Greywater Harvesting
WHAT IS GREY WATER?
Grey water is defined as water from baths, showers, hand basins and clothes washing machines or the laundry. Any water from any other source ( toilet water, and from kitchen and bidet’s) is considered ‘black water’, and must be allowed to proceed to the sewer, and be treated by some sort of sewerage treatment works.
A bath uses 120 litres and a shower 80 litres of water. When used, that water is called grey water. You pay for it, and then it all goes down the drain. ‘Water Rhapsody Grey Water System’ uses this grey water to immediately irrigate your garden, saving you a substantial portion of your water bill.
Grey water is the solution to the problems relating to demand and supply management of water not only in South Africa, but worldwide.
* Supply management of water is water supplied by the municipality to your doorstep. The supply of water is severely stressed in South Africa. In simple terms, we do not have any more places to put any more dams, in any more rivers.
* Demand management is how you or the municipality manages the use of this precious resource.
Grey water is the biggest contributor to wastage of water and though knowledge of this very useful source is growing generally, this knowledge is still woeful. At best, 33% of water consumed in the home is thrown away, and at worst perhaps 50%. It is preposterous that any municipality allows this precious source of good water to be thrown away. Grey water is very useful for two purposes, re-used for toilet flushing or for irrigation purposes.
Rules of Grey Water
There are several rules for the re-use of grey water and these are:
1. Thou shalt not store grey water: This is the first law and may not be changed: the problem is that grey water has temperature and food value for anaerobic bacteria to breed and produce methane and hydrogen sulphide, the stuff that smells so badly.
Any talk of a “tank” into which grey water is fed and used for any purpose whatsoever is simply not possible. Any “tank” will build up sludge, and this is quite unacceptable.
2. Do not let grey water pool: Sending water to flood irrigate gardens on a regular basis means that a bacteria will clog the soil, preventing penetration of water into the soil, that needs to be overcome by some sort of cultivation.
3. Grey water must be sprayed under very low pressure that does not exceed 6 meters from the head of the sprinkler.
This will prevent any atomizing of the sprayed water particles. Grey water contains bacteria of many types, and the particles of water must land on the soil, and not become airborne to be breathed in downwind. Spraying means that the likelihood of polluting groundwater is eliminated. Grey water is dirty water and may not be fed into any irrigation system; this includes drip irrigation, because all irrigation systems require clean water and high pressure.
4. Perhaps the most important aspect to the re-use of grey water for irrigation purposes is what to use for washing powders. The use of any phosphate-rich washing powder will poison your soil over the long term. There are phosphate-free washing powders on the market, and these must be used.
Rainwater Harvesting FAQ
Why do you recommend collecting rainwater?
There are as many environmental reasons associated with rainwater harvesting as would befit a super PhD thesis. However one very important reason is to reduce stress on our estuaries via less extraction from rivers during the rainy season. If possible, everyone should harvest rainwater from their roofs rather than using municipal water. It is also very important to provide the means to become as independent as possible from the municipalities’ supply, while at the same time guaranteeing supply in spite of possible – and likely – water outages in the near future.
What sort of roof should I use to maximise my rainwater harvesting?
The most efficient roof surface is a metal roof. This means a corrugated iron, flat iron sheet, or IBR profile. You cannot harvest rainwater with a thatched roof. Tiled roofs are not as efficient as metal for collecting rainwater. Here are the average calculations:
11 mm of rainfall for metal roofs produce 1000 litres of harvested rainwater for every 100 sq. metres of roof area and 16 mm of rainfall for tiled roofs produce 1000 litres of harvested rainwater for every 100 sq. metres of roof area.
Whatever your roof, we are able to determine precisely how much storage of rainwater you should need.
Water tanks are ugly! How can I conceal a tank away from my house, but still use harvested rainwater?
Water tanks no longer need to stand at a wall of your house under the roof-eaves. Our system to harvest rainwater is unique. The unique item is the ‘Water Rhapsody Rain Runner’. This device is central to being able to harvest rainwater in a sustainable way. You are able to fill a rainwater tank or multiple rainwater tanks without the need for any pumping at all.
You simply make use of gravity to make your rainwater harvesting sustainable. The ‘Water Rhapsody Rain Runner’ is crucial to this end, and will deliver water to any place around you house or garden as long as the head of the ‘Water Rhapsody Rain Runner’ is higher than the head of the tank, then harvested rainwater will be delivered in an underground pipe from the house to your tank in a ring-main. All pipes from the ‘Water Rhapsody Rain Runner’ around your house or commercial buildings are teed into the ring main.
The ‘Water Rhapsody Rain Runner’ therefore makes the complete system of harvesting rainwater simple, sustainable and safe.
Definition of the ‘Water Rhapsody Rain Runner’: The ‘Water Rhapsody Rain Runner’ is a self cleaning device placed in your downpipe to send harvested rainwater by means of an underground pipe to water tanks without any chance of the delivery pipe blocking or clogging in any way. The ‘Rain Runner’ receives the water, sieves out any debris and delivers this water via an underground pipe to your remote water tank.
How do I pressurise the rainwater for household use?
We provide all systems to harvest the rainwater (Water Rhapsody Rain Runners), the underground piping from the gutters to the tanks, the rainwater storage tanks, and a pump to pressurise the water for the supply to the building (Grand Opus pump). The pump starts soon after you turn on a tap, and switches off after all taps are closed. This is all automatic.
What is involved in the installation?
1. Installing our system to harvest rainwater (‘Water Rhapsody Rain Runner’) into each downpipe.
2. Supply and installation of suitable size and number of rainwater tanks.
3. Pump to deliver the water to the house. If you have need for high peak times of water usage we can install more pumps in parallel to increase the higher volumes required.
4. Electrical supply point.
5. A ball valve to augment supply in the water tanks from municipal mains. This gives you an emergency supply at all times.
6. An override to revert to municipal mains should your rainwater be exhausted.
Contact jeremy@water-rhapsody.co.za to get your house water wise!
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