Fail-safe features on a Rainwater Harvesting System

Rainwater harvesting systems are a proven technology that can dramatically reduce mains water consumption within a building. Rainwater harvesting is the process of capturing and recycling perfectly clean rainwater that lands on the surface of the roof area. Recycled rainwater can provide a sustainable water supply for many typical uses of water within a building, including toilet flushing, irrigation, and cooling purposes. Traditionally, these non-potable uses of water would have been covered by mains water supplies. Mains water is treated to a high quality and this level of treatment is not required for non-potable use.

Selecting the right rainwater harvesting system for the building is important as the system will be operational for a long time. Rainwater harvesting systems supplied by reputable manufacturers will also have many fail-safe features included to ensure the rainwater harvesting system can still provide a water supply to toilets in the event of a component failure.

British Standard BS 16941

The British Standard for rainwater harvesting was first introduced in 2009 to give suppliers a minimum standard to meet, in terms of system sizing, operation, and maintenance.

British Standard 16941 ensures that the sizing of the mains storage tank is based on 18 days’ worth of storage. Sizing the rainwater harvesting system on 18 days capacity ensures that the system will be covered against the average drought period in the UK.

The British standard does not cover sizing of the internal storage capacity on a rainwater harvesting system. Most forms of rainwater harvesting systems will have some kind of internal storage capacity whether that be a break tank, header tank, or pressure vessel. This should be adequately sized to ensure there is always a water supply available to points of use. Simply reducing the internal storage due to the ability to top the break tank with mains water can result in the break tank not being able to meet the demand. Reducing the size of the break tank can also mean the system is reliant on mains water more frequently.

Fail-safe Features

Stormsaver rainwater harvesting systems also have many fail-safe features that can protect end users from system downtime. Learn more about some of the features below.

Mains water solenoid

Every rainwater harvesting system that is designed to be compliant with BS 16941 will have an automatic mains water top-up facility. This mains water top-up consists of a physical air break between the mains water and rainwater supplies to prevent cross-contamination. The automatic top-up also includes a solenoid valve which will open when there is a low level of rainwater available in the main storage tank to allow the break tank to be filled with mains water. This ensures there is always enough capacity within the break tank to cover the demand.

The solenoid valve on the mains water top is powered closed by the control panel when a mains water supply is not needed. This means that if there is a failure within the electrical system, the rainwater harvesting system will be able to top up with mains water providing a continuous supply to points of use.

Mechanical ball valves

Stormsaver also manufactures combi and non-pressurised rainwater harvesting systems to have a mechanical ball valve on the inlets of the break tank. Without maintenance, solenoid valves can easily become stuck partially or fully open allowing water to enter the break tank continuously. The mechanical ball valve on a Stormsaver system will mechanically operate once the desired level of capacity within the break tank has been met. Without a mechanical ball valve, mains water could be wasted continuously until the next service visit should the solenoid valve fail open. If a failure were to happen without a mechanical ball valve, a large water bill could be received by the end user.

Dry run protection

All aspects of a Stormsaver rainwater harvesting system are in constant communication with the electrical control panel. Stormsaver systems have a rainwater and mains water meter which measures the flow of the water supply running through the system. If there is no flow detected through these meters, our system will activate the dry run protection for the pumps. Without dry run protection, a pump can quickly degrade.

PLC control panel

Stormsaver rainwater harvesting systems are manufactured with PLC electrical controllers. If a relay fails within the PLC control panel, then this can be easily replaced. If a more common PCB electrical controller fails, the unit will need complete replacement. The electrical controller is essentially the ‘brains’ of the system. Without the ‘brain’ working properly, the client could be left with no non-potable water supply to points of use.

Learn more

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