Rainwater Recycling for Horticulture

Water storage tank catching rainwater from a tunnel roof

Even during the summer months, a surprising amount of water falls from the sky, providing a free resource that is unaffected by hosepipe bans or drought orders. Although there may be an initial infrastructure cost when installing a rainwater harvesting system, you can soon pay this back in reduced mains water charges.

Glasshouse roofs and metal framed buildings make an ideal rainwater catchment area, with a potential monthly yield, even in summer, of 60 litres of water for every square meter of roof catchment. A single 40m x 9m glasshouse roof could yield 21,000 litres of rainwater for recycling per month!

Rainwater Harvesting  Guide

Rainwater harvesting for nurseries & garden centres

We supply commercial rainwater harvesting systems for nurseries and garden centres. These normally use above ground steel sectional tanks, which provide a large rainwater storage capacity at a relatively modest cost. Where there are multiple roof areas for catchment, Access will provide advice on connecting the separate buildings to a single tank.

Harvesting costs and water security

In fact a covered storage tank can cost as little as £25-£35 per m3 of water stored. With mains water running at £1.50 per m3 in some areas, the tank and cover can pay for themselves in just 20 refills. Access Irrigation has many years experience in designing rainwater catchment and recycling systems.

In addition, rainwater harvesting provides independence from the mains drinking water system. As drinking water supplies come under more strain, DEFRA and water companies are already starting to consider prioritising how drinking water should be used. A DEFRA spokesperson was recently quoted as saying "Mains water is primarily for domestic users, and more mains water is made available for non-domestic [i.e. irrigation] purposes only if there is enough to go round."

Rainwater filterRainwater hygiene

Good general nursery practice can help ensure that the harvested rainwater stays as clean as possible, minimising any health & safety issues. So, you should aim to keep all roof catchment areas and gutters clean, and clear away any leaves regularly.

We can also include hygiene measures within the harvesting system. We'll supply pre-filters to ensure that any large debris (typically about 0.6mm) is filtered to drain before entering the tank. Water is normally calmed on entering the tank to ensure that any sediment is kept undisturbed.

We can also include overflow skimmers, to ensure that any small, light particles, such as pollen, are skimmed off the surface. And we suggest adding a lightproof cover to the tank.

If necessary, the rainwater can also be treated as it leaves the tanks, either by conventional filtration, slow sand filtration or by UV lights or chlorine systems.

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