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Taking control of water provision

Erratic supply is driving change within estates

By Anthony Turton

, |

Taking control of water provision

Erratic supply is driving change within estates

By Anthony Turton

, |

3 min read

The Water Services Act number 108 of 1997 made sweeping changes to the way that water is managed by mandating water service authorities as the only lawful providers of water. But, because of erratic supply and lack of confidence in municipalities, some estates are taking control of water reticulation, which has – mostly – worked fine until now, but it does technically take HOAs, bodies corporate and boards into a murky grey area of the law.

Water services delivery

The idea behind the Water Services Act was that the state would control all aspects of water with distribution to the end user left to municipalities as the third tier of government. Unfortunately, some municipalities are more efficient and effective than others, and about two-thirds of South African municipalities are in distress. So this has not worked well, and service delivery disruptions are common.

Taking control of water services delivery

Service delivery disruptions create a strong incentive for residential communities to manage water services within the footprint of the estate. After all, water is provided by one metered point of supply at the boundary, so it is logical to manage the reticulation system within the estate. Residents and owners already pay levies, so water can simply be added to the existed billing system.

Essential infrastructure for water services delivery

If supply disruptions are common, it is advisable – and may be necessary – to install bulk storage tanks that offer on-site backup storage to supply water to the estate at full demand for two days or more. The estate I live in can survive for a whole week with zero inflow from the municipality, simply because of the buffering capacity that onsite storage enables.

Most estates that do their own reticulation build a tank farm where the municipal water enters the estate. These are kept full by means of a ball valve. This is done by measuring the average daily consumption of water, and then building a tank farm with sufficient volume to hold 48 hours’ supply. The water is stored in the tanks, from the municipal mains, at the point of entry into the estate. All flow into the estate is metered at that single point, so full control is possible. Leaks can be detected by comparing bulk water flow into the estate with the sum of all meters at each home over a defined period of time.

These tanks are kept full by means of a ball valve. Under normal conditions of municipal supply, pressure is provided from the mains into the estate, but with an offtake into the tank farm. That offtake is designed to retain pressure in the mains, even under normal use in the estate. Off-peak water is used to fill the tanks, with very little required to top up. The residents are totally unaware that water is being drawn off as backup, so life continues as normal.

Disruption to supply

While there are other advantages, the system really pays for itself when municipal water supply is disrupted. Typically, this implies a loss of mains pressure, rather than a total shut-off. When this happens a changeover valve is used to redirect the flow of water from the mains into the estate via the tanks, with pressure kept constant by a pump. Residents remain blissfully unaware that municipal mains pressure has been compromised, and life continues as normal because the tanks provide sufficient capacity for full flow at normal pressure. The partially emptied tanks are topped up again at night, or whenever higher-pressure flow returns to the municipal mains.

Water quality and safety

South African municipal water, which is among the safest in the world, is delivered to the end user at a quality that complies with SANS 241 – safe drinking water. But, once it has been stored in tanks for a while, all kinds of nasty things can grow in it. So on-site treatment is a good idea that, with the recent wide availability of backwashable hollow fibre membranes, can be achieved at a very low cost. A typical hollow fibre membrane system is capable of consistently filtering down to 0.1 micron, and in some cases 0.01 micron, at a high level of reliability, thereby filtering out most bacterial pathogens that are likely to occur. This technology has enabled estates to realistically treat their own water at low cost but with absolute reliability.

Augmenting the supply with non-municipal water

Once on-site storage has been developed, you can augment the municipal supply, either from harvested rainwater or a borehole. The latter offers a more reliable supply, but it does involve quite a bit of red tape to get a permit to use groundwater, and there is no guarantee that the permit will be renewed. Borehole water might be reliable, but is not necessarily safe. However, if you have already installed a system like that described above, that will be taken care of. Rainwater harvesting is a great idea anywhere, any time and for any reason, and it can be used to augment existing supplies, but it has the disadvantages of seasonality and unpredictability.

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Recent comments

1 Comment
  • David Furness
    Posted at 15:52h, 05 Jun Reply

    but it does technically take HOAs, bodies corporate and boards into a murky grey area of the law.

    The above is the last part of your introduction to the article but the law is never mentioned in the article but tanks being kept full by means of a ball valve is mentioned twice. The ball valve does not keep the tank full it is the means by which overflow above a certain level is prevented by stopping the water inflow.

    Could have been an interesting topic but an interesting topic wasted, what about estates that produce their own water by means of borehole or extraction from a dam and have their own water treatment plants etc etc.

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