Water Recycling for the Greenhouse

Whatever your take on the whole “climate change” debate, one thing is for sure – there are times when the British weather can be unpredictable to say the least and no aspect more so than rainfall. Despite the occasional floods of almost Biblical proportions over recent years, the successive droughts and hosepipe bans have underlined the point that water is something which we can often take rather too much for granted. So what can be done to help and what opportunities are there for recycling water in the greenhouse?

One of the most obvious ways to help reduce the demand for treated water is to collect your own rainwater – which is better for your plants in any case – and a little guttering and a rain-butt can fairly quickly have you capturing all the rain which falls on the greenhouse roof. There are many types of butts available – mostly made from plastic – ranging from the functional green versions to those which look for all the world like old wooden barrels and at prices to suit most pockets. For around £40, you can pick up a good 190 litre butt and stand, while if space is limited, the smaller 100 litre version is available for slightly less. One key feature to look out for is a child-proof lid to ensure that any small visitors to your garden stay safe.

A Grey Area

Another possibility which has been receiving increasing interest over the last few years is the re-use of so-called “grey” water – left-over from baths and showers for instance. Although, of course, it is possible to carry the water out to the greenhouse by bucket – and many have in times of drought – it is not exactly convenient and a number of ingenious methods to simplify things have been developed, ranging from the simple to the sophisticated.

Costing around £20, the “WaterGreen” siphon pump represents one of the best of the relatively low-tech approaches, allowing you to move grey water from the bath, shower or sink to the greenhouse very easily and simply. Driven by a few squeezes of its integral hand-pump unit to set up the siphon effect, it has a Hose-lock attachment to allow it to be linked to any standard hosepipe and it can then be left to get on with the job without the need for further supervision. Its makers claim it will empty a bath in minutes and – perhaps more importantly – that it can be used even during a hosepipe ban or drought order.

At the other end of the scale – with a price tag of around £200 for the unit alone or double that fully fitted – the “Aquastore Garden System” brings a surprising level of sophistication to the whole business of grey water recycling. An easily installed device, at its heart lies the proprietary “Alchemi” filter which cleans the water of both bacteria and soap, eliminating the usual difficulties of storing grey water for use at a later date. The company claim this system – which is based on sea water and activated carbon – can bring water back to within the limits set for European bathing beaches and apart from a yearly filter change, the only other maintenance it requires is the periodic cleaning out of the unit’s built-in hair trap.

Closing the Loop

Many commercial greenhouses take the whole concept one step further, effectively running closed systems, collecting the run-off from watering and recycling it many times over. It is possible to use a similar approach in the amateur greenhouse too, if the idea appeals, but with one or two important provisos. The main problem with direct recycling is the potential for disease causing organisms to spread rapidly, making some form of sterilisation essential.

Some people have adapted sand-filtration – a tried and tested method used extensively by commercial growers – to clean up the water, building small filter units for themselves. However, if the idea of developing a closed water system really does appeal, ultra-violet disinfection would probably be an easier route to follow, especially since suitable UV systems are now so widely available for use in ponds and water-gardens. Closed system recycling is certainly not for everyone, but for the enthusiastic adherent, it can add a new dimension to the greenhouse.

Reducing the amount of fresh, treated water we use in our greenhouses makes obvious sense, environmentally and – if you have a water meter – economically too. Irrespective of our individual motives – keeping to “green” principles, getting around a hosepipe ban or simply reducing the water bill – the opportunities are clearly there and the good news is that it is not necessary to spend a small fortune or put yourself out unduly to benefit from them.