Look around an find a nice place for the tank preferably close to the down pipe. Carry out the preparatory work on the substrate under the tank. i.e. packing sand, platform, concrete block etc. .
The down-pipe will have to be broken and I would suggest that a 'first flush' device be fitted to the down-pipe coming from the gutter. These 'first flush' device take up the first few gallons of water coming from the roof to remove all of the rubbish washed down from the roof, then feed the clean water into the tank.
From the outlet of the 'first flush' device there is a connecting pipe to the top of the tank.
From the outlet of the tank (the hole just down from the top) a pipe is run to the other end of the down-pipe. This is for when the tank fills up the overflow will go back down the storm water drainage system and not under your house.
An outlet tap can be fitted to the hole provided, which is about 18 inches above the bottom of the water storage tank!
Rain Water Tank - first flush system
If you intend to integrate the installation of water storage tanks with your Town water supply you should first check with your water authority. You may find that the work must be carried out by a Licensed Plumber.
Also some State authorities insist that any plumbing work at all carried out must be done by a Licensed plumber.