Any Rainwater Tank level control system consists of four elements:

• A tank
• Rainwater harvesting
• Mains-water
• Controller

The key objective is to maximize the storage and use of harvested rainwater while minimizing the use of mains water. This requires a delicate balance as we experience fluctuating periods of wet weather and droughts with little warning. During wet periods the water tanks are full, but in the increasingly common dry summers, the tanks run low. Depending on usage, this can lead to various problems, from sanitation issues (such as yard washdown and toilet flushing) to maintenance issues (such as pump damage due to running dry). Not to mention the alarmed calls from sites/users when things don’t run exactly as expected. this is the point where an end user will ask ‘What’s the point of this system if it doesn’t work without rain?’ followed shortly by ‘To hell with it, I’ll just use the mains instead’.

RainControl for tank level control

At this point, we can pull a RainControl from our sleeve, either in the design stage or retrofitting to a pre-existing tank installation to add both level monitoring and top-up functionality.

The RainControl is designed to be DIN-rail mounted, allowing for installation in both panel mount systems or as a standalone unit in a windowed project box. The RainControl panel displays the live level inside the tank along with top-up status. It uses a pressure transducer, which eliminates the need for moving parts inside the tank, simplifying installation and use as only one input has to be configured.

Now, unlike the majority of ‘simple’ or ‘basic’ top-up systems, the RainControl doesn’t add water to the tank for a specific amount of time, rather the RainControl can be configured to add a measured amount of water. This allows the installer (or end user) to set or adjust the minimum and maximum intervention levels inside the tank. When properly configured, this ensures that there is always a minimum level of water in the tank. When the RainControl detects that the water level has dropped below the minimum set level, it opens a solenoid or motorized valve to top up the tank until it reaches a specified maximum level. Once the tank is filled to this level, the RainControl closes the valve or solenoid until the water level drops again to the initial minimum point.

RainControl for Tank Emptying

We could use the same simple system to drain a tank. Turning this on its head, rather than filling a water tank, the relay inside the RainControl could be connected to a pump rather than a valve. So using the same setup (and just a touch of cunning) we can set the operational levels for draining a tank once it reaches level ‘x’ turning off the pump at level ‘y’.

This is an interesting idea for SuDS systems if we use an attenuated outflow on a motorised valve rather than a pump. The RainControl is a robust reliable system at a very competitive price point.

RainControl for Tank Level Alarm

The use of pumps/valves (and solenoids) is certainly one avenue. The RainControl could also easily be adapted into a high/low-level alarm using the relay to activate an alarm rather than a pump or valve. Again, it’s robust, simple to configure and install and competitively priced.

RainControl from Mac3

As with much of the Mac3 line, there are multiple uses for any given piece of equipment given a little design thought. The RainControl is a flexible addition for any parts list if building a controller from scratch, adapting an existing installation to a new purpose (always good fun) or simply replacing a failed system, there will always be a use for the RainControl.

Why not contact us if you have a thought about how you could use one of these anew, or to repair a failed system. We particularly love fixing redundant Rainwater Harvesting systems and bringing Rainwater Harvesting tanks back into use.

For more information

Contact Jim, our Mac3 Technical lead. Jim and Tom have over 25 years of experience in Water Control Systems.

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