• March 2020: Elevating the humble loo block

    It is estimated that by 2025 half of the world’s population will be living in water-stressed areas due to growing population. Employing Enviro Loo sanitary technology, construction technology company BOXA and its partners have installed a fixed, off-grid toilet facility at Victoria Yards, a landmark urban regeneration project, near the Johannesburg CBD.

    Read more
  • February 2020: City living demands an innovative hot water solution

    What makes the 158 rental units at the eight-floor 2A Harrison St, Marshalltown overlooking Standard Bank’s head office on Rissik Street, unique is the choice to use a decentralised water heating solution provided by Stiebel Eltron’s instantaneous water heaters.

    Read more
  •  A non-disruptive solution to healthcare plumbing

    By Eamonn Ryan

    Helen Joseph Hospital in Auckland Park, Johannesburg, was built in 1967. Fifty-two years on, following a series of blockages on its old earthenware pipeline, especially beneath the main kitchen, Nu Flow was called in to conduct a CCTV pipeline inspection.

    Read more


What is backflow and why must we guard against it?

Movement of any substance in any direction is called flow. So why the term backflow when water moves from an installation towards the municipal potable supply?

By Patrick Gordon

Patrick GordonFirstly, it is assumed that the water in any installation originates from the municipal supply and so the water that flows back towards there is viewed as flowing back, and thus called ‘backflow’. In most instances this would be the case, so why would we need to guard against it? What has happened to the water that makes it unsafe to return it from where
it comes?

Firstly, we need to take cognisance of the fact that once the water passes the water meter, it now becomes the responsibility of the homeowner and the municipality no longer has control over what happens to it. Once they have lost control over what happens to the water, they do not want to let it back into the municipal system.

We could let the water back into the municipal system if we had it tested and certified as SANS 241 quality compliant, but we know that that is not practical. What could be viewed as potential contaminants?

  • We often have water softeners on the supply to the home and this is done by adding chemicals to the water.
  • The water is often heated in an aged hot water cylinder that will add lime scale to the potable water in a backflow situation.
  • When summer comes and we are filling the pool and fishponds with a hose this could also be a cause of contamination.

So, if we look at it from their view, the probability of getting contaminants from domestic installations is very high, and we have not even ventured into water from alternative sources such as boreholes and rainwater harvesting. Thus, it is no wonder that SANS10252/1 of 2018 says in D.1.1 Design, installation and maintenance: ‘All water supply systems shall be designed, installed, and maintained so as to prevent contaminants from being introduced into the potable water supply system’.

The big question now is not the quality of our water, but how to prevent it from happening. The regulations are very clear on what is expected from us and how to achieve zero backflow from entering the potable system. A follow-up article in the October issue of Plumbing Africa will go into detail on how to achieve this.


PA PlumbdrainLogo100 PlumbingOnline150 TP
External Sales
Internal Sales

Product of

IMD logo White

Interact Media Defined (IMD), is one of South Africa’s leading multi-media magazine publishers READ MORE

Talk to us

JHB T : +27 (0) 11 579 4940
CPT T : 0861 727 663
E : admin@interactmedia.co.za

13A Riley Road, Bedfordview,
South Africa 2007


Cookie policy
Privacy & Cookie policy
Privacy policy

© Interact Media Defined