Filtration and Disinfection
Although captured water quality can be compromised by debris picked up from the collection surface, it is still suitable for non-potable purposes provided it is processed by a system that has been correctly designed and installed. The use of high-quality components and proven system design principles allows Polypipe Rainstream systems to meet the requirements of BS8515.
The Filtration Process
Water arriving at the filter is distributed evenly across the full width of the filter cascade. The cascade pre-cleans the water by diverting the larger particles of debris away to the sewer. Water then flows over the secondary filter sieve where a special mesh allows the remaining dirt particles to fall away to the sewer. Cleaned water flows into the storage tank ready for re-use.
The Rainstream range offers a wide variety of filtration options, ranging from basic leaf filters to systems capable of removing metals, oil, chemicals and even bacteria such as legionella. Polypipe's experts are onhand to help you choose the most appropriate option for your application.
The Disinfection Process
The captured water passes through a disinfection unit where it is exposed to a high level of
ultraviolet radiation. This alters the nucleic acid (DNA) of any viruses, bacteria, moulds or parasites and prevents them from reproducing, leaving the water chemically unaltered while improving the quality. This is a particularly important process where those people more susceptible to infection may come into contact with the recycled water particularly the very young or the elderly. If this is likely, or if the water may be used in an aerosol form - e.g. a vehicle wash-down area - Polypipe recommends that a risk assessment is carried out to ascertain the need for ultraviolet disinfection.
Rainstream tanks for below-ground installation represent a practical and effective way to accommodate a large part of the rainwater re-use system and preserve the appearance of the site. Below-ground installation protects the captured water from fluctuating temperatures and exposure to sunlight.
Manufactured from GRP they are available in capacities that range from 1,500 - 300,000 litres. A variety of duty types are offered which can be buried between 1 - 4 metres from the surface to accommodate different site conditions.
Rainstream above-ground sectional tanks are also available in capacities from 2,000 litres upwards. Manufactured from tough pre-insulated GRP panels they offer exceptional design flexibility and allow tanks of different sizes and shapes to be created to suit individual projects. These tanks are suitable for installation inside buildings once they have been constructed.
Designed with a flat bottom for installation ontoa hard-standing surface, Rainstream above-ground one piece tanks are manufactured from rugged Glass-Reinforced Plastic (GRP). Their one-piece construction provides maximum strength and robustness and they are available with capacities ranging from
6,000 - 36,000 litres.
Pumps and Controls
A variety of accurate and reliable pump and control options allow Rainstream systems to offer a high degree of flexibility.
The standard Rainstream control set includes a single pump assembly, inline filtration unit and a control module compatible with both gravity and pressure operated systems. In a gravity system the control unit constantly monitors the water level in the header tank, automatically drawing in more water from the main storage tank if required. The storage tank is also monitored so that fresh mains water can be imported if needed. This ensures that the header tank always contains the minimum water volume required for safe operation.
For a pressure system the control unit automatically detects any demand for water and delivers a pressurised flow to all outlets. If the storage tank volume drops below the minimum, the control unit draws in sufficient mains water to ensure that the required output level is maintained.
Duty Standby Systems
Rainstream duty standby component sets include a double pump assembly, in-line filtration and a control module suitable for both gravity and pressure-fed systems. This maintains efficiency, increases operating life and ensures continuity of supply even in the unlikely event of one pump failing.
Rainstream advanced pressure-fed systems provide the most reliable control over the water supply and feature a duty standby function which delivers a constant supply of water to all outlets. The storage tank level is constantly monitored and if necessary the system will switch to using fresh water to maintain the supply
at the outlets.