Watermaker Usage Question: I have an old Spectra

[Chotu]

Originally Posted by BlueH2Obound

Here is the filter housing:

https://www.wildwestpoolsupplies.com...-sq-ft-172504/

Ours is actually a little older, but this is the new version.

On gauging turbidity, we just look. If it looks slightly cloudy, I'll check the pre-filter after a say 4 hours, which would be about 150 gallons or so. If it looks like chocolate, I'll probably forego making water till conditions improve. While in harbor, we tend to make water on an incoming tide, rather than an outgoing, as the water is clearer. Hope this helps!

This helps tremendously, actually. Thank you.

I think I’m going to give it a go. Back to the original plan of 100 gallons of water tanks and a water maker.

I already have the water maker sitting around. But I was thinking if I can’t run it in a harbor then it’s useless anyway.

If I can run it in a harbor it’s amazing.

[Bill O]

A Secchi Disc is a tool to measure turbidity. Essentially you do "look" at it, but the disc provides a more consistent way to view/measure the suspended material in the water column.

Easy to make one and here is a link showing how to use it. https://www.calvertmarinemuseum.com/...ur-Secchi-Disc

[BlueH2Obound]

We typically make water when we're down about half, since if there is a problem with the water maker, we'd prefer to find out while we still have water in the tanks, rather than when we're out of water! But then we also hold 510 gallons of water . . . I also edited my last post to reflect the exact (and cheaper) housing that we actually have.

https://www.google.com/search?q=dyna...17706999522881

[BlueH2Obound]

Originally Posted by Bill O

A Secchi Disc is a tool to measure turbidity. Essentially you do "look" at it, but the disc provides a more consistent way to view/measure the suspended material in the water column.

Easy to make one and here is a link showing how to use it. https://www.calvertmarinemuseum.com/...ur-Secchi-Disc

I'm familiar with those, similar to what you'd use in a pool when checking water chemistry, but it's not really needed for our watermaker use purposes.

[Chotu]

Originally Posted by Bill O

A Secchi Disc is a tool to measure turbidity. Essentially you do "look" at it, but the disc provides a more consistent way to view/measure the suspended material in the water column.

Easy to make one and here is a link showing how to use it. https://www.calvertmarinemuseum.com/...ur-Secchi-Disc

That’s what I had been thinking of. I remember using them in some oceanography class.

[sailorboy1]

I have thought about one like that. But is the cost of 25 prefilter cartridges

[Tellie]

Originally Posted by BlueH2Obound

We'll have to agree to disagree about watermakers only being useful offshore. With minimal precautions we don't have any hesitance about using them in harbors, unless in heavily polluted areas, or areas of extreme silt.

First, as mentioned up thread, most people's supply of Raw Water comes from a point below water line, in our case, about 38" below water line. The vast majority of petroleum products will float on or near the surface of the water. I am more concerned with turbidity in the water than I am petroleum products.

For that reason, we installed a pre filter in our system when we originally put it in. Our water maker already has 2 each 10" size filters, the first being 20 micron, the second is 5 micron. We installed the following "Spa" filter between the raw water supply pump and the 20 micron filter:

https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

This filter catches most of the large crud in the water, is pleated, has a MUCH LARGER square footage of the 10" filters, and is washable.

On the subject of washability, (yup, that's a word, I just made it up) per the suggestion of our water maker's manufacturer, to "wash" our filters when they get dirty, get say a 50' piece of small line, 1/4" to 3/8" works well, put a small disk with a knot a the end, and thread the line down the center of the filters. cleat them off to the boat while underway, and toss them overboard to trail behind the boat. In no time, they will be flushed from the inside out. Reuse to your hearts content. Filters are relatively inexpensive, but why generate the garbage when you can reuse them and save $$ and waste?

When we are in port with good water for a long time, we often use dock water. We just set the water maker to back flush for 5 minutes or so every three days, changing out the charcoal filter periodically.

Given the cost of our watermaker, and the number of gallons of water produced, we are at about $1.70/gallon right now. By the time we go down to the Sea of Cortez (for the Winter), through the Panama Canal, and over to the Bahama's we expect to be down to about $0.42/gallon or thereabouts. WELL worth the cost of the water maker, besides, for us, it's not about "Return on Investment", or $$ savings, it's about Quality of Life! We just don't have to scrimp on water at all.

On usage, for two people, taking 1 shower each/day, doing laundry, drinking water, washing dishes, fresh water flush in the head, here in the PNW, we use between 20 and 25 gallons a day for the two of us. I expect that to go up somewhat in the tropics, as we will likely be taking a fresh water shower/rinsing off dive gear every time we get out of the water. But our solar is more than up to the task of making water, as well as doing laundry (including drying), and is expected to run one of the air conditioner units as well in the heat of the day (and height of the sun).

As many have postulated here, having a watermaker is probably not a "necessity", but for us, that and having a washing machine on the boat is the difference between "Camping", and "Living"!

Just to jump in here on this part. I would highly recommend that you do NOT use this practice to clean prefilters. You are correct, you are flushing them from the inside out. But you are reversing the filters action. It is now also filtering from the inside out and larger particles are catching on the inside of the filter instead of the outside were its flow is designed for and when you place it back in service you are once again reversing the flow and whatever has been filtered on the inside of the filter is now free to head straight into your system unfiltered. I used to recommend this same practice years ago until I learned a valuable and expensive lesson. The five Micron is the largest sized particulate that can pass through a membrane comfortably. This is why it is industry standard to use a five-micron prefilter in the last line of filtration. If you pull this five Micron behind your boat it will filter plenty of particulates much larger than five-micron on the inside and when you replace it everything larger than five-micron will go straight to your membrane and catch in the input side clogging the membrane. On some systems this can also do damage to sensitive close tolerance parts. A filter pulled behind a boat like this even at slow speeds is going to see a whole lot more flow through it than the watermaker will flow through it. It's almost a jetting effect to the input of the filter where the line is inserted. Just rinse these filters off with a stream of water (Fresh or salt) with about the same pressure as you would see from a shower head and that's it, no scrubbing, no bleaching, etc.. Most of the Smutz will rinse off. If it's any more impacted than that then it is time for a new filter.

[Tellie]

One more thing. People are absolutely correct, you don't "NEED" a watermaker. But then you don't NEED a boat either. There are needs and then there are the pleasures in life.

[Chotu]

Originally Posted by Tellie

Just to jump in here on this part. I would highly recommend that you do NOT use this practice to clean prefilters. You are correct, you are flushing them from the inside out. But you are reversing the filters action. It is now also filtering from the inside out and larger particles are catching on the inside of the filter instead of the outside were its flow is designed for and when you place it back in service you are once again reversing the flow and whatever has been filtered on the inside of the filter is now free to head straight into your system unfiltered. I used to recommend this same practice years ago until I learned a valuable and expensive lesson. The five Micron is the largest sized particulate that can pass through a membrane comfortably. This is why it is industry standard to use a five-micron prefilter in the last line of filtration. If you pull this five Micron behind your boat it will filter plenty of particulates much larger than five-micron on the inside and when you replace it everything larger than five-micron will go straight to your membrane and catch in the input side clogging the membrane. On some systems this can also do damage to sensitive close tolerance parts. A filter pulled behind a boat like this even at slow speeds is going to see a whole lot more flow through it than the watermaker will flow through it. It's almost a jetting effect to the input of the filter where the line is inserted. Just rinse these filters off with a stream of water (Fresh or salt) with about the same pressure as you would see from a shower head and that's it, no scrubbing, no bleaching, etc.. Most of the Smutz will rinse off. If it's any more impacted than that then it is time for a new filter.

Ooh! That’s a good catch! Thank you for this post.

[Celestialsailor]

Originally Posted by Tellie

One more thing. People are absolutely correct, you don't "NEED" a watermaker. But then you don't NEED a boat either. There are needs and then there are the pleasures in life.

I'm going to take those words Tellie and apply them to a few more things in my life...

[Tellie]

Originally Posted by Chotu

Ooh! That’s a good catch! Thank you for this post.

Actually, that's exactly what happened. This customer "caught" a small flying fish inside his filter after I recommended this procedure. It took us three membranes to finally figure out where all the goo came from.

[SailingHarmonie]

Originally Posted by Chotu

And I guess that’s just it. Would you run that water maker that you want to have in the harbor in Long Island? That’s really the crux of my question.

How about in the Hudson river?

I have to wonder if it’s worth it. I have to go through a lot to get it working. I also know I need a membrane. I may actually have to put in a through hull. Which I really really really don’t want to do. I may just put a pickup tube over the edge instead.

But if I go through all of this hassle and expense and can’t use the water maker in Harbors, then what is the point? When I’m on the passage, the water usually lasts. I’m not sitting around showering and having a bunch of guests over doing the same on a passage. I’m not going transatlantic in the near future. It’s more of like a mission up and down the east coast. The time you spend actually sailing between harbors is no more than a few days. It’s definitely not the majority of what the boat is doing. It’s at anchor most of the time. In harbors.

For those reasons I kind of feel like a watermaker is just for dreaming. Like you have it ready to go for that dream trip in some remote islands or something where there is no water available. But in reality, your boat isn’t there. It’s in a harbor.

So I really need to know if I can use this in the harbor or if it’s nearly worthless.

Here is the simple answer (although I admit in practice it is not always helpful): Would you drink the water you are floating in? (assuming it had no salt, of course). In most harbors and heavily populated areas the answer is, No. In a lot of places, HELL NO! You can not rely on a water maker to make it safe.

Desalination membranes are not perfect, they have small flaws. The seals between the high pressure side of the membranes and the product water are also not guaranteed leak free. You have to assume that the product water is cross contaminated--at a low level--with the feed water. Is your Hepatitis A vaccine up to date???

Even aside from contamination with pathogens, coastal waters, and especially bays and estuaries, have water that contains a lot of living, and non-living "stuff" floating in the water. It can clog the prefilters to your membranes very quickly. In some places in a few minutes. It they don't clog, they organic stuff on the prefilters rapidly dies and decomposes. The resulting H2S will go through a membrane and give the product water a 'sulfur' taste. A general rule is if you can't see the bottom, don't make water.

We haven't put dock water into our tanks for years. We have 330 gallons of water storage, and we run the water maker every chance we can to keep it full. But we are actually out sailing a lot, not spending months at a time in a fixed location, and not living on a dock.

For your described usage pattern, in crowded harbors and bays along the east coast of the USA, a watermaker is a dream machine.

[Sawbonz]

Originally Posted by Icarus

Membranes are very expensive

So is lobster. The sun is bright. Water is wet. And?

[CarlF]

Water is a trade off between cost and convenience.

I’m in the Bahamas right now. Prefilters last forever even in harbors. Lots of sun for solar. Water isn’t free at the docks. The cost/convenience trade-off strongly favors the watermaker.

In summers I’m in Maine. I less often make water in harbor - but do if it’s inconvenient to go into a dock or take a sail. Not only do prefilters need to be changed more often but less sun means more genset fuel. Adds about $25/week to cruising costs compared to the Bahamas. But $25/week isn’t a big issue for something as important as water. And groceries are much cheaper in Maine than the Bahamas so it’s a net gain.

I don’t reuse my filters. It’s a smelly job to clean them, they then don’t last nearly as long before clogging again, and they are only about $15. (Usually only the 20 micron needs changing)

I expect that the less clear water will mean a shorter life for the membrane but mine are past 5 years without problem. Membranes aren’t very expensive these days. About $250. If it goes 5 years that’s $50 a year. Less than one night in a slip per year.

I should install an additional high capacity prefilter. This seems likely to save $10/week in Maine.

As for water safety I run the tank dry once a month. After filling I add a 1/2 teaspoon of sodium dichlor hot tub sanitizer powder to the tank and use a pool test strip to get to 1ppm chlorine (a level with no significant smell or taste). I find this once a month treatment keeps the tank spotless. I use a NSF 53 filter on the drinking water tap that I change twice a year ($50/yr)

I would never give up my watermaker as sometimes there is no convenient, or even safe, alternative. Even making water in a very silty harbor can be well worth the extra cost in filters to not have to raise anchor.

https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

[Chotu]

Originally Posted by SailingHarmonie

Here is the simple answer (although I admit in practice it is not always helpful): Would you drink the water you are floating in? (assuming it had no salt, of course). In most harbors and heavily populated areas the answer is, No. In a lot of places, HELL NO! You can not rely on a water maker to make it safe.

Desalination membranes are not perfect, they have small flaws. The seals between the high pressure side of the membranes and the product water are also not guaranteed leak free. You have to assume that the product water is cross contaminated--at a low level--with the feed water. Is your Hepatitis A vaccine up to date???

Even aside from contamination with pathogens, coastal waters, and especially bays and estuaries, have water that contains a lot of living, and non-living "stuff" floating in the water. It can clog the prefilters to your membranes very quickly. In some places in a few minutes. It they don't clog, they organic stuff on the prefilters rapidly dies and decomposes. The resulting H2S will go through a membrane and give the product water a 'sulfur' taste. A general rule is if you can't see the bottom, don't make water.

We haven't put dock water into our tanks for years. We have 330 gallons of water storage, and we run the water maker every chance we can to keep it full. But we are actually out sailing a lot, not spending months at a time in a fixed location, and not living on a dock.

For your described usage pattern, in crowded harbors and bays along the east coast of the USA, a watermaker is a dream machine.

this one is a tough one.

is unknown water ever really safe to drink? I don’t think so. You can’t be sure that the water that you are in is safe.

you could drop anchor in bikini atoll and dig up some stuff you don't want to drink.

people could be dumping barrels of toxic waste off where you are anchored and you don’t know it.

I don’t really know how you can say any water is safe to drink because you actually don’t know. Not without testing.

Then there is the matter of biologically safe. How do you know how many parts per million of different algae that causes red tide poisoning? If you suck that up in and squeeze the toxins out maybe that gets through also right?

what about if you suck up a Portuguese Man-o-war?

How do you know what safe to drink and what’s not?