My diary in November’s issue of Africa Geographic refers to water stress – this includes the increasing demand on the fixed amount of water worldwide, and the deteriorating quality of much of this water.
The question I did not address was what we as individuals can do to alleviate this situation. Firstly, there are the obvious measures like ensuring the plumbing system of your household or business is leak-free. According to South Africa’s Department of Water and Environmental Affairs, a dripping tap can waste as much as 60 litres of water per day and a badly leaking toilet, as much as 100 000 litres a year. We can also use water more diligently by cutting out unnecessary use or by installing more efficient plumbing systems and recycling wherever possible.
But there are other initiatives that would make a significant contribution towards ensuring water sustainability. The most crucial: we all need to become involved in harvesting and storing our own fresh water. How many private homes and businesses today are actively involved in doing this? The bottom line here is that despite the increasing usage value placed on fresh water, it can still be attained for free.
The statistics speak for themselves. According to a variety of sources, an average high income couple with a home in South Africa consumes between 300 and 350 litres of water per day for household purposes, that’s toilet, bath or shower and cleaning and cooking uses, but does not include swimming pools, gardens and the washing of cars for example. This translates into between 9 000 and 10 500 litres per month, or 108 000 and 126 000 litres per year.
And, according to the Green Building Handbook for South Africa by Dr Jeremy Gibberd, ‘the potential rainwater harvesting capacity of a roof can be calculated by multiplying the area of the roof by the annual rainfall’. So if an average roof size is 175 m² and taking Johannesburg’s average annual rainfall of about 725 mm and an evaporation rate of 10% off the roof, homes in this city could be catching approximately 115 000 litres per annum. Imagine what this could do for your annual water bill, not to mention the most important factor here, the annual national demand for water.
Doesn’t this make sense? Why then is it not law that all new homes or developments are required in some way to install water harvesting systems? If we return for a moment to our average home, the most recent values are put at approximately R1.5-million. On average, a 10 000 litre plastic storage tank is going to set you back R7 000, and then another R5 000 for the guttering and piping. This is less than 1% of the overall value, and its money spent on a vital necessity.
Will it take water cut-offs and severe restrictions, much like the electricity outages South Africans have had to deal with over the last few years, before we start behaving more responsibly?