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