Electric hot water heater / Legionella bacteria concerns

[Adelie]

Originally Posted by Rorzech

That bacteria is dead at 130 F. End of story !

At 50 °C (122 °F) – 90% die in 80–124 minutes, depending on strain (D = 80–124 minutes)

At 55 °C (131 °F) – Essentially all Legionella dies within 5 to 6 hours

[Blue Ribbon]

I add 1 tsp bleach for every 5 gal when filling water tanks. Never had an issue with bacteria, hot or cold, in 25 years

[rslifkin]

Originally Posted by Blue Ribbon

I add 1 tsp bleach for every 5 gal when filling water tanks. Never had an issue with bacteria, hot or cold, in 25 years

Unless you have aluminum tanks, in which case this will destroy them in short order.

[Smokeys Kitchen]

Is this only a concern when you allow the water in your hot water tank to stand and not use it for an extended period?

We are on the dock at present - taking showers at the marina. The electric hot water heater is switched off, as we heat water for washing dishes, etc. on the stove. We occasionally turn the electric water heater on to just cycle it, allowing the water to get up to temp, then doing dishes or taking a shower on the boat.

However, even when switched off, we routinely use the hot water tap to fill pots, pans, make coffee, fill sinks, etc. My point is that we do not let the water in the hot water tank stand; similar strategy to using our three separate water tanks.

Don't know if this speaks to your question directly, but in 5 years of living aboard and doing this we have never had any issues with any types of growth in the water system.

[NaClyDog]

Originally Posted by Smokeys Kitchen

Is this only a concern when you allow the water in your hot water tank to stand and not use it for an extended period?

We are on the dock at present - taking showers at the marina. The electric hot water heater is switched off, as we heat water for washing dishes, etc. on the stove. We occasionally turn the electric water heater on to just cycle it, allowing the water to get up to temp, then doing dishes or taking a shower on the boat.

However, even when switched off, we routinely use the hot water tap to fill pots, pans, make coffee, fill sinks, etc. My point is that we do not let the water in the hot water tank stand; similar strategy to using our three separate water tanks.

Don't know if this speaks to your question directly, but in 5 years of living aboard and doing this we have never had any issues with any types of growth in the water system.

Yes, exactly. If water in the hot water tank isn't kept at a high enough temperature, it is possible for the Legionella bacteria to rear it's ugly head. I know that running the engines until the water temp gets high enough (70C or 158F) will kill it immediately.


I wasn't sure that the electric part of the heater would get hot enough for long enough to kill the bacteria before we use it. It would seem that (for the most part) my concerns are unfounded based on everything most folks have stated.

[Sailmonkey]

Originally Posted by NaClyDog

This thread is about hot water heater concerns but, to your point, maybe they have proper filtration in place? I don't know, that is just a guess.

I’m guessing here, influenced heavily by my own feelings on the subject.

Something is going to always be around that can make you ill. Worrying about everything that can make you ill will also make you ill.

Of the hundreds or thousands of boats and rvs with part time in use water heaters if this were actually a problem there would either be dire warnings everywhere, a different method of providing hot water, or even government bans on intermittent water heater use.

Nothing like this exists. So I chose to address this concern as one of millions that are of no concern.

[s/v Jedi]

Originally Posted by Sailmonkey

I’m guessing here, influenced heavily by my own feelings on the subject.

Something is going to always be around that can make you ill. Worrying about everything that can make you ill will also make you ill.

Of the hundreds or thousands of boats and rvs with part time in use water heaters if this were actually a problem there would either be dire warnings everywhere, a different method of providing hot water, or even government bans on intermittent water heater use.

Nothing like this exists. So I chose to address this concern as one of millions that are of no concern.

The reason there are few problems is that people let their water heater heat up to safe temperatures

[NaClyDog]

Originally Posted by Sailmonkey

I’m guessing here, influenced heavily by my own feelings on the subject.

Something is going to always be around that can make you ill. Worrying about everything that can make you ill will also make you ill.

Of the hundreds or thousands of boats and rvs with part time in use water heaters if this were actually a problem there would either be dire warnings everywhere, a different method of providing hot water, or even government bans on intermittent water heater use.

Nothing like this exists. So I chose to address this concern as one of millions that are of no concern.

Don't take this the wrong way but I would much prefer to understand why something is true as opposed to just taking my chances.


Just because there is always risk involved in any chosen activity, doesn't mean I'm going to blindly do things "because everybody else is doing it" when I have a concern.


Cheers.

[Cheechako]

Originally Posted by NaClyDog

How do people deal with Legionella concerns when it comes to mostly electric hot water heater setups?


When we upgrade the electrical systems on our cat, we would like to have less of a reliance on running the engines to get hot water. I understand the engines get the temp in the tank hot enough to kill the Legionella bacteria. But, is this practical / possible with a mostly electric solution (i.e. we only want to heat water when we need it, not all the time and ensure the Legionella bacteria is killed)?


Everyone seems to be telling us to "forget it, just run the engines" but we want to explore other options.
Thanks.

Why would that be different than a house?

[Nick Boxer]

The legionella concern I have is created by my stern shower.
It is situated at a ‘dead end’ of a water route and as our Bavaria is located in Greece with the accompanying warm to hot weather temperatures, the water laying in the dead end pipe, is warmed to a fairly high temperature without the use of a boiler or engine.
This can be ‘stored’ for some time and when the shower is used, that water is vaporised creating creating droplets, the perfect vehicle for the transmission of the legionella bugs.
Does anyone else share my concern?

[Cheechako]

Originally Posted by Nick Boxer

The legionella concern I have is created by my stern shower.
It is situated at a ‘dead end’ of a water route and as our Bavaria is located in Greece with the accompanying warm to hot weather temperatures, the water laying in the dead end pipe, is warmed to a fairly high temperature without the use of a boiler or engine.
This can be ‘stored’ for some time and when the shower is used, that water is vaporised creating creating droplets, the perfect vehicle for the transmission of the legionella bugs.
Does anyone else share my concern?

Add bleach to your water before storage. Run the stern shower a bit.

[NaClyDog]

Originally Posted by Cheechako

Why would that be different than a house?

The water in a house is kept at a constant safe temp 24 / 7 (well, at least in my house). On our boat, we only want to run the heater when we need hot water. That poses a danger. That said, my worries have been addressed.

[Adelie]

Originally Posted by Cheechako

Why would that be different than a house?

Because in houses the water supply has residual chlorine in it from municipal water treatment and because houses have uninterrupted power supply to their water-heaters so the water in the heater is both hot enough to kill all the Legonella and remains so constantly rather than intermittently which may offer the bacteria time to recolonize the tank.

The residual chlorine in tap water is intentional. From the time it leaves the water treatment plant, the water is in pressurized pipes with no exposure to air so the chlorine can't bleed off. The chlorine keeps the whole water system from growing a number of nasties.

A. On board water supplies are not regularly chlorinated, If they are storage tanks are ventilated so the residual chlorine can bleed off and can be recolonized from the environment.
B. Hot water heaters may or may not be set high enough to kill all the bacteria.
C. The intermittent power availability for the heater means that if there is a colony up stream of the heater it may recolonize the heater and possibly down stream from it.

I don't think that Legionella is likely to be a big issue on boats, but I don't think that ignoring the potential problem is a wise more either.

Personally, I would drop bleach in with every new batch of water taken aboard, from rainwater or jugs brought from shore. If all the water came from a water maker I would dose the tank every month or two and trust to luck that it wasn't being recolonized thru the vent from the environment.

[Franziska]

Maybe this is if interest?

https://alb-filter.com/pages/duschfilter?lang=en

Still, I have not heard of cruisers having problems due to legionellas onboard. Not sure why this seems to be the case.

I can follow your concerns. Especially because tankwater is often coming from questionable sources.

Often there are very long water supply lines on the docks, sometimes even with sun exposure on those lines.
So far we let the water run until it's coolish and add silver iodine. Further we have a carbon filter before the taps.

Our shower gets heated only occasionally as we need to run the genset to heat it (no in board engines).

This might be of interest too:
https://sfamjournals.onlinelibrary.w...2.2007.03655.x

[NaClyDog]

Originally Posted by Franziska

Maybe this is if interest?

https://alb-filter.com/pages/duschfilter?lang=en

Still, I have not heard of cruisers having problems due to legionellas onboard. Not sure why this seems to be the case.

I can follow your concerns. Especially because tankwater is often coming from questionable sources.

Often there are very long water supply lines on the docks, sometimes even with sun exposure on those lines.
So far we let the water run until it's coolish and add silver iodine. Further we have a carbon filter before the taps.

Our shower gets heated only occasionally as we need to run the genset to heat it (no in board engines).

This might be of interest too:
https://sfamjournals.onlinelibrary.w...2.2007.03655.x

Thank you for the link. I had no idea such a product existed.


Cheers.