Rainwater Reuse WHAT TYPE OF SYSTEM? Click to edit Master text styles

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1 Rainwater Reuse WHAT TYPE OF SYSTEM?

2 What type of system? There are various systems that can be installed depending on the budget and the intended use for the water These range from Manual systems a simple tank with a tap to fill a watering can Pumped systems a system that replicates the full water supply system Full water supply systems replicates the water supply system

3 Manual systems what they are The most basic rainwater reuse system with the rainwater diverted into an above ground tank An overflow pipe returns rainwater to the drains when the tank is full The tank has a valve fitted that is used to fill a bucket or watering can

4 Manual systems advantages and disadvantages ADVANTAGES Simple low cost system DISADVANTAGES Reusing the water requires constant attention, often resulting in the water not being reused Tank must be above ground level

5 Pumped systems For reuse in fittings not requiring treated water The best compromise in that it allows a large percentage of the water used onsite to be rainwater, and ensures continuity of supply at all times A pump is used to pump water to the outlets where the rainwater is to be used To ensure that there is always water available, the system will also be connected to the mains water supply The pump controller, apart from starting and stopping the pump on demand, will need to have means of diverting to mains water when the rainwater tank is empty

6 Pumped systems issues to be aware of If connected to the mains there must be a backflow prevention device fitted to protect the mains water supply from contamination with the rainwater collected onsite Check minimum requirements with the local authorities Ask the system supplier to confirm that their equipment meets these requirements Rainwater Mains Water Garden only outlet supplied by rainwater only Outlet to home for toilet & laundry, supplied by Rainwater or mains.

7 Pumped systems switching from rainwater to mains water There are many possibilities, these are the most prevalent Float switch in rainwater tank to operate a solenoid valve at low water level Reducing the mains pressure to less than the pressure delivered by the rainwater pump, so water from the mains is only used when the tank water runs out or the pump is not running Using mains pressure to top up the rainwater tank

8 Pumped systems switching from rainwater to mains water Float switch in rainwater tank to operate a solenoid valve How does this work? When the water level in the tank is low, a float switch will activate a solenoid valve that switches the supply to the fittings from the pump to the mains supply Only select a system of this type that has an auto switch in the event of power failure This means that if the power supply onsite fails, the solenoid valve will automatically switch to mains water supply. This way the water supply will not be interrupted

9 Float switch in rainwater tank to operate a solenoid valve ADVANTAGES Will supply the mains water at mains pressure in the event of no rainwater in the tank or power failure DISADVANTAGES Requires installation of a float switch which can foul the water Will not automatically switch to mains pressure in the event of pump fault

10 Pumped systems switching from rainwater to mains water Using low pump discharge pressure to allow mains pressure into the system How does this work? Mains pressure is regulated by a pressure reducing valve If the pressure from the pump is low because of no water in the rain water tank, power failure or pump failure the mains pressure supply will automatically take over Typically the mains pressure will need to be regulated to 250 kpa KEY Blue = mains water supply Green = Rainwater supply Pink = garden outlet rainwater supply only Yellow = toilet & laundry (rainwater and mains supply Pos. Description 1 Non-return valve 2 Pressure-reducing valve 3 Mains water back-up 4 Double non-return valve 5 Rainwater from pump 6 PM Rain control panel 7 Rainwater outlet 8 Rainwater and mains water outlet

11 Pumped systems switching from rainwater to mains water Using low pump discharge pressure to allow mains pressure into the system ADVANTAGES No external control devices required Complete security of supply in the event of power or pump failure DISADVANTAGES Mains water supply is is limited in in pressure

12 Pumped systems switching from rainwater to mains water Using mains pressure to top up the rainwater tank How does this work? The mains water will be connected to the rain water supply though the rainwater collection tank If the water level in the tank becomes low a float switch will activate a solenoid to top up the tank

13 Advantages and Disadvantages of Using mains pressure to top up the rainwater tank ADVANTAGES If correctly installed with the mains water supply providing an air gap, no back flow prevention is required DISADVANTAGES Requires installation of a float switch which can foul the water The pump is required at all times so in the event of a power failure or pump failure there is no water supply

14 Pumped systems Benefits compared with manual systems All three control variations have one major advantage over the manual system The rainwater collection tank can be installed either above ground or below ground Placing the tank underground creates more space for lawn or garden and removes it from sight Before installing an underground tank, check with the supplier first, as some may require a submersible pump for these types of installations Above ground self priming pump with interconnect device Submersible pressure booster with interconnect device

15 Full water supply systems requirements A pump and water treatment system that is capable of supplying all of the requirements for the house Rather than feeding just a few outlets, this will supply everything To ensure continuity of supply, it should also be connected to the mains water supply by one of the methods described previously If you have completed Grundfos Ecademy Topic Cold Water Boosting you will have a good understanding of the requirements for this option

16 Full water supply systems advantages and disadvantages ADVANTAGES Able to use rainwater for all outlets, meaning lower reliance of the mains supply. DISADVANTAGES Will be higher cost due to the requirements for larger flows and water treatment. Ongoing maintenance will also be higher as the water treatment system will require on-going attention.

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