Rainwater Collection

The 4 Stage Cleaning Process

With good planning and the right components a rainwater system can be nearly maintenance free and the rainwater quality is ideal for many uses, in both the home and the workplace. A professional system will have four stages of cleaning of the rainwater.

Roof Areas

Only rainwater from roof areas should go to the storage tank. Smooth surfaced materials are the best (slate, tiles, glazed cement roofing slab). The rain yield from green roofs is 30-50% and whilst it can sometimes be a bit discoloured it is still suitable for toilet flushing and garden watering.

1. Filter

The first cleaning step in the rainwater system is the filter. The rainwater flows from the roof to the filter. Here dirt particles and debris are separated from the water. The cleaned water flows to the tank. The dirt is washed to waste or soakaway with a small amount of rainwater. All rainwater filters have stainless steel inserts, which are easy to remove and easy to clean. Their many different working principles and connection possibilities allow for their use in many different installation situations.

2. Calmed Inlets

By using an underground tank, the water is stored in dark and cool conditions. Here the second cleaning step takes place. In the water column, any fine residual particles settle to the bottom of the tank. The rainwater Calmed Inlet prevents any disturbance of this sedimentation layer. At the same time the Calmed Inlet ensures that oxygenated water is introduced to the lower layers of the stored water in the tank. This oxygen rich water prevents anaerobic reducing conditions forming in the storage tank and ensures that the water stays fresh.

3. Overflow Siphon

Any particles that are lighter than water(e.g. flower pollen) float slowly to the water surface. The expertly designed Overflow Siphon, with a skimmer effect, removes this floating layer. The regular overflow from the storage tank is important to get the optimum water quality. It prevents souring of the water. The floating layer could otherwise build up over time, and so reduce oxygen diffusion at the water surface, which in turn could lead to anaerobic reducing conditions in the tank.

4. Floating Pump Intake

The Pump Intake floats at all times, suspended just below the water surface where the cleanest water lies. From this position the water is extracted by the pump. A ball float, filled with air, suspends the intake, which has a further filter and a check valve.