I would normally turn a deaf ear to such melodrama, maybe noting that the corporation should not be pronounced Eh-See-See, but Ack. A choking sound would be more on message, eh.
But the near the end of the NatRad story is some safety fairy warning against the dangers of child scalding, saying that tap water should be no hotter than 55 degrees Celsius. They neglect to mention that tap water should also not be cooler than 55 degrees either. This is why:
The optimal temperature for Legionella proliferation in water varies between 32°C and 35°C, but it can easily proliferate at temperatures of up to 45°C. Usually, there is no growth above 55°C, and a temperature of over 60°C has a bactericidal effect.
Ideally, I'd recommend a hot water cylinder thermostat be set at 60 degrees and boil any Legionnaire's Disease out. Knowing NZ's water pipes as I do, that would allow a 5 degree loss of heat on the way to the tap, which is fair go considering this wintry climate at the moment.
There is the worry that people might tune their cylinders too low, causing more hassles than the marginal risk of scalding. A one percent chance of scalding is not equal to a 100 percent chance of poisoning. Sometimes, the cost benefit analysis can get lost in the Safetykrieg.
3 comments:
The dumb thing is that almost no-one gets scalded by tap water except the very young - who would get scalded by tap water at 50 degrees as well. The vast majority get scalded by boiling pots and kettles and hot drinks.
Just another case of safety nazis not bothering to gather some actual facts before pontificating.
Quite right, MacDoctor. I was thinking of including an old primary school friend in the story. He was scalded by a jug of water and had the most extensive skin grafts I have ever seen.
Tap water is usually out of reach, unlike power cords, eh. Thank Dagg for cordless kits.
The NZ building standard specifies a minimum storage temperature of 60°C. It also specifies a maximum temperature at the tap of 55°C (or 45°C for childcare and resthomes).
In the building standards it is clear the only 'safe' way to get tap water at these low temperatures is to get a plumber to install a tempering valve which mixes cold water into the 60°C hot water before it arrives at the tap.
ACC seem unaware of this.
Tempering valves are also useful in solar and wetback systems where the stored hot water temperature can get really high like 100°C - no kidding.
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