Rainwater v’s Greywater – What is the difference?

Rainwater v’s greywater recycling for water reuse

Rainwater v’s Greywater – water comes in several different colours – and the terms can be confusing as different definitions apply depending on who has defined them. Here are some examples:

• Blue water – the water in our surface and groundwater reservoirs.
• Green water – either coastal waters or the use of rainwater in the soil.
• Brown water – navigable rivers and their estuaries.
• Grey Water – the water that becomes polluted during production

But things become clearer when referring to rainwater and greywater. They are not the same.

The difference between rainwater and greywater

 Rainwater is the water that drops down from the sky. It may pick up passing pollutants, pollen, and microbes in the air, on its journey down, but it is generally free from contaminants and almost pure.

When we collect the rainwater, the surface we collect from will also share organic materials and dust. Non-the-less, rainwater is clean, if not completely pure, and has a wide range of uses.

Greywater is household water that has been used once. It comes off washing machines, baths and showers, and bathroom sinks. Kitchen sinks are not included because this water has yet another colour – black. Blackwater often contains bacteria and other microbes from food preparation, and this water quality is usually more heavily contaminated.

The greywater can be used for irrigation – if the household uses greywater-safe products. These do not change the pH of the water, neither do they have high levels of salts and boron. If used with care, greywater can eke out water shortages.

How to use rainwater for irrigation

Rainwater, being clean, can be stored for longer periods than greywater. Particulates can be filtered out before entering the storage water tanks. The rainwater can be used on edible crops as well as potted plants and garden beds. Hand watering or drip irrigation lines may be employed.

Rainwater is also used for cleaning machinery, dust suppression and many other uses in agriculture, around the farms and in domestic gardens. It is just a matter of collecting it and storing it in the right rainwater tanks.

Can greywater be used for irrigation?

Since there are microbes in the water, greywater should be used within 24 hours to prevent multiplying – unless the water is filtered through a reed bed or professionally designed system. While it is not suitable for watering edible crops, it can be used to water fruit trees. Greywater can be released directly onto the land below the surface.

Greywater can be used in several ways in the industry, as well as flushing toilets in commercial premises through water management greywater recycling systems.

It is important to ensure the water is not kept over 24 hours, so an automatic pump is used to cycle the water out before it becomes “black water”. Greywater should be stored in the correct grey water tanks.

How do I irrigate with rainwater vs greywater?

Both rainwater and greywater are excellent ways to irrigate crops while conserving water – but the uses are not the same though they complement each other. Many commercial sites use both systems, conserving the rainwater for where cleaner water is required and using the greywater elsewhere. Both sources of water reuse help reduce mains water consumption.

Enduramaxx water tanks for storing rainwater and greywater

We have tanks that are suitable for above ground and below groundwater storage. Above the ground, our plastic water tanks can hold up to 90,000 litres of rainwater and below ground, up to 9,500 litres. These large plastic water tanks are ideal for rainwater harvesting systems and as a water supply storage tank for long term storage.

Our below ground tanks can be used for storing potable water or for irrigation and are made from high-density polyethene with smooth, hygienic surfaces. We can offer galvanised or plastic lids and various turret sizes. Rainwater filters to filter out moss, leaves and other debris are available. Underground tanks also need a pump to be incorporated.

Potable drinking water tanks and slimline water tanks are available for the storage of water. Our tanks come in various shapes, from the 800-litre water butt for the garden to the slimline tanks, useful where space is limited. These tanks are opaque, so you can see the water level remaining, and many are baffled, which reduces the movement of the water and adds strength.

All our above-ground water tanks are UV stabilised for many years of use, help promote environmentally friendly water storage systems and come with a ten-year guarantee. You can see our range of rainwater tanks here. For further information give us a ring on 01778 301527.

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