How to make rainwater management work

Waterscan's innovative Aqua-Control systems have been approved to join the UK Enhanced Capital Allowance scheme. Neil Pendle outlines the driving forces that are expanding the commercial rainwater management market.

Rainwater management involves the interception of rainwater that would either have gone down drainpipes into the municipal drainage and sewerage systems, soaked away into the ground, or have been lost to atmosphere through evaporation. In commercial applications, large surfaces such as roofs, car parks or driveways are ideal for rainwater collection.

Stored water can be used in cleaning processes, to flush toilets, or to irrigate gardens and agricultural land. Rainwater collection and distribution systems can be installed in both new and existing buildings, and the alternative water supply can be used for essentially all purposes except direct potable use.

Large commercial properties, such as supermarkets and other retail outlets, with large roof areas, can consume significant quantities of water supplied by the local water company. But this water is becoming more expensive, and only a small proportion is subsequently used for direct potable use.

Using rainwater appropriately, such as in conjunction with water efficient devices including dual-flush toilets or tap timers, can save up to 75% on potable water bills. The use of rainwater instead of potable water reduces pressure on our environment, and helps to conserve valuable drinking water resources.

The UK government has recognised the importance of effective rainwater management by adding rainwater management technology to the Water Technology List. This list, managed by Envirowise, a Defra programme providing practical environmental advice for UK business, includes details on a range of products that have been approved for receiving enhanced capital allowances (ECA).

The ECA programme enables UK businesses to claim 100% first-year capital allowances on investments in environmental technologies, such as Waterscan's Aqua-Control rainwater management technology, and other products that encourage sustainable water use and efficient use of energy.

Businesses can now write off the whole cost of their rainwater management system, and other sustainability projects, against their taxable profits.

Drier weather
Waterscan provides a comprehensive water management service including water auditing techniques.

Part of this service is the provision of a free rainwater management suitability survey. This would evaluate patterns of water usage on site, and suggest water conservation measures that can be introduced along with a suitable rainwater management system.

Such a system would be provided as a complete package including installation works. Central to the process is a range of Waterscan Aqua-Control units (see Table 1).

These are compact engineered packages with all main components housed in a single enclosure cabinet, including integral break tank, pumps, filtration, instrumentation, ancillary equipment and control system.

A Waterscan rainwater management system recommended for new builds incorporates an Aqua-Control 1000B controller with submersible pump suitable for use where tanks can be installed underground. The system delivers rainwater when available but reverts to mains potable water in drier weather or longer periods of drought when collected rainwater reserves are depleted.

The main advantages of this system are that a water supply to the building is guaranteed, while the use of rainwater is maximised.

With the Aqua-Control 1000B system, rainwater is collected from the roof of the building, and initially filtered using a mechanical self-cleaning filter. The filter is placed in-line on the top of the underground rainwater storage tanks, with the filter mesh located just under the maximum water level of the tank.

When the tank overflows, dirt is removed from the filter, improving the self-cleaning effect. Additionally, integral sprinklers rotate using pressurised rainwater to periodically scour the filter surface.

Using a submersible pump with a flexible floating extraction pipe, rainwater is pumped into the integrated 200-litre-capacity break tank within the Aqua-Control 1000B system enclosure cabinet. The control unit monitors the rainwater level in the underground holding tanks and in the integrated break tank.

Using the submersible pump, rainwater is transferred to the Aqua-Control unit on demand. The double self-priming booster pump set then transfers water to applications directly from the integrated tank.

The rainwater flow and mains water back-up supplies are fed into the top of the integrated break tank such that at least an AA-type air gap is maintained above the water surface in the tank in accordance with the BS EN 1717 standard.

When the level in the rainwater storage tanks reaches low level, solenoid valves switch the supply over to mains water. Additionally, the mains water solenoid valve is opened periodically to allow flow through supply pipes to prevent stagnation.

No interruption
The result is a system that provides rainwater when available but does not interrupt supply, switching to mains water when required. The added advantage of the small integral break tank is that when servicing of equipment is required it is only necessary to drain down 200 litres capacity, and not empty the whole contents of the rainwater storage tanks.

Also, when the large rainwater tank runs dry it is not necessary to fill this up with mains water, as only 200 litres is required to fill the integral break tank.

The Aqua-Control 1000E differs from the 1000B described above in that it is designed for tanks located above ground. Integral self-priming pumps can lift rainwater directly into supply from these rainwater tanks or take a supply from the integrated break tank which is fed with mains water as required.

The Aqua-Control 100-300 series units work in a similar way to the 1000E. These are used on smaller applications where lower demand exists and only a single-duty supply pump is required.

Water conservation
Waterscan was set up for the benefit of municipal and industrial customers to provide, in addition to rainwater management systems, water audit investigations, leak detection surveys and repair services.

Last summer, Waterscan was named one of the top 20 winners in the BT Business Essence of the Entrepreneur Award. More than 200 entries from across the UK were scrutinised; the winners had to demonstrate an entrepreneurial spirit, and show how they had used new technology to succeed in business.

The judges recognised Waterscan's ability to implement advanced technology to help their customers understand, monitor and reduce their water usage.

Commenting on the award, an Essence of the Entrepreneur judge said: "Water conservation is very topical at the moment. And it is great to see a small company helping the large corporations save water, money and the environment."

A revolutionary online database manages Waterscan's water audit projects by recording water invoices, monitoring consumption and targeting high users. The key to the system is instant communication between clients and Waterscan's engineers via email, text message or online reporting. The database currently supports more than 50,000 sites for Waterscan's clients, which include Tesco, Whitbread and BT Group.

The Waterscan system was conceived as part of the Green Technology Challenge launched by the government in 2001 for business investment in environmentally friendly technologies.

Part of the Waterscan system uses data loggers to remotely monitor water consumption. Recently, the PW2 Logger has been launched, which provides daily meter readings to ensure accurate billing. If a leak occurs, the device automatically sends a text message. And one of Waterscan's engineers is on site within 24 hours to rectify the problem.

The 20 small businesses that won the award represented a diverse range of industries. Finalists were selected by a panel of experts, including John Dunsmure, managing director of British Chambers of Commerce Enterprises; Andrew McGregor, head of marketing and strategy for BT Business; Gavin Dollin, head of Business Link National Partnerships; and David Lloyd, a key player in the leisure club market.

Installing a Waterscan rainwater management system incorporating an Aqua-Control unit is an effective way of reducing water consumption and costs. And it helps to manage rainwater run-off.

Using rainwater appropriately can save money on water bills, and, while reducing pressure on our environment, help conserve our valuable drinking water resources.

Neil Pendle is managing director at Waterscan.
T: 01243 839880.

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