From grey to black: innovation for greywater

By: Fiona Ingham – writer

Building contractor Danie Groenewald has spent decades working in the townships of North West and knows their congested, dusty streets like the back of his weathered hand. It was here that he came up with a simple water-saving device, arising from the notion that using potable water for toilets is not sustainable.

South African townships largely comprise high concentrations of informal housing and shacks, connected by potholed roads, with poor power, water and road infrastructure. Traditionally, water pressure has been low, with sparse amounts available to each household. But since 1994, the government is raising living standards – shacks are slowly being replaced by government-subsidised houses, roads are being tarred and repaired and the basic services are slowly being put in place. The aim of government is to provide each home with a flushing toilet, but this also naturally means adding to the wastewater of an already overloaded, dysfunctional system.

While involved in the building of state-sponsored housing Groenewald saw how the women in households, most often grandmothers, wash the families’ clothing outside in yards, where the garments can be seen flapping on lines that criss-cross the yards.

In amid the rows of houses, concrete corrugated wash troughs are a familiar sight, but these are rough on hands and even rougher on clothing. Householders tend not to use the troughs, but carry water from taps in plastic or metal tubs or buckets and place them on chairs or tables. By washing outside, the women are free to chat to neighbours and passers-by, which is what makes these communities such sociable places.

This greywater is then thrown out into the scrubby yards and is lost. Although this is a low volume of greywater lost compared to that which washing machines lose in higher-income neighbourhoods, Groenewald believed he could provide an alternative and invented a simple water-saving system compatible with outside wash troughs.

Flushing with greywater
The invention is simple: a 45ℓ plastic wash trough, which is an alternative to the concrete trough and portable wash tub, attached directly to a purpose-made plastic container or holding tank, fitted against the outside wall of house and attached to an inside toilet in the same way a cistern is attached to a toilet. The difference is that the householder now washes clothing more comfortably, standing upright and uses the tap above the trough. When the plug is pulled, the water collects in the holding tank, ready for use to flush the toilet. The container has a capacity for 130ℓ of greywater, which will flush one toilet 14 times a day.

“In 2009 I fitted my first unit in a household of three people,” Groenewald says. This pilot model was fitted at the Letshewenyo residence in Joubertson and soon the results were evident. In a City of Matlosana bill addressed to BT Letshwenyo dated 17 October 2009, the water consumption was reflected as 11 000ℓ or 366ℓ a day. In the second bill dated 21 November 2009, after fitting the system, the consumption is reflected as 7 000ℓ or 233ℓ, or a 133ℓ a day saving.

The householder herself provided proof of the savings. In a June 2011 letter addressed to him, Cathrine Letshewenyo wrote that “Mr Groenewald of New Ideas has installed a ‘Wash o Toi’ to my house since 2009. I can flush my toilet with already used water. The system has never broken and we are saving a lot of water. Before we paid about R32 a month for water and now we pay about R5,” she writes. In households with a low income, this can make all the difference.

This early success proved to Groenewald that his system was worthwhile. “I have worked for seven years full time on this,” says Groenewald. “I have sent emails to each municipality and to mayors and I have visited towns.” He said the officials have been hesitant to act, despite its obvious benefits. “For seven years I have been trying to get someone’s attention – for decision-makers to see that this invention is working.” The pilot project in North West now involves 418 households which have been operating since then, he says.

Groenewald says years ago, when Toyko Sexwale was minister of water affairs, his invention caught his attention at a water convention held in Sandton. “The minister told me he would give me five minutes to explain my invention, but he spent about 25 minutes with me. He then came back to me with his entourage and told me ‘This is simplicity becoming efficiency’.”

Large-sale water savings
Seen on a larger scale, if the system were to be installed at 1 000 government-sponsored homes, roughly 4 million litres of potable water, that would have been used to flush toilets, can be saved. The system has many other positive spin offs, as toilets can also be flushed during water cuts.

Patented, trademarked system
To install the system at a new home and to retrofit it on an existing system costs about R3 000. “Our system replaces only the cistern of the toilet. The advantage of this is that a skilled person can be taught how to install these in just a few hours. It uses the same flush mechanism of a normal cistern and will need the same maintenance as a cistern does in future,” Groenewald says. “If it is broken, it can be fixed with a wire.”

PA WashoToi Body

NEP Consulting Engineers supports the invention. “I can confidently recommend the installation of the system as a guaranteed method to flush toilets with greywater,” wrote PE Ernst in 2011.

Groenewald says no other similar system exists on the market. He has patented and trademarked the Wash-o-Toi and is excited about the myriad advantages the system offers. “Even when the water supply is cut off, residents will be able to flush toilets. This is not just a short term or medium solution – it is a permanent solution to using potable water in toilets.” He continues: “There can be no defendable reason why this unit cannot be installed in new and existing houses throughout South Africa. Training unskilled labourers to do this will also create thousands of jobs.”

Not only for subsidised homes
Groenewald’s simple, cheap solution to use greywater more effectively can be applied across the board, across all income levels. The volume of greywater wasted in townships is modest, when compared to that consumed by suburban washing machines that use up to 150ℓ per load, depending on the machine’s efficiency. An adapted system can also be installed in suburban households, where shower and bathwater collects in an underground trough and is then pumped up to the cistern. This adapted system costs about R5 000 to install.

He says that according to a government’s own 2009 survey, which has not been updated, a typical household in a state-subsidised home uses about 160ℓ of clean drinking water each day to flush toilets. If this system is implemented at 1 000 state-sponsored homes, close to 5 million litres of potable water can be saved each month. In a country that regularly suffers devastating droughts, it’s a system worth implementing.

Recycling is part of North West government policy
According to North West housing Draft New Homes Policy Standard Specifications for Housing Projects, the standards are as follows: 
• The minimum area of the house must be 45m2.
• Must have two bedrooms, kitchen and living/dining area.
• Bath, handbasin and toilet and internal water recyling system.
• Smooth internal floor finish.

*Photo credit: Johann Venter.

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