48 FEATURE
Successfully harvesting grey- and rainwater
For decades , South Africans have been collecting rainwater for various purposes . The drought in certain areas , however , has now forced all industries to adopt a longer-term view of harvesting water if we are to ensure water supply .
Photos by Burgess and Partners
A backup water supply system in Munich .
By
Cherry Ellis
In the follow-up to a series of articles that kicked off in Plumbing Africa last month , highlighting the standards for plastic and chemical storage tanks , in this edition , we emphasise the procedures to follow for successfully designing and implementing systems to collect rainwater and grey water . ( Ed ’ s note : The article can be read in the May 2018 edition at www . plumbingafrica . co . za .)
Industries , in general , are looking at plumbers to come up with innovative designs that adhere to various regulations and standards set out by the Institute of Plumbing South Africa ( IOPSA ), the South African Bureau of Standards ( SABS ), and the National Building Regulations ( NBR ), which would lead to the successful harvesting of both rainwater and grey water . Before the design or site visit is arranged , clarification is needed to explain to the end user the difference between rainwater and grey water and what it can be used for .
WHAT ’ S THE DIFFERENCE ? Rainwater involves the collection of water from surfaces , especially roofs , on which rain falls and then storing the water for later use . Grey water is classified as water collected from handbasins , sinks , baths , showers , and washing machines . Very important to note is that dishwashers are excluded , due to fat and grease content . Grey water can be re-used for flushing toilets and urinals , as well as irrigation for plants and grass , but experts caution against the use of grey water on vegetables , especially if you are going to eat it raw , as the water might still contain pathogens ( if not treated properly ) and can cause serious health problems .
Once you have decided on implementing a rainwater or grey water system , a site visit is vital before any planning can be done .
Discussing rainwater harvesting , Darryl Brainin , director and head of water and energy sustainability solutions at Burgess and Partners , says that the key factor to keep in mind is what the client ’ s needs are — things like the intended application of the water and the required storage tank space and capacity . Predominantly , rainwater harvesting is used for irrigation and the flushing of toilets . In instances where it is to be used as a
June 2018 Volume 24 I Number 4 www . plumbingafrica . co . za