Grey water is an underutilised resource but, because of the water crisis, many homeowners are now looking into it.
According to Mike, there are more sophisticated systems that will get rid of odours. They cost around R120 000 to install.But what is a grey water system, how much does it cost, can it be retrofitted and is it legal to use?
With all of these questions, it’s important to educate yourself on the safe use of grey water. Here’s what you need to know…
1. What is grey water?
Will van der Merwe from Wett, Water eco technologies and treatment, says technically, all water that is not potable is referred to as grey water, whether it’s rainwater, untreated borehole water or waste water from a shower.
However, he says since there is a need to distinguish between the different sources of such water, we typically refer to waste water from baths, showers, hand wash basins and washing machines as grey water.
Will says thus, generally, the understanding is that grey water comes from these sources. He says waste water from a kitchen sink and dishwasher is not grey water, but is considered raw sewage.
According to Mark Joubert, from Garden ResQ, grey water is non-potable water emanating from the shower, bath, basin and laundry. This is not toilet or urinal water which is referred to as black water.
2. What can you use grey water for?
Mike Bekink, from Grey Water Systems, says you can use grey water for irrigating the garden and flushing toilets.
According to Will, depending on the sophistication of the treatment process, the water can be used in its most basic form for very basic irrigation via hosepipe and lawn sprinkler.
He says when treated properly, the water can be reused for toilet flushing, laundry and swimming pool top up. Be clear though, that the latter only refers to a very sophisticated and expensive system. The majority of the systems on the market can’t achieve this, he says.
3. Is grey water use legal?
Will says grey water reuse is legal, however, there are risks involved, and the reuse thereof has to be managed and implemented correctly.
He says incorrect ways of reuse and plumbing could be illegal. The authorities also have huge challenges with blocked sewer lines due to the large extraction of grey water from the system by end users.
When planning your grey water reuse, it’s wise to be strategic and divert some of the grey water to the sewer.
According to Mark, grey water use is legal in most towns and cities. However, he says some municipalities like Beaufort West do not encourage grey water reuse as they need all the water back to be in a position to filter, sterilise and treat so that they can feed it back into the system as potable water.
Will says grey water reuse is legal, however, there are risks involved, and the reuse thereof has to be managed and implemented correctly.4. How much does a grey water system cost?
Will says in its most basic form, where simple diversion of water is concerned, a system installed by a professional could cost between R12 000 to R20 000, depending on site-specific complexities.
Intermediate grey water treatment and storage for irrigation via conventional irrigation could be installed for between R50 000 to R100 000, depending on the volume of water involved and site-specific details.
According to Will, a sophisticated system which will treat the water to a standard where it is free of all contaminants and bacteria, and is clear as tap water can be installed for R90 000-plus at a household level.
Homeowners can also make use of a grey water kit which they can install themselves.
Ben, a representative from Grey Water Kits, says a home grey water kit includes a mini pump, a hair or particle filter, 15cm cable, 4m of clear pipe, a power adapter and an on and off switch.
Ben says anyone can benefit from installing a grey water kit which costs R480. A grey water kit makes life easier because you don’t have to carry heavy buckets of grey water around the house. It also helps with saving water, as you avoid using precious drinking water for flushing your toilet.
5. How long does the grey water system take to install?
Will says it can take anything from one day to six or more days, depending on a myriad of factors.
It takes less than two minutes to install a grey water kit. Ben says to do this no screw drivers, glue or drills are needed. He says quite literally, all you need to do is plug the kit into a power outlet. Once this is done, place the grey water mini pump in the bath, shower or collection bucket. Place the outlet tube into the toilet cistern and then press the on switch to start collecting the grey water.
Mark says grey water systems vary in price depending on the installation process or whether it is a DIY system. Labour is expensive and as such, companies can charge heavily to install systems. He says DIY systems are designed with the homeowner in mind, and installation can be done by a handyman within an hour or two.
6. Does the grey water give off an odour?
According to Will, the more expensive systems don’t have an odour. He says simple diversion systems that can be bought for DIY installation most certainly do have an odour component.
Mike agrees and says if the water is used immediately it is safe, and you can avoid odours by using the water within 24 hours. He says to avoid odours, homeowners should reuse the water before the bacteria can grow. He says it’s key to flush the tank at least once a day.
He says there are more sophisticated systems that can be important that will get rid of odours. They cost around R120 000 to install.
According to Mark, because of the pathogens and bacteria in grey water, the water will begin to give an odour after storage in excess of approximately 48 hours. Grey water should be used the moment it leaves the bathroom or laundry, he says.
Ben says anyone can benefit from installing a grey water kit which costs R480.7. Is grey water safe to use?
Will says this depends largely on the quality of the installation, the care taken with maintenance and the correct use of water.
Mark says grey water is safe to use if used immediately. It must never be consumed or used for cooking, and if it is used to water the lawn, it is a good idea to keep children off the lawn for an hour or two after watering.
8. Can I mix rainwater with grey water?
Will says with sophisticated systems, you can mix rainwater with grey water. However, he says if you have raw, untreated grey water than you can’t.
Mark doesn’t recommend mixing the two because the rainwater may become contaminated with bacteria and pathogens from grey water (far more than rain water picks up from the roof). He says this mixture will begin to smell if collected and stored.
9. How does a grey water system work?
According to Mark, water from the laundry or bathroom flows into the surge tank via the bathroom waster outlet pipes on the outside of the home. This water flows through a filter that is designed to remove hair and lint. It does not remove chemicals like soaps and shampoo though.
“This water activates a pump which will send the grey water to the garden for irrigation. Grey water systems should not be linked to existing fresh water irrigation systems because it tends to block standard irrigation systems very quickly. Use a standard garden hose with a pyramid sprinkler that is moved around the garden.”
10. Can you retrofit a grey water system?
Mark says a grey water can be retrofitted to a home very easily if the waster outlet pipes and gully are visible on the outside wall. If the waste pipes are built into the wall and there is no gulley, this makes a DIY unit impractical as the pipes need to be exposed. A certified plumber will be required for this type of installation, he says.
According to Mike, retrofitting a grey water system involves finding and channelling the plumbing to the system, and providing a power point. He agrees that a plumber should assist with this.
11. Do I need a plumber to install a grey water system?
Mike says it’s best to get a plumber or grey water installer involved.
However, Mark says most homeowners can install a DIY system on a Saturday morning, with a few simple tools.
Households should take care to use soaps low in sulphates and should do research as to what plant types can cope with grey water. Soil quality can deteriorate over time with incorrect use.12. Can grey water be used for drip irrigation?
“In its most basic diversion form, no. When treated properly, yes,” says Mike.
13. Can and should grey water be filtered?
Mark says grey water should be filtered to remove hair and lint - these are two items that are a pipe’s worst enemy.
“Hair gets wrapped around the pump impeller and causes damage to the rubber water tight seals. This results in a pump that does not work at full capacity, and should water enter the pump motor, this will cause the circuit to trip. Electrical shock also becomes a real cause for concern.”
14. How do I protect the environment while using greywater?
Will says this is a highly complex issue. Grey water could be saturated with unhealthy levels of salts derived from soaps used.
Households should take care to use soaps low in sulphates and should do research as to what plant types can cope with grey water. Soil quality can deteriorate over time with incorrect use.
According to Ben, to protect the environment, avoid using bleaches and other chemicals to treat grey water to get rid of odours. Also, all those extra chemicals you add will end up in the oceans. Rather put up with the odour during this time of crisis, he says.
To protect the environment, Mark says do not let the grey water spill into the road or road gutters, and keep it away from ponds and dams.
15. What kind of tank do I need for grey water?
According to Will, basic grey water reuse, where the water is just diverted to the garden, requires no tank as the water can’t be stored and has to be diverted to the garden immediately.
He explains that the higher tech systems all require tanks, which will be above or underground, and vary in size depending on the application.
Mark says grey water systems vary in surge tank capacity. Choose a surge tank under 100 litres that will not store any water. He says large storage tanks are a no-no.
He says as a homeowner, you need to ensure that your tank is UV stabilised if it is above ground and holds less than 100 litres. He says should you wish to sink your tank into the ground, ensure that it is capable of withstanding the pressure from the soil around it. It must be reinforced so that it does not collapse.
Mark says a four person household in Gauteng can generate upwards of 500 litres a day, which can be used for garden irrigation, while a home in Cape Town will only generate in the region of 175 litres per day because of the shower and washing machine restrictions.16. Do I need a pump for the system? What kind?
Mark explains that grey water system pumps vary in size, from the small 400 watt pump up to the standard 900 watt pump. This size pump should be in a position to irrigate your garden approximately 30 metres from the bathroom outlet pipes.
He says your grey water unit should have a pump to remove the water from the surge tank. Gravity fed grey water systems will not deliver water to the far reaches of your garden unless you live on the mountainside or have a steep slope away from the home.
In this case, you don’t require a grey water system. You can attach a 25mm pipe to your waste outlet pipe and let gravity do the work. There are dangers in this, in that there may not be enough slope for gravity to do the work. This will lead to flooded showers or laundries.
17. What are the advantages and disadvantages of getting a grey water system installed on my property?
Will says the most basic diversion systems require hands on owner management and are prone to smell and dysfunction due to ill maintenance and unskilled installation.
“High tech systems enable the user to permanently forgo using drinking water to flush toilets, for instance, which is certainly an insane concept which we as society should have addressed long ago.”
Mark says grey water systems must be seen as a diversion system rather than an irrigation system. In times of drought, he says grey water reuse will assist in keeping your garden alive when you are unable to water with municipal water.
How well it sustains the garden will depend heavily on the amount of grey water the home generates. A single person in a home bathing once a day and doing two or three loads of washing a day will not keep 1 000sqm property alive, but they will keep their prize roses and shrubs going until the rains come. A four person household will have enough water to sustain a small garden throughout the year.
18. What are the long-term effects of using grey water in the garden?
Mark says grey water cannot be used alone without any rain or municipal water.
The soaps in the water need to be washed from the soil every few months as salt can build up from the detergents and soaps we use. This is easily achieved when the rainy season arrives.
19. Potentially how much water can you save by installing a grey water system on your property?
Will says if, for instance, high-tech treatment is employed, a family of five can reuse about 48 000 litres of shower water per annum for toilet flushing alone.
He says the major issue is that the payback period is very long and our water is still too cheap. Most of us tend to make the decision to engage with water conservation systems based only on cost, and not on the more important considerations.
According to Ben, on average, each person in the house may shower once a day. He says if you use a water-saving shower head, this should use about seven litres of water on average.
And if each person flushes the toilet once a day, and there are four people in your house, just by using the grey water kit you can save 28 litres of water every day.
Mike says don’t complicate grey water – the more simple you keep it the more reliable it will be.
Mark says a four person household in Gauteng (with no restrictions on water usage in the home) can generate upwards of 500 litres a day, which can be used for garden irrigation. He says a home in Cape Town will only generate in the region of 175 litres per day because of the shower and washing machine restrictions.
20. Does the system need to be maintained?
According to Ben, grey water by nature is dirty and so you should clean the entire system, as regularly as possible to avoid unpleasant smells building up - at least once a month. - Katlego Sekano
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