Greywater Systems for Homes

South Africans use roughly 237 litres of water per person per day — well above the global average of around 173 litres. A meaningful share of that goes down the drain as greywater: water from basins, showers, baths, and laundry that is lightly soiled and, with the right handling, perfectly usable again. Given that Johannesburg Water’s own figures show 44.8% of the city’s water is lost before it even reaches a tap, rethinking how you use the water that does reach your home makes practical sense.

This article explains what greywater systems actually do, what different setups cost, and what rules apply to Johannesburg households.

What counts as greywater — and what doesn’t

Greywater is wastewater from sinks, hand basins, showers, baths, and washing machines. It is distinct from blackwater, which comes from toilets and kitchen sinks (the latter contains food residue and pathogens that make treatment far more complex).

The distinction matters because greywater is recoverable with relatively modest treatment, whereas blackwater requires a full sewage-treatment process. Most home systems deal only with greywater from the bathroom and laundry — kitchen sink water is usually excluded for practical reasons even where not legally required.

The main types of greywater system

Simple diverter systems redirect untreated laundry or shower water directly to subsurface garden irrigation. These are the cheapest option and require no electricity, but they must be used carefully: untreated greywater cannot be stored for more than 24 hours, must not contact edible parts of plants, and should not pond on the surface. As a rough guide, basic diverter kits and installation typically start somewhere in the low thousands of rand, though you should confirm exact pricing through quotes.

Filtration and disinfection systems pass greywater through physical filters and a UV or chlorine stage before storage and reuse. These allow storage of treated water for longer periods and open up uses such as toilet flushing. Expect meaningfully higher costs than a simple diverter — system complexity, tank size, and pump requirements all vary, so quotes are the only reliable way to scope your budget.

Integrated whole-home systems combine greywater recycling with rainwater harvesting and sometimes borehole input. These are engineered installations rather than DIY products, and costs can overlap with the R40,000–R150,000 range associated with borehole installations, depending on scope.

How much can a greywater system actually save?

Honestly, this depends entirely on household size, water usage habits, and what you redirect the recovered water towards. Toilet flushing and garden irrigation together account for a significant portion of household water use, so targeting those applications gives you the best return. However, be cautious about headline saving claims from installers — ask to see the assumptions behind any figures quoted to you.

What greywater systems do reliably is reduce your dependence on municipal supply for non-potable uses, which matters given that Johannesburg’s reservoir system holds roughly 27 hours of citywide storage buffer. That buffer is thin, and any reduction in demand on potable supply during a disruption is genuinely useful. You can read more about the broader picture of household water resilience on our water solutions blog.

Rules and compliance in Johannesburg

Greywater reuse in South Africa is regulated at both national and municipal level. The key points for Johannesburg homeowners are:

• The City of Joburg permits greywater reuse under specific conditions. Check current guidelines directly with the City at joburg.org.za, as rules can be updated.
• Greywater may not be discharged into stormwater systems or onto public land.
• Untreated greywater must not be sprayed above ground (spray irrigation is not permitted for untreated water — subsurface drip is the accepted method).
• Treated greywater intended for toilet cistern use must meet quality thresholds aligned with SANS 241 (2024 edition) for the relevant water quality class.
• Any plumbing work connecting a greywater system to your household supply must be done by a registered plumber; cross-connection with potable water pipes is prohibited.

Non-compliance can result in an order to decommission your system at your own cost, so getting the design right from the start matters.

Installing a greywater system that actually meets Joburg's requirements starts with finding an installer who knows the local rules. Compare 3 free quotes — vetted installers, no obligation.

Choosing the right system for your property

A few practical questions will narrow your options significantly:

Question	Why it matters
How large is your garden and what are you irrigating?	Determines how much recovered water you can usefully apply
Do you want toilet flushing as well as irrigation?	Requires a treated, stored system — not a simple diverter
Is your property on a slope?	Gravity-fed systems are simpler and cheaper where feasible
How old is your plumbing?	Older systems may need upgrades before greywater can be integrated
Do you rent or own?	Landlord consent and lease terms affect what modifications are permissible

A reputable installer will assess your site before quoting. Be wary of any quote provided without a site visit — system sizing without understanding your property’s layout is guesswork.

Detergents, cleaning products, and water quality

One thing many homeowners overlook: the quality of greywater is directly affected by what goes into the drains in the first place. High-phosphate detergents, bleach, and antibacterial products can damage soil structure and harm plants when applied repeatedly through irrigation. If you intend to use a greywater system, switching to plant-compatible, low-sodium, biodegradable cleaning products is sensible — and relatively straightforward. This is also relevant to the water-saving habits covered in our guide to saving water at home, where product choices sit alongside behaviour changes as practical low-cost steps.

Greywater vs other backup water options

Greywater systems reduce potable consumption but do not provide a supply of drinking water. If your concern is supply interruption rather than conservation, a backup tank-and-pump system (typically R20,000–R40,000, with whole-house examples around R55,000) or a borehole (typically R60,000–R100,000 for most Johannesburg installations) addresses a different problem. Many households end up with a combination — a greywater system for ongoing conservation and a storage or borehole solution for interruption resilience.

Neither approach is universally right. The best solution depends on your specific water use patterns, budget, property constraints, and how you weight ongoing savings against upfront cost.

Not sure whether a greywater system, storage tank, or borehole makes more sense for your situation? Get free quotes from qualified installers and compare your options side by side.

Getting the installation done properly

The greywater system market includes a wide range of suppliers, from specialist water-solutions companies to general plumbers adding it as an extra service. Quality of design and installation varies considerably. Ask any installer for proof of plumbing registration, references from previous greywater installations specifically, and a written explanation of how their design meets City of Joburg compliance requirements. A system installed without proper compliance documentation is a liability, not an asset, when you sell the property.