Disinfecting Shower Heads

If you really want to be sure the water is clean then chlorine at swimming pool water strength is going to be more than sterile enough. I personally can't abide the stink of chlorine on my skin and even low swimming pool concentrations I find unpleasant. A carbon filter will make it OK to drink though.

I really think it is overkill to leave the chlorine in the water. A clean tank should not harbour the matter to allow the bugs to multiply fast, so I expect a regular physical clean and bleach shock rinse is the main thing that is needed, even in the tropics. Communal water supplies have just this done coupled with regular testing. The testing isn't too expensive, £20 or £30 we pay I think, so you could do that too if you are worried. Plenty of info on the web. I also fine filter at 5mu the water going in, I leave tanks empty and ensure a regular turn over.

If I had a really rotten mains supply I would use my own RO water.

I have had a number of chest infections on the boat, much more than I would have expected. I blame the shower as since I have taken more care with the water system I have had few problems.
 
sarabande said:
not an expert, I merely wrote the plans to respond to and prevent infection when we had an outbreak in the South West.

It's not just aerosol transmission, physical contact between people (possibly with respiratory transmission also) is a documented here:-

nejm.org/doi/full/10.1056/NEJMc1505356#t=article

where reference is made to "a small area of the nonventilated room" as a possible place of transmission.

I cannot see how a strip wash, using contaminated water, will not give the bacteria a high opportunistic access to where they grow in lungs. Dermal translocation, generation of aerosols by movement of towel, finger/mouth contact, there are numerous ways to get the bug into the body.

There are also non-pneumonic forms of the infection, and it is really hard to see how intimate contact with legionella infected water does not present a very high risk of infection, especially amongst at-risk people.

Would you for instance, go swimming in a pool known to have legionella in it ?


PS. It's not about grovelling, it's about spreading the knowledge - which this thread has done so well - and enabling people to reduce risks by appropriate management and control of the vectors.
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:encouragement:
 
I asked questions and expressed some doubt re. hydrogen peroxide-only early in the thread. I have done some engineering work in the area, but it was never a large part of my job. I like this thread.

a. Silver-stabilized peroxide is very different animal from plain hydrogen peroxide, which is not very effective at practical doses. This is worth repeating.

b. I am in the US. These silver products are just beginning to get approval and are not widely available in the US. Perhaps this will change, which is why I am following this with great interest. There have been only a very few small town tests at this time, that I am aware of.

Different countries, different standards and regulatory approaches. Health stuff is complicated.
 
thinwater said:
I asked questions and expressed some doubt re. hydrogen peroxide-only early in the thread. I have done some engineering work in the area, but it was never a large part of my job. I like this thread.

a. Silver-stabilized peroxide is very different animal from plain hydrogen peroxide, which is not very effective at practical doses. This is worth repeating.

b. I am in the US. These silver products are just beginning to get approval and are not widely available in the US. Perhaps this will change, which is why I am following this with great interest. There have been only a very few small town tests at this time, that I am aware of.

Different countries, different standards and regulatory approaches. Health stuff is complicated.
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Ozone purification is used commercially, I understand, and that is chemically the same as peroxide disinfection, except that the peroxide is generated in-situ by creating O3 and allowing it to react with water (H20 + O3 -> H2O2 +O2) . The O3 is generated electrically, or by the use of ultraviolet. The disinfection effect is a actually caused by the creation of free oxygen radicals, I understand.

All of this is second-hand from my wife who IS a water purification scientist specializing in photocatalytic water purification!
 
One of the mags did such an article some years ago. I cannot remember which one. It may have been a Narrow Boat mag.

Perhaps one of our clever internet sleuths can find it?
 
Antarctic

can you check with your scientific wife if the use of ozone purification relies solely on the H2O2 , please, or whether additional chemicals such as phosphoric acid are used to prevent the H2O2 breaking down too quickly.

I have both the Swiss and Japanese manufacturers of silver-stabilised H2O2 providing me with data on cleaning and sanitising drinking water tanks (especially re biofilm destruction), and also how to provide a biologically inert, potable water supply without the use of bleach. As soon as I get it sorted, I'll share it.
 
sarabande said:
Antarctic

can you check with your scientific wife if the use of ozone purification relies solely on the H2O2 , please, or whether additional chemicals such as phosphoric acid are used to prevent the H2O2 breaking down too quickly.

I have both the Swiss and Japanese manufacturers of silver-stabilised H2O2 providing me with data on cleaning and sanitising drinking water tanks (especially re biofilm destruction), and also how to provide a biologically inert, potable water supply without the use of bleach. As soon as I get it sorted, I'll share it.
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The point is that the H2O2 breaks down to water and O- radicals. It is the O- radicals that actually kill bugs; if the H2O2 doesn't break down, it has no effect! The fact the the H2O2 breaks down isn't important - it is constantly being generated by ozonation, which is where ozone scores over peroxide itself. The big drawback of methods relying on generating oxygen radicals is that there is no long term effect; once the peroxide is gone or the source of ozone removed, there is no further effect because oxygen radicals will rapidly combine with each other to form molecular oxygen, whereas chlorine based systems have a long-acting effect because the chlorine remains present until diluted.
 
dear skippers, please remember you are only disinfecting water to the 'drinking water standard'. You are not supplying an operating theatre, or some factory process. Keep it cheap, keep it simple.

Wilkinson's will supply you with cheap unscented bleach and tablets cheap.

If you have doubts of how to use the product, call the tel no on the packaging and ask for technical assistance. You will be connected to an expert. Explain exactly what you are trying to do. (you must know volume of tank, you must know if you are 'super chlorinating, or just routine dosing) and the technical guy will explain all in plain English.

I have done this numerous times through work and have always had satisfactory advice.
 
I see Chad Valley are running an advertising campaign on YBW featuring a Legionella dispenser for children ...
Screenshot_2016-07-26-09-39-59_zps3f76b4vt.png
 
I think an issue is that much of the biofilm builds up in the pipes not the tanks. In my case I know the water in the tanks remains in pretty good condition with many of these treatments. The "problem" when the boat is left idle for a period of time is that the water sits in the pipes. I find that after the taps have been run for a short period the smell disperses and I suspect the water drawn from the tanks is pretty good. I see that the "problem" with any down stream treatment (like UV) is that if the UV is fitted just after the tanks the water in the pipes may still be contaminated with biofilm. Also I suspect the problem with UV or other means of filtration either before or after the tanks is that the water passing into the pipes may have either no or a reduced level of chlorine.

I think that may be why the peroxide silver combination could work very well. I have just tried it and so far the results have been exceptional - no smell what so ever after two weeks, and no taste either. It will be interesting to see if this lasts for the whole tank. I am guessing that the theory is the water left in the pipes still retains the active ingredients which are only activated as the chemicals react with any biological agents.

Maybe that makes sense and maybe that is why I have found the results so much better - so far so good - and thank you to those who suggested using the silver peroxide solution.
 
thinwater said:
Water works everywhere wish this was true. As a practical mater, depending on temperature, cleanliness, materials, and design, some where from hours to a day or so. Thus, there are stabilizers for chlorine also.
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If the system is closed, like a boat's fresh water system, then the chlorine will persist indefinitely - it is an element and cannot go anywhere. Ozone breaks down to oxygen, and so does not persist. Of course, systems of interest to water suppliers are vented, and do lose Chlorine to the atmosphere.
 
Will it? I understand your point but the reality is, having dosed with chlorine, there is a distinct smell and taste, come back two weeks later and much less smell and taste. The chlorine appears to be going some where.
 
AntarcticPilot said:
If the system is closed, like a boat's fresh water system, then the chlorine will persist indefinitely - it is an element and cannot go anywhere. Ozone breaks down to oxygen, and so does not persist. Of course, systems of interest to water suppliers are vented, and do lose Chlorine to the atmosphere.
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No.

Free chlorine is measured as hypochlorous acid plus hypochlorous ion. The dominant breakdown products is chloride (as in sodium chloride--salt), which is non-reactive and is not a "residual." This is very similar to the breakdown of ozone (O3) into oxygen gas (O2). Oxygen is also an element. Venting is not the difference, since both are very soluble in the range in question (very low ppm).

You can find all of this with Google.
 
thinwater said:
Free chlorine is measured as hypochlorous acid plus hypochlorous ion. The dominant breakdown products is chloride ...
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This is also my understanding, hence the improved performance with stabilised chlorine.

For anyone who is interested, I've sumarised my posts and other info in a post on my Bavaria forum:

Protection from Bacteria in Water Tanks and Shower Heads

This includes further information on the use of NaDCC for water treatment. I have also found a more reliable source of the tablets, as well as some which are 50% higher dose.

Note: linked post has Amazon Associate links.
 
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