A rainwater harvesting system generally consists of four main components and these are:
1. Underground storage tank
The Freerain underground storage tank is firstly made by us in the UK, it has been designed to hold good volumes of water, whilst keeping the excavation depth to a minimum. The tanks are made with virgin polyethylene plastic, allowing for a non-concrete base and backfill installation. (pedestrian loading only). The tanks come pre-fitted a BS8515 required calming inlet, in-tank filter and a telescopic neck with pedestrian cover. (see individual system pages, for dimensions). The tank has three DN100 spigots, these are used for rainwater inlet, overflow outlet and the third as a service duct. Note, larger tanks have an optional secondary neck to allow for much larger filters for extensive roof areas.
The systems are pre-fitted with a suitable filter (some system sizes have optional filter upgrades), this filter is installed into the neck of the storage tank and removes leaves, moss and other debris from the incoming water. The clean water simply washes through into the tank. The filter contains no consumable parts and therefore it only needs to be cleaned by simply washing the mesh under a running tap, a few times per year (2-3 on average). The filter is approximately 95% efficient, meaning very little water is actually wasted.
3. Submersible pump
The pump in a rainwater system is really the only moving part of the whole system and therefore, it is important to ensure a good quality pump is used. Another important point is that we only use submersible pumps in our rainwater harvesting systems. Some other systems use surface-mounted pump sets, sometimes also suction systems. The main disadvantages of these systems are larger, noisier kit in the house and secondly, the pump is having to suck the water out of the tank and this is known to be less efficient than pushing the water, as a submersible pump does.
Freerain systems use the direct pressure system, water is delivered directly to the point of use and the pump is energised until the resting pressure in the pipe-work is restored. Mains water is then fed back into the storage tank to hold a minimal volume of water in the event of low rainfall. The system includes a class AA air-gap as required by water regulations.
Accessories and other items
The Freerain systems come complete with all the necessary parts to make a system work, they also include all the identification markings and signs to comply with water regulations. A roll of green/black MDPE pipe, which runs between the submersible pump and the controls is included too.
If connecting the overflow from the tank to a storm drain or if there is doubt over the effectiveness of the soakaway, then it is prudent to add the optional "one-way valve" to the system. This protects the tank from overflow water entering the tank.