Running a Watermaker Inshore?

[SKMT]

I live on the hook in Miami. Been debating a watermaker. I've read conflicting reports about running a water maker inshore. Some claim you gotta be out in the deep blue. Others say no problem in an anchorage. Here in Biscayne Bay, the water is basically never dirty from run off, but when the wind blows, the water clouds up to a few feet clarity. On the other hand, there are regularly days where the clarity is 6-10ft where i anchor.

I'm assuming the worst that can happen is i clog up pre-filters. I'm just wondering how often they would be clogging, assuming I tried to pick my days and just make water when the clarity is higher?

[Dsanduril]

We average putting water into our tanks from the dock maybe once a year. Usually when we do annual maintenance and cleaning. Otherwise run the watermaker when we need water. Inshore, offshore, wherever. Try not to run in commercial harbors where we suspect chemical contamination. Otherwise, as you suggest, it's really the pre-filters. Depending on where we are these can go a couple of months or a couple of weeks, and yes, you can help by picking your location. In our current locale we avoid running the watermaker in the glacial silt areas, the filters get too dirty too quickly (and some of that stuff is so fine I suspect it can get past the filters), just "green" water and we have no problem running it.

[slug]

Originally Posted by SKMT

I live on the hook in Miami. Been debating a watermaker. I've read conflicting reports about running a water maker inshore. Some claim you gotta be out in the deep blue. Others say no problem in an anchorage. Here in Biscayne Bay, the water is basically never dirty from run off, but when the wind blows, the water clouds up to a few feet clarity. On the other hand, there are regularly days where the clarity is 6-10ft where i anchor.

I'm assuming the worst that can happen is i clog up pre-filters. I'm just wondering how often they would be clogging, assuming I tried to pick my days and just make water when the clarity is higher?

Yah

All the inshore organic material clogs things up

Avoid inshore operation

[a64pilot]

What he said, I have made water in really nasty areas and try to avoid that now as a matter of course. I often pick anchorages based on knowledge of water quality now.
Another thing, if it’s brackish water, be sure you don’t exceed the membranes max production rate, adjust pressure down to ensure you don’t, exceeding the max can damage them. For me that’s 40 GPH and mine is rated as a 30 GPH watermaker so it’s pretty easy to not exceed the max. But some machines push the max and for those you have to be more careful.

Anything that gets past the 5 micron final filter isn’t supposed to hurt the membranes, I believe part of the reason you only make 1/3 of the water that is pumped over a membrane is so that it will flush off the smaller particles, because no filter can keep everything from getting to a membrane, a membrane is of course an extremely fine filter itself.

[SKMT]

In my case I couldn't functionally "avoid" running the watermaker inshore (because I don't take my big boat offshore enough). So basically what I am trying to ascertain is if I would be replacing pre filters so often that the hassle/cost eliminates the advantage of installing a watermaker (for my specific situation).

Be helpful if anybody with local knowledge could chime in.

[a64pilot]

Don’t have any local knowledge, but the vis you report is much better than anywhere I make water excepting the Bahamas, so far as if it’s worth it or not is up to you, as I have an aluminum water tank avoiding chlorine is worth it, were it not for that I’d just get water at the fuel dock and maybe buy 10 gls of fuel or whatever it took to fill up.
Making water on the ICW, I will change filters about every four times I Make water, in the Bahamas I may go for months on a set of filters. I relocated mine so they are easy to access and finally came to the conclusion that cleaning them is a fools game, replace with new.

Watermakers aren’t for everyone, they are in truth a whole other system to maintain and carry spares for and to power and preserve or flush every week etc.
But I don’t think she would come with me without one either, it enables everyday showers that we don’t worry so much about water use, fresh water flush head and a washing machine on board, for us it’s a game changer.
To say nothing about being quarantined in the Bahamas and not allowed on shore, it was awful nice not to have to worry about how and where we were going to get water.

[Dsanduril]

How often are you using the boat and for how long? Unless you are aboard most of the time I'd be more concerned about my pre-filters during the downtime. Doesn't matter how much you flush with product water after production, your filters will grow stuff if they are left sitting. And that will clog them in what seems like relatively few production hours. If you are weeks between excursions then pulling the filters and drying them can be an option, but yet one more task to take care of.

Missed the liveaboard on the hook item. Still, if you have vis of 10' or so I'd expect a couple of weeks to a month on pre-filters. But it's only a guess and depends on how often and how long you run.

[a64pilot]

We are always on the boat, if we weren’t then I’d preserve it with anti freeze. Filters don’t grow stuff on them if fresh water flushed and if you think they will, then throw in a new set, or just leave them out, if all your doing is fresh water flushing, then the water is coming out of your fresh water tank and going through a 5 micron carbon block filter before it’s used to flush, so it’s very clean. Just be sure to install filters before you make water of course.

We have gone months freshwater flushing and then left an put the water maker into production with no issues, but filters should be a 30 sec change thing, if they aren’t then you need to move them so they are.
I learned that the hard way, initially they were in the Lazarette, so to change them meant removing everything from the Lazarette, and that was not good. Now they are in the bilge, easily accessed and if you spill water, who cares? Boost pump is there too, as much as is possible put anything that can leak in a place where a leak won’t hurt.

[a64pilot]

Originally Posted by Dsanduril

How often are you using the boat and for how long? Unless you are aboard most of the time I'd be more concerned about my pre-filters during the downtime. Doesn't matter how much you flush with product water after production, your filters will grow stuff if they are left sitting. And that will clog them in what seems like relatively few production hours. If you are weeks between excursions then pulling the filters and drying them can be an option, but yet one more task to take care of.

Missed the liveaboard on the hook item. Still, if you have vis of 10' or so I'd expect a couple of weeks to a month on pre-filters. But it's only a guess and depends on how often and how long you run.

We make water twice a week, so if I change them every four times, that every two weeks, but I don’t have 10 ft vis, lucky to get 3 ft.
Bahamas as I said I can often go for months on a set of filters.
We use a ridiculous amount of water, it averages out to about 30 gls of water a day, we wouldn’t of course without a high output watermaker.
The people who only use 5 gls a day would of course have filters that last 6 times as long as ours do.

[Dsanduril]

We freshwater flush every time we use the watermaker. And living aboard can sometimes go months without changing the filters. But if we don't run the watermaker for a week or more the filters will start to grow things, regardless of freshwater flushing (and that gets repeated automatically every 4 days). Two weeks without running and it's just easier to put in new filters. Doesn't happen very often as we live aboard and use only water from the watermaker, but there have been a couple of times...

[a64pilot]

Also I had to replace my membranes last year, production rate dropped quite drastically, quality was still excellent just output was way down, and cleaning the membranes did nothing.
It most likely happened by making water in a nasty anchorage and I got some hydrocarbons in or something, so that was an expensive Tank of water. I know where it happened and I shouldn’t have made water there, I knew better.

[Lepke]

I make water year round. In the winter on the Columbia River. I have more filters, but water from fresh water works fine. When cruising I try to stop in rivers to flush the engines and make water. I filter down to 1 micron. If you're in a silty river you need more filters. I use a washable 20 & 5 micron, then a 1 micron before the membranes. I use 4x20 and they last about a year.
In fresh you turn the pressure way down so the output matches the specs of the membrane. If you're in an area with high mineral content, you may need to flush the membrane with a solution for that purpose.
I make water every other day in salt water and about once a week in fresh. Maybe once a year I clean with sodium hydroxide (lye soap). As long as I'm using the watermaker steadily, I don't pickle.
If the production drops and cleaning doesn't help, it's probably mineral deposits.
If you're in fresh water all the time, it's better to use a fresh water membrane. Makes more water.

[raycullum]

Don't do it. I have tried inshore in many many harbors that I thought were very clean and the filters end up completely clogged. Even in Canada with no boats or people around a harbor the biology will get you. I have been told that it might work if you add additional prefiltering capability ahead of the standard filters.

[Dsanduril]

@SKMT, if you want local knowledge, call Tellie at Halden Marine Service up in Ft. Lauderdale. Not only has he forgotten more than most of us will ever know about watermakers, he is also extremely helpful and local to you.

[SV__Grace]

Running a watermaker inshore in fairly clean water is doable, just be prepared to change pre-filters often- pretty much after every use or every other use.

You can use a washable polyester pre-filter such as this and save big bucks. Just wash it carefully and if you find your TDS number going up, change it.

I try to find deep anchorages as a shallow one will have more to gunk up the filter.