[pdqaltair]

This is a little off-topic, since the methods are not directly applicable to sailboats, but some of it is and there is good food for thought throughout.

In a nutshell, though careful selection of water sources, treatment to make the water biologically stable (nothing for bacteria to eat), and world-class maintenance, they do not chlorinate in most areas, most of the time.

http://www.jwrc-net.or.jp/aswin/symposium_archive/images/data/009_inv_es_Gertjan-Medema.pdf

How much of this can be copied by sailors? Where (certainly not world-wide)? Is that enough?

 

[Ikarus]

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)

 

[pdqaltair]

Well said.

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.

Regrowth, for example through the vent, will occur, but the odds of the dust being pathenogenic are remote. Certainly any bacteria can be important for food processing and medical applications, but it won't be fecal contacted. The risk would be the of growth of the few surviving pathenogens, but most evidence suggests that they don't really like to regrow outside of a host. Certain imuno-compromised individuals are at risk, but not most folks.

How much of secondary disinfection (the chlorine you taste) is for control of pathenogen re-growth (little, I suspect) vs. in leakage of sewage (not an issue on boats; the Netherlands focus on good maintaince), bio-corrosion (not an issue on boats; the Netherlands focuses on bio-stable water and flow) and taste/quality issues (any carbon block POU filter would solve that)? Is secondary disinfection really needed on a boat, if the feed water was microbiologically safe (which it should/will be in the US)?

I posted the topic because the Netherlands' practice is an interesting and well-executed counterpoint to common practice.

 

[RichH]

Not only the Netherlands is using such a system as similar systems are appearing all over the EU.
One of the essentials is the total system design wherein all the 'dead-legs' are as short as possible or/and minimized to prevent stagnation and where the total system including houses and other delivery points is constantly active in flow - with a target of of approx 9ft./sec. (2.75 M/sec) within the piping to retard bacterial, etc. growth.
Ozonation is becoming more widely used in the EU but the system has to be constructed of ozone resistant materials - expensive first cost.

 

[tommays]

What passes for clean tap water around here is pretty bad as even the boiler gets up set and requires a water softener and filtration

 

[Ikarus]

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....).

 

[pdqaltair]

What passes for clean tap water around here is pretty bad as even the boiler gets up set and requires a water softener and filtration

No relationship, actually.

Hard water is actually provably good for people, and iron, air, and chloride are no problem.

 

[pdqaltair]

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....).

Comparing water to milk, in this context, is a clear false analogy. Even if no pathogenic bacteria grew in the milk it would be undrinkable due to curdling and lactic acid. An unrelated studied, but the reason food packaging and pharma standards are rightfully VERY different.

Lets start with at a different point with a different comparison; well-water or rain water that has not been exposed to fecal contamination, just environmental bacteria that were not associated with a human host. Though we can nit pick, it is well accepted that uncontaminated well water and rainwater (some interesting Australian studies) are safe without either chlorination or microbial barrier filtration. Surely this water contains some bacteria, but so long as the source water was low in bio-available nutrients and uncontaminated by fecal material (these assumptions are central to this thread), what grows is limited and basically harmless. IF the source water to about has been treated to be free of pathenogens and is ONLY contaminated with dust through the vent and some harmless bacteria in the tank, the water may become distasteful (the degree depending on the cleanliness of the system and the source water) but it won't contain cholera, gardia, or the like.

Not sayin' I would not chlorinate in may cases, but I'm not going to worry over whether my tank maintains a chlorine residual each day.

 

[Delezynski]

Just a note,

We cruised down the west coast of the USA and spent about 5 years in Mexico, then we spent more time in the San Francisco Bay and Delta area, and recently from New Orleans to Pensacola.

We have never had ANY water related problems.

In all that time we used our water maker, or, ALL WATER from a source other than the water maker goes through our UV filter system!

On more than one time that filter system saved us!!! One time in the SF Delta, the filter slowed up and I found the supply (dock water) was like mud! Turns out they had a main break and had not flushed yet.

At our shore side place a year or so ago, they put out a warning that the city water system was contaminated. You could drive and get a small amount of bottled water. We simply hooked up our system and were good to go.

I have seen the same type of filters not long ago for about US $200.00.

A short Youtube I did on the filter;

Greg