In a previous article, we addressed the question of whether multiple water tanks or just one would be the best option. If you feel that multiple water tanks are the best way forward for your situation, reading this article will give you an idea of how your tanks can be linked together. When installing your tanks, we recommend seeking the help of a professional plumber experienced in rainwater tank installations.
Two Methods of Connecting Tanks
When connecting your tanks with pipes, they can be connected from the top through the overflow or from the bottom:
- Tank connection from the top: the first tank is filled before the overflows into the next one.
- Link Tanks at Bottom: Allows all tanks to fill evenly once the minimum water level is reached. When opened, water is automatically consumed in all tanks.
Tank connection from the top
Tanks can be linked through the overflow of one that is channeled to the other. As the water fills the first tank, it overflows into the pipe that leads to the inlet of the next tank. The overflow opening should be the same size as the inlet. The last tank in the series has its overflow protected and leads to stormwater drainage on your property.
It is important to note that the maximum water level in all tanks in your system will be limited by the height of the overflow pipe of the first tank in the series. Keeping this in mind, the first tank should have the highest elevation, and each additional tank in the series should be slightly lower.
When removing the water, if it only touches the first tank, then the water will always will remain in the other. tanks A solution to avoid this problem is to connect all the tanks to a single connection pipe below them. The water will then flow into this pipe, allowing access to all the stored rainwater. It’s a good idea to have an isolation valve on each so you can control the release of water into a tank.
While this setup is more complicated than connecting from the bottom, it can give you the best of two worlds. If you want your tanks to fill at the same time, just open all the valves. If you prefer tanks to be filled individually, one after the other, close all but the first one and open the next in the series as needed.
Connecting tanks from the bottom
Connecting tanks together at the bottom with piping from one tank to the next will allow all your water tanks to fill evenly. As the rainwater enters your first tank and reaches the height of your pipe joint, the rainwater will flow into your second tank until it reaches the same height. At this point, both tanks will fill evenly until full.
A benefit of this setup means that you only need to draw water from your first water tank or the lowest tank in the series. Plus, you’ll only need one overflow cutout, which makes plumbing installation much simpler. Note that the tops of the tanks (overflow level) must be flush with each other. This usually means placing your lower tanks on a higher foundation and/or digging under your taller tank.
It is important to include isolation valves if you use this method, so if a tank has a leak, do not drain the rainwater stored in all of your tanks.
Final comments
Please note that this article is only intended to give you an understanding of the ways in which your water tanks can linked and access to water. Licensed plumbing is usually a requirement to install rainwater tanks in Australia, and we also recommend hiring a qualified professional. Hopefully this article will provide you with enough understanding to discuss with your plumber how you want your tanks wired and connected.
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