When you first start rainwater harvesting, you might underestimate your water needs. Or perhaps you didn't have the budget or space for a massive single tank right away. The good news is that expanding your system is completely possible. Let's delve into the techniques behind Connecting Multiple Tanks for increased storage capacity.
The Basics of Daisy-Chaining
Daisy-chaining refers to linking two or more rainwater tanks together so they behave as a single, larger storage unit. This is an excellent solution for properties with limited access for large delivery trucks or those with awkward spaces like narrow side yards where only slimline tanks fit. The primary goal is to ensure that water flows freely between the tanks, maintaining a balanced level across the system.
Top Linking Methods
The most common way to connect tanks is via the bottom valves. By connecting the outlet valves at the bottom of each tank with a linking pipe, water will naturally balance between the tanks based on principles of fluid dynamics. For this to work perfectly, the tanks should ideally sit at the exact same elevation. If one tank is significantly higher, it will attempt to overflow into the lower tank until the levels equalize.
Alternatively, some people link tanks at the top via the overflow. When the first tank gets full, the excess water spills into the second tank instead of going to waste. While easier to set up, this method has a drawback: you have to draw water from the first tank, and the water in the second tank can become stagnant if not used regularly.
Important Considerations for Bottom-Linking
If you choose to link tanks via their bottom outlets, consider installing isolation valves between them. If one tank springs a leak, an isolation valve lets you shut off the linking pipe immediately, preventing you from losing the water stored in the remaining healthy tanks.
Pipe size matters. For a linked system to balance quickly during a heavy downpour, the linking pipe needs to be adequately sized—typically 1 to 2 inches in diameter. If the pipe is too thin, water might enter the primary tank faster than it can transfer to the secondary tank, leading to an overflow even though the second tank is mostly empty.
Foundation and Elevation
When placing multiple tanks side by side, ensuring a uniform and level foundation is crucial. If the tanks are of different heights, the maximum fill line of the system will be determined by the lowest overflow point. To maximize capacity when mixing a tall tank with a short tank, you might need to build a specialized stand for the shorter tank so its top overflow aligns perfectly with the taller tank's overflow.
Conclusion
Connecting multiple tanks is a flexible and scalable way to build an impressive rainwater harvesting setup. Keep isolation valves accessible, ensure your foundations are absolutely solid, and enjoy the peace of mind that comes with abundant water storage.