Inside Johannesburg Water’s Commando System

Ageing infrastructure, prolonged load-shedding, vandalism and a growing population have put Johannesburg Water’s Commando System under serious pressure. It is prone to water shortages, along with low water pressure, especially in highlying areas of the supply zone.

Named from where the Rand Water supply meter is located (Commando Road, Industria), the Commando System receives water from the Rand Water Eikenhof Pump Station and supplies water to:

• three hospitals (Rahima Moosa Mother and Child Hospital,

Helen Joseph Hospital and Garden City Hospital)

• two universities (University of Johannesburg and University of Witwatersrand)

• parts of Region B (Northcliff, Melville, Auckland Park, Bordeux and Bryanston extensions)

• Region F (Johannesburg CBD, City Deep, Robertsham, Linmeyer, Fordsburg, Kibler Park and Mulbarton).

The reservoirs are interdependent, meaning they rely on each other for water. Therefore, an issue of supply to one will have a ripple effect, causing the others to also lose supply. The Crosby Reservoir feeds the gravity zone (the area that is on the outlet of the reservoir such as Langlaagte and Industria) and pumps into the Brixton Reservoir. The Brixton Reservoir has its own pump station and feeds the gravity zone (Brixton, Mayfair, Hursthill, Jan Hofmeyer) and highlying areas (Melville, Auckland Park) through the tower.

Brixton’s pump station pumps water from the Brixton Reservoir to the tower. Once water reaches a particular level in the tower, the pump will stop. The entire Commando System requires a minimum water flow rate of 2 500 litres per second from bulk supplier Rand Water to supply all four reservoirs and sustain the network. However, the water flow will need to increase to ensure that water supply is greater than water demand.

“If reservoirs are at 80% capacity, Johannesburg Water is confident that it can continue to supply water to residents, even if a challenge arises. But due to various issues, it is a luxury to have full reservoirs. When reservoirs are 20% and below, the system will experience low water pressure and the high-lying areas may not receive any water,” says Gugulethu Quma, electromechanical engineer: Operational Networks, Johannesburg Water.

He adds that while parts of the Commando System can lose capacity in a matter of hours, it can sometimes take days or even weeks to replenish them. This is because Johannesburg Water must continuously supply water while trying to build reserves at the same time. “There is also the additional complexity of removing air from the pipelines and dealing with burst pipes due to pressure changes in the system.”

Challenges

“Most of this infrastructure is ageing and was built in the 1940s. Furthermore, theft and vandalism at all three of the complexes are a major issue. While we have security on the sites and armed patrols at night, vandalism and theft still regularly occur. This affects water supply and can be time-consuming to rectify. When thieves steal infrastructure such as valves and cables, it takes time to procure replacements while residents are left without water. Importantly, budget for infrastructure maintenance and upgrades has to be redirected to security measures,” says Quma. Power outages are another major challenge that impacts water supply. This entails, first, load-shedding. While the Commando System is exempt from the lower levels, owing to the critical nature of the system, it is subject to higher stages of load-shedding because of the strain on the grid. The same applies to Rand Water, and the water board can sometimes only supply a portion of the agreed-upon water to Johannesburg Water. This places pressure on the system.

Furthermore, there have also been long periods of power outages at the Commando System due to incidents of cable theft and vandalism to City Power’s infrastructure.

Unfortunately, a backup generator cannot be placed at pump stations because of security issues. “These have become high targets for crime syndicates. It is a safer option to remove the generators to protect the lives of those that are protecting our infrastructure. Putting in a generator is a security risk on its own,” adds Quma.

Renewable energy can only be used to power auxiliary and security systems, as pumps are too energy-intensive. A stable, consistent supply of power is needed to run the pumps.

Fixing the struggling Commando System

According to Quma, the Commando System needs additional storage capacity. “However, it is important to maximise the utilisation of all the reservoirs, particularly the Crosby Reservoir that has a 46 Mℓ capacity.” A project is underway to add storage capacity to the Brixton complex. This is because the Brixton system is overworked and demand is often greater than supply. A second reservoir and water tower that is slightly bigger than the Brixton Reservoir will be built and located fairly close to the complex. It will be housed at a primary school, and will serve as a multipurpose facility. The reservoir will be built underground, and the top will be covered and repurposed as a playing area for the children. “This will supplement the supply from the Brixton complex,” explains Quma.

A reconfiguration will be done to allow the Hursthill reservoirs to supply the Brixton Reservoir should the Crosby Reservoir have trouble.

The Crosby Pump Station will be upgraded in the next two years, while there are also current plans to further secure the Brixton, Hursthill and Crosby complexes.

Johannesburg Water recently completed linking Hursthill Reservoir 1 to the Northcliff Reservoir. This was done so that so that the Northcliff Reservoir – which is stable and has enough bulk supply – can boost this struggling Hursthill reservoir.