Watermaker - one that you don't have to run every day?

demonboy

demonboy

Well-Known Member
Joined
11 Oct 2004
Messages
2,237
Location
Indonesia
www.youtube.com
Watermaker - one that you don\'t have to run every day?

Back on the old water maker chestnut. Looking to do extensive cruising into the Indian Ocean and would like to have a reliable (as possible) water maker on board.

Currently thinking of buying a Honda petrol genny to run it, but don't want to do this every day. I was chatting to a liveaboard here and she said they run their water maker once every two weeks because their system takes the last few litres of filtered water to back-wash it.

Can anyone advise me on what makes do this, which ones are recommended, reliable blah blah blah...any comments?
 
Re: Watermaker - one that you don\'t have to run every day?

I am under the impression that it needs to be run at least every three days in order to prevent algae build up.

When will you be in the Indian Ocean, and where? I'm leaving for the Seychelles on Wed next week.
 
Re: Watermaker - one that you don\'t have to run every day?

I never leave ours more than a few days as the filter gets pongy even if I do flush it. I will leave it for ten days after taking the filter out and flushing with fresh. Ideally run it every day then they run nice and sweet all the time. Backflushing still leaves crud on the filter.
 
Re: Watermaker - one that you don\'t have to run every day?

We use a tiny Katadyn 40e - only about 5litres an hour but can just about run it from one of our solar panels (via a battery) We fill a 15l gerry can each day over a few hours and that usually is about enough for us - although we are dirty and smelly cruisers. Don't misunderstand me, we would love a 20 or 50 l/hour monster but we dont usually use that much water daily and dont have the power/space/dosh etc. What it does mean though is it gets a fair bit of excercise. Personally, and I'll temper that with the fact that I'm often wrong, a small one that you can run often is possibly better than a large one run infrequently. Unless anyone fancies giving me a bigger one.....I promise we will wash more.
 
Re: Watermaker - one that you don\'t have to run every day?

I don't know if the Honda can handle it but a 240v watermaker is a good way to go. For a number of reasons, avoid units that need backflushing. Also buy one that can be left for a month without needing to pickle the membrane. HRO is one to look at.
 
Re: Watermaker - one that you don\'t have to run every day?

Hey! Foxy where are you cruising? Just asking so that I can stay to windward of you that's all.
I am an immaculate, shining, highly scrubbed and polished cruiser with errr a black plasic solar bag shower. /forums/images/graemlins/laugh.gif
 
Re: Watermaker - one that you don\'t have to run every day?

Get a 12volt one, run a couple of pints of fresh water through each time you use it, bingo, no worries! Quite a few around.
I have a big mains one, but completely different kind of boat with a genny, in fact two!
 
Re: Watermaker - one that you don\'t have to run every day?

Hey High and Dry! Well Foxy is in the Caribbean but through some quirky twist of fate I am currently sailing the top floor of a semi in west london. Though will be back to the Carib to continue shortly. Probably on the south coast the weekend though so watch out! You will be the one smelling of rubber I take it.....
Actually, on a very slightly more serious note, we plug our solar bags into a diverter valve on our water pump and use that for a hot deck shower as got bit fed up with pulling the stopper out of the bag - not only am I smelly, but clumsy too!
 
Re: Watermaker - one that you don\'t have to run every day?

The main concern with watermakers is making sure that you do not get any algae / bacterial growth on the reverse osmosis membrane that is the "heart" of any watermaker.

Acouple of posters have mentioned "filters" not sure if they mean the RO membrane or the pre filters most units have to filter the incoming seawater.

Although it is also important to prevent growth on the pre filters they are only a couple of quid each if you ruin them, the RO memebrane is nearer a couple of HUNDRED quid so much more vital that you look after it properly.

I also think the "backflush" term used by a couple of posters is a bit mis leading. Some of the more expensive and complicated units may well have a "backflush" function but most only have a freshwater flush option.

Basically you make your fresh water in the normal way and when you have made enough you then divert the last 4 or 5 litres of fresh into a seperate tank / bucket. You then turn a couple of valves and this fresh water is then pumped through the system (the more expensive & complicated units may do this automatically)

The reason for this is to try and leave only pure freshwater in the membrane, pipes and pre filters when you finally turn the unit off. This will minimise the amount of algae / bacteria that is likely to grow in the system compared to leaving it full of seawater. You all know what the heads smells like if it is not used for a few days - the smell comes from the seawater left in the inlet pipes.

If you use the watermaker every day then there is little to be gained by flushing with fresh water because there will be hardly any growth in the seawater in that time. However by flushing with fresh water you can extend the time between operations simply because it takes much longer for the nasties to grow to problem levels in the fresh water - the length of time you can leave it with fresh water depends mainly on the ambient temp.

Now bear in mind that all watermakers use RO membranes made by one of only 2 manufacturers it stands to reason that there is no difference in the length of time you can safely leave the system after fresh water flushing regardless of what make of watermaker you have.

Some makers may "claim" it is safe to leave them longer than some other makers because it is not really an exact science. The thing to remember is that any growth on the membranes will affect performance and is generally cumulative. So if you always leave your units for a week between ops then you will inevitably get some growth on the membranes, and next time you will get a bit more and so on. If you only leave 2-3 days between ops you will probably get minimal growth in fresh water and your membranes will last much longer.

If you have to leave the unit for longer periods of time then you need to pickle it - basically this means filling all the pipes, filters and membranes with a sodium metabisulphite solution (the same stuff that home brewers use for sterilising equipment). This solution effectively kills any bacteria / algae in the fresh water that is used to make the solution, ie you have a sterile solution, consequently you can then leave the watermaker for extended lengths of time without any growth on the membranes.
 
Re: Watermaker - one that you don\'t have to run every day?

With one major exception I agree with every word you said, an excellent post -

Exception, IMPORTANT Spectra watermakers are made of a plastic that is not compatible with metabisulphite which will cause the plastic to crack at high pressures. Only use Spectra pickling solution. We do it once a year so the cost isn't huge anyway.

Other watermakers may also be incompatible with certain chemicals. While manufactures will obviously try to get you to buy their own branded product when a generic will do, sometimes it is essential to use the correct product.
 
Re: Watermaker - one that you don\'t have to run every day?

I have a Power Survivor 80 - haven't used it for ages. Anyone know them and what would be involved in recommissioning it?
 
Re: Watermaker - one that you don\'t have to run every day?

As long as it was pickled just after it was last used, run it for at least 20 minutes before you divert to your tanks and it should be fine. Doing a tongue-tip taste after 20 minutes shouldn't harm you.

Don't run it whilst still in a marina or in silty water ie. run it in an open ocean where the seawater is clear.
 
Re: Watermaker - one that you don\'t have to run every day?

Thank you all for your comments, in particular llamedos (a very useful post). Some food for thought there. One of the interesting comments made was "all watermakers use RO membranes made by one of only 2 manufacturers". This is not the first time I have heard this.

I'm still not sure this helps me make up my mind about 12v vs 220v though. We have 240w solar panels that are, right now in the sun, pulling in 15+amps, so the idea of a 12v system is still attractive. I just don't want to be spending half my day running a water maker, every day, in order to get a few litres in, but I'm even less keen to splash on a petrol genny just to run a water maker.

Any further comments on 12v systems? Like most things I hear they are improving all the time...
 
Re: Watermaker - one that you don\'t have to run every day?

[ QUOTE ]
I'm still not sure this helps me make up my mind about 12v vs 220v though.

[/ QUOTE ]

There is a 3rd option.... power the watermaker pump straight off you main engine. That way you can produce a lot of water very quickly.

I don't have any first hand knowledge of any watermakers as, like you, I'm in the decision making process. Engine driven seemed the best way at first but then I thought... I already have 3 ways of producing 12v electricity (2 engines, one generator) and will shortly have solar and wind generation as well so 12v seems the way to go because of all the redundancy in terms of producing the power.
 
Re: Watermaker - one that you don\'t have to run every day?

As I understand it, running the engine to produce electricity whilst at anchor is not a sensible option. I've been told by a number of mechanics that one should not run the engine in neutral for more than 10 minutes, so to run the engine every day for an hour or more is a complete no-no. Please don't ask me why as I'm no mechanic (!) - perhaps someone could enlighten me.
 
Re: Watermaker - one that you don\'t have to run every day?

The cylinders get glazed and then the pistion rings don't seal properly. But, putting a big watermaker pump on an engine should provide sufficient load to prevent this happening.

btw... Love the website. Just spent 30 mins browsing it.
 
You must log in or register to reply here.

Share this page

Top