In a previous article, we covered the question of whether multiple water tanks or one single tank would be the best option. If you believe multiple water tanks are the best way forward for your situation, then reading this article will give you some understanding about how your tanks can be linked. When installing your tanks, we recommend seeking the help of a professional plumber experienced with rainwater tank installations.
Two Methods of Linking Tanks
When connecting your tanks together with pipes, they can either be connected from the top via the overflow or at the bottom:
- Linking Tanks from the Top – the first tank fills up before water overflows into the next.
- Linking Tanks at the Bottom – allows all tanks to fill evenly together once a minimum water level is reached. When tapped, water is consumed in all tanks automatically.
Linking Tanks from the Top
Tanks can be linked together via the overflow of one being channelled into the other. As water fills up the first tank, it overflows into piping that leads into the inlet of your next tank. The opening of the overflow should be the same size as the inlet size. The last tank in the series has its overflow screened and leading to stormwater drainage on your property.
It is important to note that the maximum water level across all tanks in your system will be limited by the height of the overflow pipe from the first tank in the series. Given this, the first tank should be highest in elevation, and each additional tank in the series slightly lower.
When tapping your water, if you only tap your first tank, then water will always remain in your other tanks. One solution to avoid this issue is to tap all tanks into single connecting pipe below them. Water will then flow into this pipe allowing your all stored rainwater to be accessed. It is a good idea to have isolation valve on each so the release of water in a tank can be controlled.
While this setup is more complicated than linking from the bottom, it can provide you with the best of two worlds. Should you desire your tanks to fill up at the same time, simply open all valves. If you prefer tanks to fill individually, one after the other, close all except the first and open the next in the series as needed.
Linking Tanks from the Bottom
Connecting tanks together at the bottom with pipes from one tank to the next will allow all your water tanks to fill evenly. As rainwater enters your first tank, and reaches the height of your pipe link, rainwater will flow into your second tank until it attains the same height. At this point, both tanks will evenly fill up until full.
A benefit to this setup means you only need to tap off water from your first water tank, or lowest tank in the series. Furthermore, you will only need one overflow cut, making the pipework much simpler. Do note, the tops of tanks (overflow level) should be aligned with each other. This normally means placing lower tanks on a higher foundation and/or digging out beneath your taller tank.
It is important to include isolation valves if using this method, so that if one tank springs a leak, it will not drain all your tanks of their stored rainwater.
Keep in mind that this article is only intended to give you an understanding of the ways in which your water tanks can be linked and water accessed. Licensed plumbing is often a requirement when installing rainwater tanks in Australia, and we also recommend hiring a qualified professional. Hopefully, this article will at least provide you with enough understanding to discuss with your plumber how you desire your tanks to be connected and tapped.