Why Use Greywater for Irrigation?

It’s a waste to irrigate with great quantities of drinking water when plants would thrive on used water containing small bits of organic matter.

greywater irrigation

Grey water irrigation on White River Country Estate

Unlike a lot of ecological stopgap measures, greywater use is a part of the fundamental solution to many ecological problems and will probably remain essentially unchanged in the distant future. The benefits of greywater recycling include:

Lower fresh water use Greywater can replace fresh water in many instances, saving money and increasing the effective water supply in regions where irrigation is needed. Residential water use is almost evenly split between indoor and outdoor. All except toilet water could be recycled outdoors, achieving the same result with significantly less water diverted from nature.

Less strain on septic tank or treatment plant Greywater use greatly extends the useful life and capacity of septic systems. For municipal treatment systems, decreased water flow generally means higher treatment effectiveness and lower costs.

Highly effective purification Greywater is purified to a spectacularly high degree in the upper, most biologically active region of the soil (Center for Study of Federalism 1972). This protects the quality of natural surface and ground waters.

Site unsuitable for a septic tank For sites with slow soil percolation or other problems, greywater use may be a good alternative to a very costly, over-engineered system.

Less energy and chemical use Less energy and chemicals are used due to the reduced amount of both freshwater and wastewater that needs pumping and treatment. For those providing their own water or electricity, the advantage of a reduced burden on the infrastructure is felt directly. Also, treating your wastewater in the soil under your own fruit trees definitely encourages you to dump less toxic chemicals down in the drain.

Groundwater recharge Greywater application in excess of plant needs recharges groundwater.

Plant growth Greywater enables a landscape to flourish where water may not otherwise be available to support much plant growth.

Reclamation of otherwise wasted nutrients Loss of nutrients through wastewater disposal in rivers or oceans is a subtle, but highly significant, form of erosion. Reclaiming nutrients in greywater helps to maintain the fertility of the land.

Increased awareness of and sensitivity to natural cycles Greywater use yields the satisfaction of taking responsibility for the wise husbandry of an important resource.

Just because Greywater is relatively harmless and great fun to experiment with. Moreover, life with alternative waste treatment can be less expensive and more interesting.


Much fuss has been made over the potential health risk of greywater use, without comparison with the actual risk of the current practice of disposing of sewage into natural waters used for swimming, drinking and fishing. This questionable practice short circuits effective natural purification in soil and is considered one of the least desirable techniques by the World Health Organization (Wagner and Laniox 1958).

Approximately 20% of all U.S. communities still dump sewage in natural waters after primary treatment (solids removal) only. After heavy rains, even the most technologically advanced secondary treatment plants are forced to abandon all pretense of treatment and let raw sewage flood into the ocean or river.

Widespread greywater use in a population mostly unaccustomed to taking responsibility for utilizing natural systems would not be 100% risk-free. However, even with the inevitable misuses, greywater recycling as described here is safe compared to other common activities, such as kissing, dogs pooping on lawns, and swimming downstream of municipal sewers.

Source: Excerpts from agroforestry.net

Grey water is a wasted resource; the benefits of using gray water are undeniable.  Even if you don’t use municipal services, why not put your daily grey water to a good use instead of overloading your septic tank or French drain?  The environmental benefits, as outlined above, are substantial.  It is surprising that there is such minimal awareness and misinformation about grey water when we are living in an era where water conservation should be a top priority for individuals, businesses and governments.  South Africa is a water-stressed country and the situation will get worse.   If you do not have a garden/lawn then grey water can be recycled and used for toilet flushing; see the product demo to see how our Second Movement system and other products work. An earlier post contains a slide show of a greywater system installation.

In summary, grey water is great for garden irrigation and should rather be used in this way than letting it enter sewers and waterways.  By doing this, you will be saving water and protecting the environment.

Contact Water Rhapsody Mpumalanga/Limpopo for all your water conservation solutions in the Lowveld.  If you live elsewhere in Southern Africa, see our Locate a Dealer page. Residents and businesses living in southern Mozambique (in and around Maputo) are also invited to contact us.

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