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Benefits of Linking Multiple Rainwater Tanks

Benefits of Linking Multiple Rainwater TanksLinking rainwater tanks together is an easy way to increase your water storage capacity without significant plumbing work. This article will consider some benefits that linking multiple rainwater tanks together can provide you with.

Better Tank Prices

A primary reason for linking multiple water tanks, is that often with water tanks there is an ideal price point per litre. 5000 gallon tanks (22,700 litres), for example, are a popular option and very competitive tank size. Therefore, the price point on these can often work out better than smaller or larger tank options.

Lower Maintenance Costs

Very large steel tanks can be quite expensive, as well as difficult to setup. There is also a cost to maintaining your rainwater storage system over time. It will be much less expensive to fix and/or replace one poly tank of say four 22,700 litres in a series, then it would be to replace a 100,000 litre steel tank. Linings also need fixing and/or replacing over time, and this can be quite costly with larger tanks.

Maximise Capture of Rainwater Harvestable

Another good reason is where you have many rooftops or perhaps good locations at more than one downpipe. A better option to maximise storing the high volume of water you can potentially harvesting, is to link several tanks together and make use of a wet water system (downpipes lead to an underground piping system to your rainwater storage location).

Expandable Water Storage

If you are unsure of how many water tanks you will need, or perhaps you might need to store more water in the future, then a multiple water tank setup obviously means you can add more tanks as needed. You just need to ensure that you have adequate space on your property for installing another rainwater tank.

Water Storage Fault Tolerance

Should a water tank become damaged, fail and leak, then obvious in a single tank setup your only option is to lose your water. Your tank will likely need to be completely drained before the problem can be fixed, or when you install a replacement tank.

A more modular water storage system, like a multiple water tank setup, means should one tank spring a leak then you don’t stand to lose all your rainwater. That tank can be isolated and/or have water pumped into your other tanks before it is fixed and/or replaced.

In summary:

  • Multiple tanks can be more cost-effective than buying one very large tank
  • Multiple tanks can have lower maintenance and replacement costs than one very large tank
  • Multiple tanks provide a convenient way to maximise rainwater harvesting with multiple roofs or many downpipes
  • Water storage can be expanded with extra tanks as needed
  • Multiple water tanks provide higher fault tolerance due to modular nature (if one tank is damaged, it can be fixed or another ordered while the other tank/s still harvest rainwater)

Linking Tanks to Fill Evenly

To link tanks together so that they both evenly fill is accomplished by linking the tanks together near the bottom at their sides with piping. As your first tank fills up and water reaches the height of your 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 and/or pump water from your first tank (or tank that is lowest). Equally only one overflow is required in such a setup. It is important with tanks of different heights, that the tops (overflow) be aligned with each other. This normally means raising the smaller tank up on a higher foundation, or digging out beneath your taller tank before establishing its foundations.

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.

Linking Tanks to Fill One at a Time

Tanks linked in series through their overflow will result in your first tank needing to fill up before rainwater flows into the next. The last tank in the series is setup with an overflow to expel excess water to your storm water drainage as per a normal single tank setup.

To use water in all your tanks, each tank needs tapping and/or to be connected via piping at your desirable outlet level on their side. All tanks are piped from their outlet to underground piping that leads to your pump.

Again, you should have isolation valves at your tank outlets so the release of water in a tank can be controlled. This setup while more complicated, also can provide you with the best of both worlds should you desire tanks to fill up at the same time, simply open all valves. If individually, one after the other, close all except the first and open the next in the series as needed. This can be performed manually, or auto-switching can be setup to refill your storage tank should it drop below a certain level.


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