의심스러운 영예: 낭비되는 물 - 남아프리카공화국의 '가장 물 샐 많은 도시들' 상 수상자 발표

eThekwini (Durban) and Mangaung (Bloemfontein) have the dubious honour of being the two leakiest cities in South Africa, with more than 40% of their purified tap water supplies going to waste.

More than 171 million cubic metres of clean tap water — enough to supply the two biggest cities in the Eastern Cape or the entire Northern Cape — go to waste in eThekwini every year due to municipal pipe bursts, leaking valves or overflowing reservoirs.

This came to light after Daily Maverick requested the eThekwini Municipality to provide a copy of the city’s latest water balance sheet — part of a standardised accounting system to assess water loss and non-revenue water (NRW) in municipalities across the world.

However, eThekwini seemed reluctant to provide the information, which we requested more than a month ago (March 26). Initially, the city’s communications section stalled, saying that it was waiting for the relevant department to collate and provide the information.

Later, following further requests, city spokesperson Gugu Sisilana said city officials had “raised concerns regarding the highly technical nature of the information being requested, noting that it may be subject to misinterpretation by non-technical NRW personnel”.

When we persisted with the request, Sisilana suggested that we try to source the information from the national Department of Water and Sanitation (DWS) instead.

The DWS provided a water loss table for eight of South Africa’s largest metros, clearly demonstrating that eThekwini is losing the largest volume of water nationwide from physical leaks.

The table shows that almost 54% of water supplied to eThekwini by the Umngeni-uThukela Water utility is classified as non-revenue water (NRW). This is water that is either not paid for, not metered, not billed or has leaked from the system.

The biggest component of this NRW is “physical losses” (leaks and overflows), which amounts to 40.4% of the total system input volume (more than 423 million m³ per year).

The volume of lost water is just short of the combined tap water volumes supplied to the cities of Gqeberha and KuGompo (formerly East London) and exceeds the total volume supplied to the Northern Cape.

Though Mangaung’s physical leak rate (41.2%) is almost 1% higher than eThekwini on a percentage basis, the Mangaung losses are dwarfed by the sheer volume of water going to waste in eThekwini.

The metro with the third-worst record is Nelson Mandela Bay, where more than 53% of supplies were classified as NRW (with almost 35% attributed to physical losses).

In Johannesburg, almost half the water supplied is now classified as NRW, with just over a quarter of the losses due to physical leaks.

Among the big cities, Cape Town has the lowest rate of NRW (24%), of which 20.4% is from leaks.

According to a 2015 benchmark study by the Department of Water and Sanitation, the countrywide NRW figure of 37% at that time represented income losses of around R7-billion.

The NRW figure was similar to the world average, but high in comparison to developed countries. For example, NRW figures in Albania and Armenia were as high as 70%, whereas NRW in developed countries such as Australia and New Zealand was below 10%. Germany and the Netherlands have recorded NRW rates of 6%, while the Danish capital, Copenhagen, lost just 4%.

The national water and sanitation department has previously suggested that a realistic NRW target of 25% in South Africa could be achieved within 10 years by investing about R2-billion annually in water conservation and water demand measures.

But last month, Water and Sanitation Minister Pemmy Majodina published a summary of the latest No Drop progress report, suggesting that average NRW on a national basis had reached over 47%, with leaks accounting for 32% of these losses.

In response to queries from Daily Maverick, the department said a more detailed breakdown of water losses and leaks for all municipalities would be published next month (May). DM