RAINWATER HARVESTING

SEL Environmental Ltd offer rainwater harvesting systems for domestic and commercial applications.

Domestic Rainwater Harvesting

Domestic rainwater harvesting systems can vary from a water butt used to water the garden to something more sophisticated requiring above or below ground storage, filters, pumps and header tanks. These systems will water your garden but will also provide a rainwater supply to wash your car, supply toilet cisterns and washing machines.

These systems can be divided into two types; Header Tank Systems and Direct Pump Systems.

Header Tank Systems
As the name suggests, require a header tank to be installed in the roof space or high-level space in the home. They have a high reliability and can easily revert to mains supply if the supply of stored rainwater runs dry. The controls are simple and inexpensive. However the water pressure from a header tank may be too low for some modern washing machines and toilet cisterns may take a while to refill.

Direct Pump Systems
These systems do not require a header tank and generate a higher water pressure making them suitable for washing machines which require a direct mains feed. Whilst these systems do not require a header tank they do require a booster pump set.

SKELETANK - for more information visit www.skeletank.com

To remove the cloak of specialism from rainwater harvesting systems, SEL Environmental Ltd have teamed up with Skeletank to develop a very simple and safe rainwater harvesting system that a competent DIY'er can install.

The Skeletank in a new type of rainwater storage tank with a high strength skeleton. It can withstand a load of 70tonnes / m2 and it is this high strength skeleton that allows Skeletank to be installed at very shallow depths. A normal skeletank rainwater harvesting system is less than 500mm deep from finished surface levels making it very safe for the installer. There are no deep excavations and therefore no requirements for large excavation plant or large volumes of soil and clay to remove.

It can be installed directly below a driveway and you can lay concrete blocks, slabs, and even tarmacadam over it.

Land Rover Freelander parked directly on to 4 skeletank units. A Freelander weighs from 1775kg, you may note the Freelander is 300mm off the ground.

The skeletank units are linked together using the standard 110mm diameter drainage connection which fits standard underground drainage pipe and the pipework connects to a 500mm diameter chamber which contains a pump. The pump we recommend has internal pressure controls (eliminating the need for external pump controls in the home) which turn the pump on when there is a demand for the stored rainwater e.g. when a tap is opened or a toilet is flushed. This will deliver the harvested rainwater until demand ceases e.g. the tap is closed or the header tank has refilled.

A skeletank unit only weighs 35kg and can be easily carried by 2 people. It will fit through a standard doorway which is ideal for restricted access e.g. terrace houses.

The skeletank unit has a 300litre capacity, so multiple units can be added together to suit your rainwater harvesting storage volume requirement.

SEL are currently developing a rainwater harvesting starter kit which will be a great benefit to the first time rain harvester. The starter pack will contain the basic essentials to provide a complete set of materials for someone to be able to install the minimum rainwater harvesting system. The starter kit will contain the following elements:-

- 3no. skeletank units providing 900litres of rainwater storage capacity
- 1no. 500mm diameter pump sump and pump
- 1no. 315mm diameter rainwater downpipe filter chamber
- 110mm diameter drainage pipework and fittings
- 32mm diameter black and green coded rainwater re-use pipework
- Outside tap kit

The kit will allow the user to install the most basic rainwater harvesting system comprising and an outside tap. Further components can be added to this starter kit to increase the rainwater storage volume and provide an indoor storage and supply as outlined above. The system is ideal for home use or even in remote locations as photovoltaic panels can be used to generate the power to drive the pumping and water management system that ensure that the system is topped up by mains water. This is an ideal set-up for watering animals.


Below are a selection of photos showing a typical skeletank installation.

Shallow excavation, normally less than 500mm deep	Levelled stone bedding layer
Skeletank units laid on bedding and checked for level	Standard 110mm diameter pipework connections
Skeletank units backfilled, a geotextile is supplied to prevent stone entering into the Skeletank units	Completed backfilling ready to paved over. This area will become a drive for off road car parking
500mm diameter pump chamber with pump in place in the smaller internal chamber	Inline back inlet rainwater downpipe filter chamber
Typical header tank installation	Typical booster set

More information on the skeletank system can be found at - www.skeletank.com