OMEGA CONSULTING AFRICA: GOING WITH GREY (WATER) - written by Ina Georgala
The Overberg was blessed with excellent rain this past winter, but now we are heading for our hot, dry summer months again - and towards ever-increasing water bills.
For many ordinary householders, this means water-saving measures like decreasing length of showers, doing less washing and washing up and watering our gardens less often. Harvesting greywater is becoming more popular as a water-saving measure, as we saw during the recent drought. Householders were harvesting water used in showers, hand basins, baths and washing machines for re-use in toilets and gardens.
Did you know that greywater makes up to 75% of the water used in a household but excludes the water from kitchens, dishwashers and toilets that are handled by sewage systems? By re-using this untreated water source, a household can therefore make a considerable saving on its water bill.
All municipalities have their own guidelines for greywater harvesting that need to be taken into account before deciding on a greywater system. New builds have an advantage here, as a greywater system can be incorporated into the house design in line with municipal building regulations and greywater guidelines. Retro-fitting an existing house with a greywater system is a lot more complex and need specialist design advice, such as the advice provided by Omega Consulting Africa (OCA), an engineering consulting firm serving clients in the Overberg.
The main choices you need to make when considering a greywater system is to find a system that makes maximum use of your available greywater but minimises the costs of the purchase, installation and maintenance of the system, says Kent Georgala, MD of OCA. You also need to keep in mind that all greywater systems need a water source and a way to get the water from the source to the point of use and that the cost of the greywater system will be directly linked to the components used to collect, transport and irrigate greywater. “For example, a basic DIY system fitted to your bath's outlet pipe will cost you a few hundred Rand while the installation of a sophisticated system could run into the hundreds of thousands,” Georgala adds. “Each greywater harvesting project is therefore unique and specialist advice helps to ensure the safest and most cost-effective solution for your household or business.”
The most cost-effective greywater system should be simple, Georgala says, which is why a gravity-fed system that cuts out the need for electrified pumps is ideal. Unfortunately, only sites with a substantial fall are suitable for such a gravity-fed system. He also cautions that greywater harvesting systems need to be managed, monitored and maintained on at least a monthly basis - and that homeowners who are not prepared to make this commitment, should reconsider the re-use of greywater.
Before you install a greywater system, here are a few things you should know:
• Greywater should be utilized within 24 hours to avoid bacterial build-up and odour.
• All excess greywater must be collected and returned to the raw water sewerage system or conservancy/septic tank and cannot be stored.
• All greywater should be filtered before use to remove hair and lint, which can clog up pumps and pipes. It is therefore not suitable for micro-nozzle or spray garden irrigation systems.
• Only the most expensive and sophisticated filtration systems can purify greywater of chemicals from the soaps, shampoos and cleaning materials we use.
• All greywater recovery systems should be flushed regularly.
• If you irrigate your plants and lawns with greywater, this should be done on a rotational basis to prevent clogging the soil.
• You need to take care which plants you irrigate with greywater. Because greywater tends to be alkaline, plants such as olive trees, lavender, rosemary and Cape honeysuckle will thrive with a greywater irrigation system, but plants that prefer acidic conditions such as Cape fynbos, will not.
• If you use greywater on your property, it carries an environmental risk and may therefore not leave the property either above or below ground. As such, greywater must be kept away from existing ponds, dams and watercourses.
