Rainwater Harvesting

  • How it Works

    Water is a valuable commodity, and as a whole we must improve the way in which we use it and conserve its supply whenever possible. With improved plumbing system design, and the move away from baths to showers, use of low quantity flush sanitary appliances, and water saving taps being a priority in all new homes.

    Rainwater harvesting is the term given to the collection, storage and distribution of rainwater which falls onto our buildings roofs.

    The highest quality water we require within our homes and places of work is that of drinking water, also known as "potable water". Potable water supplied to our homes via the water mains infrastructure and ultimately from our reservoirs is expensive to produce and becoming scarcer. I think most people over the age of 20 can recall summer droughts and water restrictions, yet we waste in the region of 60% of this top quality potable water in areas that don't require it. Flushing toilets, washing machine use, car washing, and light garden watering consume 60% of our total water intake.

    Harvesting rainwater makes both environmental and economic sense, after all rainwater is free! and every litre harvested is a litre that does not go through the water meter saving money.

    If all new homes were fitted with a rainwater harvesting system, it would benefit the community as a whole, huge amounts of energy would be saved, thus reducing the cost of water purification, reservoirs would not require extending and the environmental impact would be reduced. Also, less chemicals would be needed and the risk of flash flooding and storm water management would be reduced.

    On a commercial basis large stores of harvested water can be used to great advantage in hotels, schools, laundry's, factories and any number of other commercial activities that use large amounts of non potable water. For one large hotel we have designed a system that actually produces the majority of its domestic hot water by extracting the latent energy entrained within the harvested water before its used within the hotel, see commercial section on this site.

    The rainwater that falls onto our roofs is generally a soft water, thus it is easier on appliances and upon the environment. Having little or no calcium, plumbing valves do not clog up and it has causes little or no corrosion to brass and copper plumbing pipes and fittings.    

    Rainwater harvesting technology is relatively simple. The rain that falls onto the roof is collected by the gutters and is channeled to a harvesting tank, usually underground, but not essentially so. All debris and leaves are automatically filtered out by a simple not mechanical backwash system in the tank, allowing only the clean water to enter the tank.

    Within the tank is a floating suction line that is set about 300mm (12") above the base of the tank, this allows for the fine sediments to settle to the bottom and stored water to be drawn off without the risk of stirring up the fines at the base of the tank. The water enters the small water booster tank, this is usually located in a nearby garden shed or the garage, and from here is pushed under pressure from the pump into the building by a network of dedicated water pipes that supply the toilets, washing machine and garden taps.

    The booster tank also has a small independent mains water fed reservoir,  just in case during sustained drought periods the harvesting water runs out of stored water. A simple float within the main harvesting tank signals the booster that the water is low and automatically the mains water fed top-up tank is brought into operation until the float assemble tells the booster tank that after rainfall normal conditions have returned.

    There is no limit to the capacity of the harvesting system and commercial installations stand to make huge savings typically due to the larger catchment areas available and the greater demand for water.

    If you would like more information or a quotation for a specific project please contact us.

  • Rainwater Harvesting Tanks & Installation

    Rainwater Harvesting Systems are available from us to fulfil any application from the smallest residential system to large commercial application's. We have designed and supplied many installations for domestic and commercial installations. The most popular model for light domestic use is the L-3000 model installation with a 3000 litre below ground harvesting tank with a L-CRV-DS/BGM7 pressure booster system.

    Technical Details on L-3000 System package

    The equipment package consists of the following;

    1. Maxi-Rain 3000 Polyester Rain Water harvesting Tank Code UK2203000

    Stainless Steel Suction Strainer, Self Cleaning Suction Filter, Anti-siphon Trap, Fixing Straps, Stainless Steel Anti Rodent System, Bolt on Lid, System Connections.

    2. Tank Dimensions

    Model 3000

    Diameter 1430mm Height 2419mm Weight 213 Kg
    3 – Tank Connections
    1 x 110mm Duct for float
    1 x 50mm Duct (c/w draw string)
    1 x 110mm Rainwater inlet connection
    1 x 110mm Water Overflow Outlet to soakaway
    1 x 110mm Water Outlet from the lead screen to soakaway
    4. Pump Package

    The Lowara Pump Package Model CPV-DS/BGM7 Code UK2205700 is supplied complete with control equipment and float assembly, Automatic change over valve in the event of lack of rain water and two suction lines.

    Pump Dimensions
    900mm High x300mm Deep x730mm Long Weight 23 Kg

    Plumbing Connections ¾”
    Power Supply 240v Single Phase 1.11 Kw motor, 5Amp Fused
    5 . Duct requirements (by others on site)

    1 off 110mm Osma duct from the pump location to the Rainwater Harvesting Tank
    1 off 50mm Duct (as above
    L-3000 Harvesting Tank awaiting installation

    Correct installation of the harvesting tank is critical, if the following instructions are deviated from in any way the warranty may be compromised.

    Harvesting Tank - Embedded Tank Installation Instructions.

    Tank installation is to undertaken as follows,

    1. Ensure the tank is sealed from foreign debris entering during installation.

    2. To avoid any lateral forces being exerted upon the tank it should be located outside of a 45 degree angle  of the base of any nearby foundations.

    3. Ideally the tank should be within 12 metres of the harvesting pump station.

    4. The excavation works should allow for a 200mm bed of lean mix concrete with one layer of embedded A98 steel mesh.

    5. Steel loops (4 off) should be hooked into the A98 mesh and be proud of the tanks base 1/3rd in from either end, this will provide a fixing point for the tank restraining straps.

    6. 150mm of sloppy weak mix cement should be poured directly on top of the base slab just prior to installation.

    7. The tank should be carefully lowered into the hole and gently bedded onto the weak cement slurry mix.

    8. Fixation straps should be fixed to the four (4) steel hooks and loosely tensioned.

    9. Fill the tank 2/3rdfull with water, tension the restraining straps and backfill with lean mix concrete, compact each 300mm layer gently

    by hand. Ensure the concrete infill is compacted evenly on all sides.

    10. Fill the tank to the overflow level and continue to backfill and compact in an even manner upto the overflow level.

    11. Connect the overflow run off pipe to the 110mm pvc connection.

    12. Extend the 110mm overflow in solid plastic to the energy probe & onwards to soak away.

    13. Install the tank access lid and cover.

    14. Extend 50mm electrical / sensor duct c/w drawstring from tank to pump station.

    15. Install 110mm service duct from tank to pump station

    16 - Backfill the remaining area with top soil.

    15. Leave the water in the tank until commissioning.

    Other Below Ground Harvesting Tanks in the Range 

    Below Ground Domestic Harvesting Range

    L4000 System
    L5000 System
    L-6000 System

    Booster Pump Options

    1. L-CPV-DS/BGM7
    2. L-CPV-DS/BGM11

    For all aplications either Commercial or Domestic Please Contact Us.

  • Local Installations

    We have a number of installations large and small completed, this section of the web site is currently being upgraded to include the latest news and information, work on this area of the site should be completed by early November 2008.

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