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Go grey for green

Every day you flush hundreds of litres of reusable grey water down the drain – a simple grey water system can divert this water, allowing you to save potable water and money and have a green garden throughout the year!


By Gina Hartoog















Water that has been used for washing – whether in the bath, shower, basin or the washing machine – is called grey water. This water can be reused for garden irrigation. In some homes, grey water is plumbed back and reused to flush the toilet. Toilet water, called black water, should never be utilised.


There is currently no legislation in South Africa on the use of grey water, but if you are considering a system, you should check with your local authority as some municipalities may have their own by-laws. The average residential household of four people can save between 200L and 300L of grey water daily.


Why recycle grey water?

South Africa is a water-stressed country. Our average rainfall is around 492 millilitres per annum, about half of the global average. About 60% of water in South Africa is used in agriculture. In homes, most of our water usage goes to flushing toilets and taking a bath or shower. In households with gardens, over 45% of water usage goes to irrigation.


Reusing grey water in the home is just one of the ways you can choose a more sustainable lifestyle. It’s relatively easy to achieve and most systems are cost-effective to install. Your water costs will also decrease, as you are recycling water you would otherwise be pumping down the drain.


Marc Yoko, owner of Water Conservation Systems, says that South Africans should start taking water conservation seriously. “Many areas have continuous water restrictions, so it is essential that we conserve the water we have,” says Marc. “The population is growing at a rapid rate, which is putting further pressure on our already limited water supply. We can live without electricity, but we cannot live without water.”


Benefits of recycling grey water

Besides saving you money on municipal water usage, using grey water responsibly and correctly has numerous benefits. “You can have a green garden all year around,” says Marc. “It also enables gardens to flourish in areas where water may not otherwise be used for gardens.” You will also be able to water your garden during periods of drought or water restrictions. Grey water also contains certain nutrients like phosphorous and nitrogen, which can be beneficial to plants.


Grey water systems

The easiest way to utilise grey water in your garden is to manually use a bucket to remove the water from your bath or shower and use it to water the garden. All the same rules apply, including using biodegradable products.


As long as grey water is utilised responsibly and correctly, it is safe. “Most of the concerns about grey water are to do with the hygiene aspect and odours of the water, but both these aspects are eliminated if the water is reused as soon as possible and bacteria has not been given time to produce,” says Mike Bekink of Grey Water Systems. “The idea behind effective grey water management is to reuse the waste water within 24 hours, this eliminates the growth of bacteria in the water and ensures that the water is still pleasant smelling and hygienic. A small unit that uses the waste water as the bath or shower water flows through the drain is the ideal unit for townhouses, clusters and small developments.”

Waste water can also be collected in an underground tank. The water is then filtered and reused within 24 hours. A pump is then attached to an underground or above ground irrigation system, which directs water into the garden.


The last option is a central tank, which draws water from numerous units to one tank. “This means that each unit requires a collection tank and a pump to pump the water to the central tank,” explains Mike. “It is filtered and treated with an aerator and a biological additive, or with UV to sterilise the water. The water is then pumped through a time controlled system into an irrigation system. The only advantage of this system is that the watering times are controlled. Cost implications make this system more viable in larger developments.”


Choosing a system

Consider your needs and what the system has to offer before you make a final decision on a product. The system you choose will also be determined by the size of your garden and the number of people in your household. The system you choose must have an overflow pipe or valve, which enables you to divert water back into the sewer during periods of heavy rain, when harmful chemicals have been used in the water or during periods of illness. The system should also include a filter to remove solid waste like soap, lint and hair from the water before it is distributed.

Once you or an installer have installed your grey water system, make sure you understand how it works and what maintenance is required.


Guidelines for using grey water

  • Never store grey water for longer than 24 hours.  

  • Choose biodegradable and environmentally friendly personal hygiene and cleaning products (those used to clean the bath and basin) to prevent a build-up of salts in the soil.

  • Never reuse water from your kitchen sink or dishwasher.

  • If you wash cloth baby nappies in your washing machine, divert the water to the sewer. You should also do this when using chemicals like hair dye or bleach and if someone in the household is sick.

  • Allow grey water to cool in the tank before irrigating the garden. Hot water can kill off beneficial organisms in the soil.

  • Never allow anyone in your home, including pets, to drink grey water.

  • Grey water shouldn’t be allowed to pool on or run off paving – make sure it soaks directly into the soil.

  • Don’t overwater plants just because you have the water. If there has been a lot of rain, divert the grey water to the sewer.     

  • Maintain your system properly and clean the filters regularly.  

  • Don’t mix grey water with any harvested rainwater.  



Water Wise,

Water Conservation Systems,

Grey Water Systems,




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