SEAN PHILLIPS: Gauteng’s demand-supply relationship for treated water is very tight

Many residents of Gauteng have been experiencing increasingly frequent and lengthy interruptions to their water supply.

Municipalities in Gauteng buy most of their treated water from Rand Water, which abstracts raw water from the Integrated Vaal river System (IVRS) and treats it so that it meets drinking water quality standards. Rand Water stores the treated water in bulk storage reservoirs and pumps it into municipalities’ reservoirs. From there the water is mostly gravity-fed to households. 

To ensure a continuous supply of water to users even in times of drought, the department of water & sanitation sets a limit on the amount of raw water Rand Water can abstract from the IVRS. Dam storage levels can fall rapidly when there is a drought, and it would therefore be irresponsible to raise the abstraction limit when the dams are full. The amount of water in the IVRS therefore puts a limit on the amount of water that can be supplied to residents in Gauteng. 

Demand for water in Gauteng has grown rapidly, largely due to population growth and partly due to increasing leaks in municipal distribution systems. The department's planners anticipated this growth in demand and put in place plans to address it as far back as the 1980s, through the Lesotho Highlands Water Project, which transfers water from Lesotho into the IVRS. The R40bn Phase 2 of the Lesotho Highlands Water Project has been delayed by nine years. It is now under construction but is only due to be completed by 2028.   

Rand Water’s total current supply capacity is 5,200-million litres of treated drinking water per day, and it is already exceeding its abstraction limit from the IVRS. It will only be possible for Rand Water to increase its abstraction of water from the IVRS after the Lesotho Highlands Water Project Phase 2 comes online.

Rand Water has a R35bn capital programme, which is timed to result in substantial additional treatment and storage capacity becoming available when Lesotho Highlands Phase 2 comes online. This includes the recently completed R3.5bn augmentation of the capacity of its Zuikerbosch Water Treatment Plant by 150-million litres per day. This additional capacity is now contributing to reducing the risk of shortages of water for Rand Water’s municipal customers but is also contributing to the over-extraction of water from the IVRS by Rand Water. 

Vulnerable to disruptions

In this context, the demand-supply relationship for treated water in Gauteng is very tight and the system is vulnerable to disruptions caused by heavy load-shedding, electromechanical breakdowns or theft of cables. Usually such breakdowns would not have a noticeable effect on water supply due to the ability to draw on reserve supply capacity, but now there is no reserve supply capacity. Because the water is usually gravity-fed from municipal reservoirs to households, high-lying areas are worst affected by disruptions in supply. 

Rand Water’s infrastructure is well-maintained, and it only loses 3% of its water due to leaks. Gauteng’s municipalities have neglected the maintenance of their water infrastructure for decades, and on average they lose 25% of the water they buy from Rand Water through leaks.

To reduce the risk of water supply disruptions in future the municipalities need to improve their billing and revenue collection and allocate increased funding to maintenance and reducing leaks. There are also investments that they can make in pumps and reservoirs that would improve their ability to withstand the kind of disruptions described above (the City of Joburg is currently implementing several such investments).

Water-scarce country

The water and sanitation minister is co-ordinating regular meetings with Rand Water and the mayors of the Gauteng municipalities. In addition, officials from Rand Water and the Gauteng municipalities are having daily meetings to ensure improved co-ordination of responses to disruptions in supply.

Even after Lesotho Highlands Phase 2 comes on stream, Gauteng’s long-term water consumption will need to be carefully managed because there are limits to which further phases of the project or other water transfer projects can continue to provide additional water to Gauteng at an affordable cost. The reality is that SA is a water-scarce country with limited sustainable water resources, and is among the top 30 driest countries globally. 

The department will be working with Rand Water and the municipalities in Gauteng to implement a more effective communications strategy regarding the need for people to use water more sparingly. Average per capita water consumption in Gauteng is 253l per day, compared to the world average of 173l per capita per day.

If water supply disruptions are to be avoided in Gauteng in future, a culture of careful water use needs to be promoted and awareness raised of the fact that if some people do not use water sparingly, other people will get none.

• Phillips is director-general of the department of water & sanitation.