Legionnaires Disease from RO Water?

[zboss]

All,

We just got a used watermaker and from what I gather, most folks don't treat their water from the watermaker with chlorine or otherwise. Is there a possibility of legionnaires bacteria growing in non-chlorinated tank water?

-z

[Alan Mighty]

Originally Posted by zboss

We just got a used watermaker and from what I gather, most folks don't treat their water from the watermaker with chlorine or otherwise. Is there a possibility of legionnaires bacteria growing in non-chlorinated tank water?

For sure!

But the chances are low, right?

Besides, almost all of the documented cases of Legionnaires disease involve a person inhaling an aerosol of water in which the Legionnaires bacteria is living.

Legionnaires disease is a pneumonia, isn't it? So you need to get the bacteria into your lungs. Do you spritz or mist your tank water into your face and inhale? If you stand under a shower nozzle, your chances of catching something that way go up.

And of course, you need to consider the ecology of the Legionnaires bacteria. It doesn't live by itself in sterile water, right? It usually lives in association with amoeba, perhaps other protozoans, and likely some other bacteria.

So cooling towers of industrial evaporation cooling systems that have been in service for years or decades and have accumulated their own ecosystem of air-borne bacteria and protozoa, are typical places for Legionnaires bacteria. So are natural and artificial lakes and ponds.

Routine cleaning of your tank and water pipes/hoses, to control the growth of biofilm, should reduce any risk massively.

[sailorchic34]

Short answer is yes it can grow in any untreated water tanks. 60-90 degrees F being perfect for growth. It will be killed at temps above 135F ish. It also loves growing in shower heads. So a good idea to once and a while disinfect the shower heads also. That is a common infection point btw.

[Lepke]

No matter how clean the water is you put into you tank, in time it becomes contaminated. Even adding chlorine doesn't last forever in tanks left sitting without use. Chlorine evaporates.
I make all my water, and run it thru a UV sanitizer. But untreated over a few months the tanks will become contaminated. So I add chlorine below the taste threshold. I have a secondary chlorine removing filter providing water to the galley sink and ice cube maker. You can buy a pool test kit for under $10 on ebay and chlorinize to the lowest mark.
About once a year, when the tanks are low, I use a higher chlorine level and make sure it runs thru all my plumbing. Then I drain the tanks and start over.

[jlcnuke]

Just a quick note, if you decide to chlorinate your own water, don't do it upstream of RO membranes.

[deluxe68]

Originally Posted by jlcnuke

Just a quick note, if you decide to chlorinate your own water, don't do it upstream of RO membranes.

Spectra recommends a charcoal filter to remove the chlorine.

[zboss]

Originally Posted by jlcnuke

Just a quick note, if you decide to chlorinate your own water, don't do it upstream of RO membranes.

Check.

We have been using a clean Home Depot 5 Gallon bucket.

[Capt Nemo]

There are RO Membranes available that are made specifically for chlorinated water.

[Pelagic]

Originally Posted by zboss

All,

We just got a used watermaker and from what I gather, most folks don't treat their water from the watermaker with chlorine or otherwise. Is there a possibility of legionnaires bacteria growing in non-chlorinated tank water?

-z

If you consider that many RO systems often sit for long periods without use, when in Marinas or dirty harbours, it will help to put the relatively low risk in perspective.

I would thoroughly clean hoses, filter housings and fittings before assembly.
Include a fresh water flush, before a cautionary pickling of membranes to set your mind at ease.