Unreliable Water Supply

The supply of basic amenities is getting more and more unreliable, thanks to our authorities placing very little value on competence, or established institutional learning, when retaining, or appointing staff, for the various government departments and other relevant service delivery organisations. So now in South Africa, we have a proliferation of extremely expensive organisations and departments, that simply cannot perform the function they were supposed to, with any level of reliability.

The result is a rapid decline in the quality and reliability in all our basic services.

Water is no exception.

However, as we all discover from time to time, unfortunately, is that when the water supply is cut off, life becomes difficult quite quickly. Simple things one takes for granted, like being able to wash your hands, or flush the toilet become a problem. Never mind cooking or making coffee and tea.

Why A Buffer Tank?

If one installed a buffer tank that was kept full by your normal council supply, then in the event of a water outage, you could use the contents of the tank for basic needs, until the supply was restored.

Think of the buffer tank as the equivalent of an electrical battery that you kept plugged into a battery charger, and then when the power failed, you could use the battery, until the power was restored.

How Would it Work?

If one used a conventional drinking water storage tank, commonly available from various suppliers, and installed a float valve (similar to what you would find in your toilet cistern), such that the float valve would cut off flow from the council water supply into the tank when the float detected that the tank was full, then that arrangement would keep the tank topped up using council water, as you used the water from the tank.

In the event that the council water was cut off, you would have a full tank of water to use as a buffer, until the council water flow was restored. Once council water flow was restored, the tank would automatically fill up again.

Limitations and Problems that Need to be Solved

There are a number of issues that need to be recognised, that will affect the practicality of this idea, in each specific case:

  • Water flows downhill, so the buffer tank would need to be installed at an elevated height in such a way that the water flow would be useful to you. This could be as simple as sticking the tank on a small stand with a tap at the bottom of the tank, so that you could open the tap and then fill a bucket or other container, as necessary. A more sophisticated set-up could be installing a tank in your roof (or outside on a raised platform), and then perhaps supplying that water to the toilets and maybe a few dedicated cold water taps, such as in the kitchen and bathroom. The idea is that the buffer tank should supply a few taps that you use everyday. But in the event that the council supply was cut off, those taps would still continue to supply water for some time, until the buffer tank ran dry.
  • Council water is pressurised to about 3-4 bar, but once water flows from the council supply into the open tank, the water pressure drops to ambient pressure. You cannot connect pipes containing low pressure water, to pipes containing high pressure water, because you would experience weird problems, as the high pressure water pushed “backwards” into the low pressure pipe system. These problems may include burst pipes and fittings, or the buffer tanks starts overflowing continuously from the high pressure water flowing into that tank through the pipe which it was supposed to flow out. The simplest most practical use of the tank water, which avoids these sort of issues, would be simply to supply a few dedicated taps and perhaps the toilets with buffer tank water exclusively. But you cannot connect water from the buffer tank to any mixer tap which is also connected to the high pressure council supply. This means that you cannot use water from the buffer tank for showers (unless you get a lot more creative with your plumbing). There are ways to re-pressurise the water from the buffer tank, such as either raise the tank about 30-40 meters above ground level, or install a pressure pump on the outlet of the tank.
  • Water is quite a heavy substance. One litre of water weighs about one kilogram. So depending on the size of your tank, the support for that may need to be quite substantial. If you wish to place the tank in your roof, you may need to substantially reinforce the roofing structure to be able to safely hold the tank. If you have a very large tank in mind, you may need to consult a professional engineer to sign-off on your support structure design. For this reason, it may be better to place a large tank on a suitable commercially available stand outside.

What Size Tank?

The way to estimate this would be to:

  • First decide what water uses you want to continue during a water outage. For example, taps in the kitchen and bathroom, as well as flushing the toilets.
  • Estimate your daily consumption from those water uses. For example, how many times is the toilet flushed each day, on average, how much water do use from each relevant tap each day?
  • Decide how many days you want your buffer tank to last.
  • Multiple your daily use, by the number of days, to get an estimate of the tank you would want.

Obviously this requirement may clash with your budget, as well as with practical limitations, such as available space, building structure strength limitations, building restrictions, bylaws etc, so you may have to iterate this thought process a few times, until a suitable compromise is reached between the opposing requirements.

What Parts Would you Need?

The exact components necessary would obviously depend on the specifics of each installation and the overall system design. But the components needed would fall into the following categories:

  • The tank itself, together with the proprietary plumbing fittings connecting to the tank. There are many commercially available tanks in a wide range of sizes, specifically designed to store drinking water. The most common types are roto-formed plastic tanks that have light-proof linings (to prevent algae growth). The companies that supply those tanks could probably offer plenty of advice on the most appropriate tanks to meet your requirements, as well as the fittings necessary, to allow you to connect the tank to your plumbing system.
  • Some form of float valve which will fit inside the tank, as well as be compatible with the tank fittings. The company supplying the tank, could probably either supply that valve, or be able to advise which valves are normally used with their tank.
  • Some sort of support structure for the tank. Again the company supplying the tank will probably be able to provide support specifications for each of their tanks, because elevating these tanks is a common requirement by users. Make sure you use a support structure that completely meets those specifications.
  • If the tank is to be placed in your roof, you may want to consider an overflow/spill tray that will be placed under the tank and which will catch leakage, overflowing or spilled water from the tank and allow that to run away down a spill pipe (similar to the tray placed under most geysers).
  • Various piping and plumbing fittings necessary to connect the tank to your taps and toilets etc.

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