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Collum & Gregg Ltd supply and fit both Gravity Fed & Pumped Retro Fit Urban Rain Harvesting system to Domestic and Light Commercial building. We Supply & Fit tanks, filters, pumps and accessories specifically designed for above ground rainwater collection and utilisation systems that can be installed in a confined space. The products are ideally suited for installation on domestic and light commercial property particularly as a retrofit solution. Collum & Gregg takes pride on our ability to offer customers;

  • Proven and easy to apply products
  • A comprehensive range of compatible products and accessories
  • Reliable service
  • Affordable prices


The Super-Slim Rainwater Tank is the narrowest wall mounted tank available and its unique design makes it visually discreet and easy to install. Multiple tanks can be joined together to achieve the desired storage capacity. It is affordably priced and easy to integrate into a wide range of above ground urban rainwater collection and utilisation systems. The Super-Slim Rainwater Tank offers the following benefits compared with conventional rainwater storage solutions.

  • Super-Slim tank, each 180 x 72 x 19cm that contains approximately 220 litres of rainwater.
  • Modular design, for either single or multiple tank installation.
  • Visually discreet, slim profile making it ideal for installation along side walls and narrow passages.
  • Proven and reliable, installed and tested since 2002.

See pics

Aboveground Rainwater Harvesting System. The package comprises of 2 main components. Ideal for external use by having a Tap fitted to the tank for using the harvested water in the garden.


The filter removes leaf litter and debris from the rainwater before diverting it to a tank. It also incorporates an inspection flap for easy access and maintenance and a backflow prevention feature to ensure foul water from the drain cannot enter the tank. Depending upon the system layout the filter can also act as the tank overflow. The filter is a high grade stainless mesh enclosed in a UV protected ABS plastic.


Tank modules can be connected together side by side to provide the storage capacity required. They are purpose made of food grade polyethylene for storage of rainwater to be used inside a property. The tank is of a heavy duty patented construction with added UV protection and is opaque to protect the quality of stored water.

See pics

Click here for PUMPED FED information


Rainwater Utilisation

A rainwater utilisation system comprises of a filter, storage tank, pump and mains valve that is connected to services and appliances to use rainwater for toilet flushing, laundry and garden irrigation. Rain falling on the roof of a building is channeled via the existing gutters and down pipe to a filter which removes leaf litter and other debris before diverting the water into a storage tank. When an appliance demands water a pump is automatically activated and draws water from the tank. In the event that there is insufficient rainfall to meet demand a mains water valve is automatically opened to partly refill the tank. At Collum & Gregg we believe that rainwater utilisation should be a practical and affordable conservation measure for all buildings. Conventional rainwater harvesting systems are complex and expensive to install and maintain, because the tank, filter and pump are installed below ground. Modern and visually discreet above ground systems enable owners of smaller property and those with limited space to economically reduce their use of mains water.

Urban Systems

Above ground rainwater utilisation systems for the urban 'built up' environment are a new innovation in the Ireland but are widely used in other countries. These state-of-the-art modular systems are an attractive, practical and contemporary solution to managing water resources and blend seamlessly with modern and traditional building designs. Urban systems that offer a modular tank design enable flexible sizing of the water storage capacity. At Collum & Gregg we make no excuse that urban systems can sometimes be a compromise between space, utility and cost. As much as 80% of the potential saving of mains water usage can be gained from an urban system at a fraction of the installed cost of a conventional below ground system.

Lack of Water

Water is becoming an increasingly precious natural resource. Whilst we appear to have an abundant water supply, 97% of the 1.4 billion cubic kilometres of water on Earth is sea-water, 2.7% of the remaining 3% is permanently bound up in ice at the poles. This leaves only 0.3% of the Earth's water resources as usable fresh water. It is now recognised that periods where we have a shortage of water in our reservoir can be limited by the use of domestic & commercial rain harvesting reducing the supply and increasing demand we have at present, Water prices will come into effect with the installation of new water meters. In Germany, the use of rainwater utilisation is over 100 times that of the UK & Ireland.

The Collum & Gregg Product list:

Cavity Wall and Attic Insulation

Aluminium/uPVC Fasica Soffit & Gutters

Roller Shutter Garage doors

Carbon Monoxide Detectors

Gutter Hedgehog

Rain Harvesting

Collum & Gregg are NSAI Agrément Certificate (No. 05/0191 & Registration Number IAB/0191/180) & are also registered (ID Nr 10622) with the SEI to carry out work on the HES scheme.


SEI information & grant application form


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