Winterising the water tanks

[Jeva]

I generally leave the water tanks full over the winter period when we are not on board. We use a water maker producing de-salinated water (of course). The question is - Does water that is de-salinated have a greater risk of bacterial growth than water from the tap i.e chlorinated water? I've never noticed a difference over the years, but unless you get sick, how would you know?

 

[RichardS]

If there's any chance of freezing weather it's probably best to leave the water tanks and, more importantly, the pipework empty rather than full.

There must be less chance of chlorinated water developing bugs although the water tanks are vented so eventually the chlorine will presumably come out of solution anyway. Many of us on the forum add a Milton type tablet or some solution to our tanks if we have to leave them with water in.

Richard

 

[Mistroma]

I follow Jeanneau's suggested method of draining the tank, adding some dilute acetic acid solution and pumping it through the pipes. I've refined the process and now open the access hatch and give the empty tank a sponge out before adding acetic acid. I stick a container under the outlet pipe, pour about 5-10% solution into it and pump that into the system. Once that's pumped through I add around 100mls of neat vinegar to the tank. I leave the inspection hatch open, sponge out acid, throw a little water around and sponge that out prior to launch. Tanks are always spotless at start of season, pipes also appear to be clean as first water through seems free of any grot.

 

[Yngmar]

Watermakers generally make very clean water, not because it's desalinated, but because the process of desalination (reverse osmosis) filters out almost all other things as well as the salt. But unless your filters, pipes, pump and tanks are perfectly sterile (they're not), there will be some bacteria in there, and the longer the water sits stagnant, the more time they have to multiply. Then you end up with hordes of legionella bacteria, which can give you legionellosis (very bad) or pontiac fever (mild flu symptoms and thus often misdiagnosed).

I've taken a small sip from my current boats tanks when I viewed her and the water had been sitting in the tank for 2 years. That's how I know about the above ;-)

Therefore I would second the suggestion of emptying and cleaning the tanks, descaling pumps and pipes (white vinegar) and then flushing with fresh water, in addition to disinfecting (bleach = chlorine) when re-filling at the start of the season.

 

[sailaboutvic]

All great suggestions, although I have to say in all the years I have owned a boat in England, all I did was make sure the tank was empty and drained the pipe work the best I could, as to drain them completely would have meant undoing each pipe.
Now on board all the year round we don't have the problem.

 

[BrianH]

If there's any chance of freezing weather it's probably best to leave the water tanks and, more importantly, the pipework empty rather than full.

There must be less chance of chlorinated water developing bugs although the water tanks are vented so eventually the chlorine will presumably come out of solution anyway. Many of us on the forum add a Milton type tablet or some solution to our tanks if we have to leave them with water in.
Richard

I do exactly the same as in the northern Adriatic it is bound to have below zero temperatures sometimes during the winter, once -18°C when someone walked out on the ice in the marina. I read that even Sicily had snow at sea level last winter.

Now I am extra vigilant to get all water out of the system when laying-up as one spring I found a pump split from dregs that had frozen. I periodically clean out the plastic tank but admit do nothing about the tubing - I should really flush them through with bleach [note to self for next month's laying-up].

Every new filling has a proprietary liquid chlorine disinfectant added in just a minimum dose to keep the water pure and without adding any taste. Our NE Italian marina water is good and I try to not run dry when cruising. I once filled the water-tank in Zadar with some disgustingly foul-tasting water that needed a complete tank cleaning when I got back to Italy.

 

[jimbaerselman]

There's an article on my site which gives a fairly comprehensive answer.

See http://www.jimbsail.info/going-foreign/boat-prep/pure-water

JimB

 

[sailaboutvic]

I suprose what you could do is once the tank it drained , remove the pipe from the tank an d blow air through it until water stop dripping out of the tap .

 

[JumbleDuck]

If there's any chance of freezing weather it's probably best to leave the water tanks and, more importantly, the pipework empty rather than full.

I've been leaving water tanks and pipes full over Scottish winters for 25 years now and I have never had a problem. Mind you, I have always had flexible water tanks and plastic hoses, which I presume can take a bit of expansion.

 

[jimbaerselman]

I've been leaving water tanks and pipes full over Scottish winters for 25 years now and I have never had a problem. Mind you, I have always had flexible water tanks and plastic hoses, which I presume can take a bit of expansion.

In water, Scottish west coast, not too much of a problem, thanks to Gulf stream.

Now try out of water, east coast, anywhere from Ipswich northwards to Aberdeen, and hope you don't hit that one year in 5 when things really cool off!

 

[JumbleDuck]

In water, Scottish west coast, not too much of a problem, thanks to Gulf stream.

Out of water.

Now try out of water, east coast, anywhere from Ipswich northwards to Aberdeen, and hope you don't hit that one year in 5 when things really cool off!

The system survived -18^oC a couple of years ago. The West of Scotland is not always the balmy paradise of popular perception.

 

[jimbaerselman]

Out of water.



The system survived -18^oC a couple of years ago. The West of Scotland is not always the balmy paradise of popular perception.

So, presumably, a very well insulated calorifier, no solid cased pumps, enough air pressure in your accumulator and a drained water maker. Or none of the fore mentioned fitted!

 

[vyv_cox]

Disregarding the risk of freezing I think the OP's question is an interesting one. Is there a greater risk of bacterial infection in a full tank of water than in one nominally drained but almost inevitably containing shallow pools of water? My tank has internal ribs that would be impossible to drain without intervention, e.g. baling and sponging. I suspect that a dose of Milton in a full tank may be the safer way.

 

[JumbleDuck]

So, presumably, a very well insulated calorifier, no solid cased pumps, enough air pressure in your accumulator and a drained water maker. Or none of the fore mentioned fitted!

As I said, flexible tanks and plastic hoses only. Any solid bits should, of course, be drained: I make sure the seacocks are all empty too.

 

[Jeva]

Interesting answers and I thank you for your responses. What I didn't mention is that the tanks are steel and not easily opened, so my thinking has always been that full tanks would reduce the possibility of corrosion/ rust . Wrong thinking??
Come the new season the water is always flushed out and replaced. To date we've not had any issues with taste or other nasties (touch wood).

 

[JumbleDuck]

Propylene glycol antifreeze is safe to use in fresh water systems.

 

[TonyMS]

Anyone know where to get Milton in Greece? Or suggest a suitable alternative?

TonyMS

 

[jimbaerselman]

Anyone know where to get Milton in Greece? Or suggest a suitable alternative?

Tony,

Check my link in post #7. Here's a quote from it:

Sodium Hypochlorite is available as ordinary household bleach (not 'thick bleach') in a 3% to 5% solution; check that the bottle says 'suitable for use in water systems' or words to that effect. Brewery cleaning products are the same, but sometimes at higher concentrations. Milton is a <1% solution at many times the price.​

JimB

 

[Mistroma]

Tony,

Check my link in post #7. Here's a quote from it:

Sodium Hypochlorite is available as ordinary household bleach (not 'thick bleach') in a 3% to 5% solution; check that the bottle says 'suitable for use in water systems' or words to that effect. Brewery cleaning products are the same, but sometimes at higher concentrations. Milton is a <1% solution at many times the price.​

JimB

Don't worry about getting rid of the bleach if you add too much. Drain the tank, add a small amount of sodium metabisulphite and re-fill. This will kill the bleach and leave excess sulphite which tastes terrible and the human palate can detect at low concentration (parts per million). Fortunately, it will readily convert to sulphate when you fill with water and you won't taste that at all.

Good tip if you get white wine with terrible sulphite after taste. Pour from one jug into another a couple of times and let it stand for 2-3 minutes. All the nasty taste goes away and wine becomes much more drinkable (been there, done that).

 

[TonyMS]

Many thanks. All I need now is to find a sodium metabisulphite shop!

Tony