Does bacteria grow in a hot water heater set on vacation mode?

[decocritter]

Or should it be left on slightly higher than vacation mode?


At what temp does bacteria grow in a water heater that sits?

[Jimmypoo]

bacteria and fish, etc., live in the deep sea next to volcano vents.

Just do what most do. Unless you're gone for more than 2 weeks, just leave it alone.

You won't be depleting it, so you won't have to heat any COLD water coming in.

The flip side is --- I used to turn it off except for 1 hour in the AM and 30 minutes for dishes
at night. Electric heated up lightning fast, and I don't recall ever getting Toxic Shower Syndrome.

I'd still be doing it if the box wasn't in the garage. Were it in the laundry, I'd flip it on/off twice a day.

[decocritter]

Did you save a lot of money?

[davester]

Found this on gardenweb, though I don't know what temperature "vacation mode" is. Typical "low" on a wh is around 120. Most people have them set up around 130 to 140.

* 70 to 80 °C (158 to 176 °F): Disinfection range
* At 66 °C (151 °F): Legionellae die within 2 minutes
* At 60 °C (140 °F): Legionellae die within 32 minutes
* At 55 °C (131 °F): Legionellae die within 5 to 6 hours
* Above 50 °C (122 °F): They can survive but do not multiply
* 35 to 46 °C (95 to 115 °F): Ideal growth range
* 20 to 50 °C (68 to 122 °F): Legionellae growth range
* Below 20 °C (68 °F): Legionellae can survive but are dormant

[guitarist]

Is it a hot water heater?

Or just a water heater

If the water is hot, does it need additional heating?

[OWC Jamie]

Bacteria in a tank is rare.
If you have a sulfer smell it is more likely a anode .

I've had a dead mouse smell to hot water, but that was a growth related to high iron content in a water filter. A new filter and cleaning the filter housing more often keeps it at bay.
If it were to spread or get worse I'd have to bleach the system.


Electric and gas can both be turned off.
Especially if you're also turning the water off, as with a vacation home.
Probably not worth it for a week.

[Jimmypoo]

I don't know how I could NOT have saved money. If the water was still hot enough to heat up in under 10 minutes (reality figure) from being off for 12 hours, the insulation must have been good (it was in the house, not under it, in an attic or a basement) - and if it was the green thing to do, that's really why I did it.

It was a rare event when it wasn't hot enough for a FAST shower even if it was off for 12 hours, but in
the time it took to make coffee it was hot enough.

As for Legionellae - I'm not a member, so I don't worry about that. And if you did - you could always
flush the tank (big deal - 7 or 8 five gallon buckets), and let it refill and turn the heat up higher for that
first tankful following those temp guidelines above from Davester.

Don't forget - that there will be "Fresh chlorinated/chloramine yummy water" coming in to refill it, and that might also help to kill any rascals. But I'd count on the 180 degree temp.

Health Department wants 140-150 for rinse water in a dishwasher that doesn't heat, with a dedicated
water heater linked to NOTHING ELSE (this was 10 years or so ago). I don't imagine that has changed much. And that requirement was stupid for a dishwasher using chlorine based cleaners, when I could
fill a sink and drop in a tab or 2 capfuls of bleach and THAT was also good enough (no temp requirement).

[Bill in NC]

Requirements for any public food service are pretty strict.

IIRC in college, for a private club house offering meals, we had to wash in water hot enough that everybody wanted thicker gloves, and were also required to do a final disinfection (we used some type of chlorine tablet)

For home with a gas water heater I just leave it on 125F all the time.

[JoeH]

jimmypoo wrote:
Health Department wants 140-150 for rinse water in a dishwasher that doesn't heat, with a dedicated
water heater linked to NOTHING ELSE (this was 10 years or so ago). I don't imagine that has changed much. And that requirement was stupid for a dishwasher using chlorine based cleaners, when I could
fill a sink and drop in a tab or 2 capfuls of bleach and THAT was also good enough (no temp requirement).

Not really a bad requirement, because in a dishwasher without its own heat, the rinse cycle water is all tap, and does not benefit from those chlorine based cleaners used during the cleaning cycle. The amount of chlorine or other bacteria control left in the water by the time it hits the pipes feeding your place is only good to control, not eliminate bacteria. It will not necessarily be "freshly chlorinated". Hence they want it to be at least 140, and kill off most bugs by itself.