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Well, being in The Netherlands and actually having noticed the transition from chlorinated to unchlorinated water here (which means tap water is now actually nicely drinkable, before it was noticably chlorinated around here, but not even remotely as much as is usually done in the USA), let me put in my EUR 0.05.

Several of things are of note to the system that is used that I noticed while checking up on the details.

  • The source of the water is either clean or cleaned water (slow sandbed filters and the like). So if you want to do this, you need to add filters to the water being input into the system if the water doesn't meet the standard.
  • Hydraulic integrity, so no damage to the pipes. This should be doable on boats, but you do need to keep track of any damage and leaking. However, there is a glaringly obvious weakness there, the vent line. You will want to install a high quality air filter (hydrophobic teflon type probably) on that line.
  • High flow on the main pipes. Essentially you can't do this, however, the reason for this is to make it impossible for any growth to happen in nooks and such in the pipelines. So having smooth pipe setups with very little in terms of junctions might help.
  • Dispense time disinfection, the water resevoirs use UV or ozon disinfection before it flows into the pipes. Doing this on a boat is actually an option, IF your power would be sufficient, but that is a big if. Another option is to do this disinfection when you fill your tanks with water, but that runs into the issue that no such form of disinfection is 100%, it just reduces the infectant load to be safe, for immediate use, so any long term storage can still lead to regrowth.
  • Backflow prevention. I think you can do without this if the only outlet is taps, but if you have a shower or the like you might need to be careful about it.

So the problem is that the water in the tank still has some bacterial load even if it's nominally disinfected when you fill it. The Dutch system solves this by having high flow (so it can't regrow). You can then chose to filter and sterlize at dispense time, but unlike chlorine, generating ozone or UV takes power, which might be in short supply, it also might leave enough toxins in the water to be dangerous.

Note that most sailboats in The Netherlands don't use chlorination and as the water from the tap isn't chlorinated either, they don't have any protection against growth. But on the waters here you don't really need a big tank, so you have the water for perhaps 3-4 days, which is perfectly fine flow levels. Boats do shock chlorinate their water systems at the end of the season, but then fully flush their tanks.

(wow, a bit long and I still haven't said hi on the forum, oh well)
 

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The vent issue is well taken; strange that though the US plumbing code requires at least a bug screen (16 mesh), few boats even have this. Easy fix, as discussed on this forum.
I'd go beyond that, but yes, anything is better then nothing. (It's not in code here actually, but it is a general guideline).

Is secondary disinfection really needed on a boat, if the feed water was microbiologically safe (which it should/will be in the US)?
It is note, microbiologically safe, which is the same idea as pasteurized milk, aslong as it's consumed in a reasonable time, there won't be any bacterial growth beyond what your immune system can handle. That is to say, if the water is allowed to stand still for a significant period of time and at moderately high temperatures (as encountered on a boat sailing in summer), it can regrow it's bacterial load from the remaining bacteria.

Mitigating that would need either upping the standard for the fill water and insuring the system is clean, reducing the amount of time between fills or possibly ciculating the water through filters (but those themselves form a breeding ground). If you can't do any of that, secondary disinfection will still be necessary, either by raised chlorine values (which can then be carbon filtered out at dispense time) or UV systems (ozone is not realistic in a small scale setting, small scale ozon producing systems use UV for that....).
 
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