Rainwater harvesting systems tend to be pumped, causing people to ask the following questions :

1. "Does the cost of running the pump negate any savings made?"

2. "By running a pump, are we increasing our carbon emissions, and negating any environmental benefits?"

Well, to answer those questions:

1. It typically takes 1.5- 2.0 kWh to pump 1 cubic meter of water (1,000 litres). For a typical house using rainwater for WCs, washing machine and the garden, pumping costs are between 5-10p per week. To put that into context, the supply and waste water charges associated with 1 cubic metre are in the region of £2.50. A net gain of around £2.40 per cubic metre.

2). It takes around 5kWh of electricity to supply 1 cubic metre of water (this of course is used by your water authority), but harvested rainwater uses around 0.5kwh per cubic metre.

So, in essence, it is both financially and environmentally beneficial to install rainwater harvesting.

Photo by Photos8.com

About the author: Barry Nutley is co-founder and director of Viridis Energie Consultants

About the author: Barry Nutley is co-founder and director of Viridis Energie Consultants

If you have a question about anything in the above blog, please ask it in the comments section below.