How to fix a leaning rainwater tank?

[23lros23]

We bought our townhouse with a rainwater tank already installed in the courtyard, maybe in the range of 2500litre tank.

The tank has a rotted wooden frame around the outside and the base under the tank appears to be crushed something and not concrete.

Over the years the base has been washed away to now have the tank on a lean (as shown in photos).

Due the recent rain, the lean of the tank doesn't allow the pipes to remain connected or runoff to flow into the tank. The tank is currently full.

There is limited space between the tank and the back fence where the lean is occurring. Any suggestions on how to fix this issue

?Front on water tankBack of tankBase at back of tank near fenceSide of tank base and frameTap into ground water tank and baseShowing lean of tank

[MitchellMc]

Hi @23lros23,

The first step is to drain it to prevent further strain on the structure while you work. Since the tank is full, use a pump or a hose to siphon out the water, or if it has a tap, simply open it to drain the water slowly into a safe location. Once the tank is empty, you can more easily assess the situation. Begin by inspecting the extent of the lean and any damage to the tank's frame or the surrounding area. Pay particular attention to the condition of the base, which has eroded over time, leading to the lean. It’s important to determine whether the current base is salvageable or if a new, stable foundation is needed to support the tank’s full weight of 2500 kg. 

Given the limited space between the tank and the back fence, it’s important to ensure that any new base can be created within those confines, using materials that will resist erosion and provide solid support. A concrete base, gravel, or compacted crushed rock could be used to create a level foundation, ensuring that the tank is positioned correctly and securely. Once the base is prepared, carefully lift the tank back into position, ensuring it is level, and then reconnect the pipes to allow proper water flow. If necessary, consider installing a new frame around the tank to provide additional support and prevent further leaning. 

Since you've already experienced issues with a crushed rock base, I suggest installing a concrete base.

If you are not confident in creating this base yourself, I'd recommend enlisting the services of a professional.

Please let me know if you have any questions.

Mitchell