09/02/2018 14:40 GMT | Updated 09/02/2018 14:45 GMT

What Qualifies As Greywater?

This is what you need to know about greywater...


The water crisis in Western Cape has highlighted the role recycled greywater systems can play in saving water. Recent news has brought to prominence two low-cost greywater-recycling systems invented by locals: Retief Krige and the late Nkosinathi Nkomo.

But what exactly is "greywater"?

According to TheGreenAge and The Rain Harvest Here's what you need to know:

1. What is greywater?

It's the general term for bathtub, shower, sink or washing-machine water. Water from the kitchen sink after washing up may have a high fat content, so it can only be used in certain greywater applications – if you use it to water plants, it may damage them, for example.

It is advisable to use biodegradable products in the washing machine, so you can use that water on garden plants afterwards – the average suburban garden accounts for about 35 percent of domestic water consumption.

Most of the concerns about greywater are to do with hygiene and odours, but both are eliminated if the water is reused as soon as possible, and bacteria is not given the time to produce.

2. What are the advantages of using greywater?

It will lower your fresh water usage, put less strain on septic tanks, and is cost-effective – up to 80 percent of waste is reused. It can also have effective nutrients for plant life, and helps consumers avoid penalties during water restrictions.

3. What are the uses of greywater?

Flushing toilets:

Typically, about a third of household water is used for flushing the toilet, but reclaimed greywater used for this purpose saves valuable drinking water.

Watering plants:

It can be used in combination with an irrigation system to water the garden automatically. Targeting specific areas of your garden is a more environmentally friendly way to care for it than random sprinklers, so consider investing in a watering can.

Any organic material remaining in the water can be absorbed by the plants, but it is not recommended that you use greywater to irrigate homegrown vegetables.

Washing clothes:

Reclaimed shower, bathtub and bathroom sink water can also be used for washing clothes. As with flushing toilets using greywater, plumbing needs to be put in place to redirect the used water to the washtub.