Play your part in looking after our water resources

Most of us have the luxury of having water on tap in our homes. Most of us also have the luxury of this water being fit for human consumption.

By Patrick Gordon | All images by Patrick Gordon

The water services providers go to great lengths to provide us with water that is termed “Blue Drop” quality. But what do they expect in return for this? We are supposed to make sure that we do not waste this water by letting it just leak out of our plumbing systems.

So our first responsibility is in not wasting it. Many of us are also acting responsibly and we thus do rain water harvesting and we recycle the grey water from our drains. Herein is the problem; we are not allowed to mix our municipal water with these alternative water sources. So how do we keep them separated but also together in our homes?

Non-return valveMake sure that these alternative waters are not used in the same lines as potable waters. We need to make sure that there is backflow prevention on these lines so that none of this water can flow back into the municipal lines. So can we just put a non-return valve in the line and then we are safe? The answer is no.

Pressure Zone Backflow PreventerA non-return valve is only as good as the condition of the seat inside. If any dirt is trapped on the seat, the valve is rendered useless as now the water will be able to leak back. So what to do?

The correct item to fit in the line is a Reduced Pressure Zone Backflow Preventer. This has two non-return valves and a pressure zone that is kept closed as long as there is pressure in the system. As soon as the mains pressure drops away the reduced pressure zone opens up to the atmosphere.

Now if the downstream non-return valve leaks any water that enters this chamber, it will spill out to the atmosphere and will immediately be noticeable and you can take any needed action. In this way there is absolutely no chance of the alternative water entering the municipal supply.

The municipal supply normally is also at a higher pressure than the pressure rating of your domestic plumbing system. This means that we have to make sure that our system is fitted with a suitable pressure reducing valve.

Balanced water pressureThe position of this valve in the system should be such that the whole installation, not just the geyser, is protected by it. This will thus also supply balanced water pressure to all the mixing points in the system.

Once the geyser starts to heat up the water, the pressure in the system will start to increase. This extra pressure cannot push back into the mains supply line as the pressure valve will be in the closed position. To protect the system from the raised pressure an expansion release valve must be fitted.

Some pressure reducing valves are fitted with an extra function and can release the built up pressure. This valve is then normally referred to as a Pressure Control Valve. If the reducing incorporates such an expansion port, no extra expansion valve needs to be fitted. Care needs to be taken however, that no isolating valve is allowed to be fitted between the geyser and the expansion valve.

Vacuum BreakersTwo other valves that need to be fitted are Vacuum Breakers. These valves need to be fitted on an anti-syphon loop so that the system is vented at the highest point in the system. Any water that is higher than the vacuum breakers can, and will be syphoned from the system if the mains pressure drops below system pressure.

CalvacThe hot water system must also be protected from overheating, by a Temperature and Pressure Safety Relief Valve being fitted to the hot water cylinder. This valve will let hot water SANS10252-4out of the hot water cylinder and allow cold water to enter the tank so that the temperature in the tank always remains below boiling point.

Due to very hot water being expelled from the tank we have to make sure that the valve is vented in accordance with SANS10254. The regulation for the installation and use of these valves is covered in SANS10252 part 1. It is of utmost importance that we familiarise ourselves with these regulations.

It has often been said that knowledge is power, but by us using our knowledge correctly and by acting responsibly when we do any installations, we can do our part in the conservation of this valuable resource, our water.

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08 Aug PA 250

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