34 Design: Dear Mr Plumber
Grey water not a grey area
We are working hard on new projects at the SABS, one project being the development of a standard for the design of water in buildings under the National Building Regulations. It is a longawaited document and will serve as a standard for grey water, among others.
By Vollie Brink( Pr Eng)
Vollie Brink
Vollie Brink is one of the industry’ s longest serving wet service engineers. He continues to serve on SABS committees and has been involved in the Green Building Council Star rating system. Brink continues to consult for various organisations while enjoying a wellearned retirement.
We must look at how to‘ stretch’ our water resources, such as reusing the water.
The reusing of grey water and the harvesting of rainwater have become very high priorities because of the country’ s water situation.
It seems as if the days when we could just assume that when we open a tap we would have clean drinking water— not to mention any water whatsoever— is slowly coming to an end. We must look at how to‘ stretch’ our water resources, such as reusing the water we have and using it wisely.
Something that has always bugged me is the fact that we use pure, clean drinking water to flush our toilets, whereas other people around the corner do not even have drinking water. I also cannot tolerate it when a wealthy person insists on having a shower with multiple shower heads, which use more than 100 litres per minute instead of a comfortable low-flow shower of 10 litres per minute— this is unacceptable.
We are working on a standard to save and conserve water in and around buildings. All of this is hard work and takes time and money. We need people with experience and competence on these working groups, who can contribute their years of experience.
These standards must be appropriate and render cost effective and affordable products.
It must be noted that the reuse of grey water is a serious— no, very serious— matter: it is dangerous and poses a potential health risk. Grey water cannot be reused just as it comes from the fixtures, and to treat it on site in every dwelling is also costly and requires energy. Grey water usually ends up lower than the ground level of a house or a building, where it is collected and then pumped to a higher position, from where it must be appropriately treated and sterilised to be reused for whatever purpose the owner wants to use it.
The Water Research Commission( WRC) has just published a guide for the reuse of grey water.
My view is that grey water should be used for flushing toilets only if it has been treated and sterilised to an acceptable standard. If this becomes compulsory for a level of owner that can afford it, then we will have gone a long way towards not using drinking water for flushing toilets.
We should start with all new buildings, specifically communal buildings such as townhouses and apartment buildings, and collect the grey water and reuse it for flushing toilets. This will have a significant effect on the water consumption in our cities and elsewhere.
The dti, with stakeholders’ input, is in the process of revising the National Building Regulations Act. In my view, it is in good hands. I hope it will address several problems and issues and that it will be better than the existing Act.
In addition, we are working on a standard for grey water that will still take some time to complete, but the guide produced by the WRC is available and could be used.
Many‘ systems’ are available on the market for the reuse of grey water, but I would really caution you to make sure that you only install systems that will comply with the proposed new standard and that you consult the WRC’ s guide.
Water is life and we must use water sparingly. Do not wash your car with a hosepipe; change your WC cistern to use a three- and a six-litre flush, depending on the nature of the flush; use a broom to clean your pavement; instead of having a bath, rather shower under a low-flow shower of only 10 litres per minute; insulate your hot water pipes; and change your hot water piping so that you do not have long‘ dead legs’.
Please do not forget to install air release valves at high points, this is important.
Until next time. PA
April 2017 Volume 23 I Number 2 www. plumbingafrica. co. za