# Watermaker Plans



## Martinini (Jun 18, 2008)

After much searching I found this http://www.westward-ii.com/PDF's/How%20to%20build%20your%20own%20watermaker.pdf


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## dieselboy (Aug 29, 2009)

Very interesting...


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## RichH (Jul 10, 2000)

Litchfield's methodolgy and explanations are spot on. If you follow his directions, etc. you can build yourself an engine driven watermaker for ~$1000.00 for a system that will last for several years, double that for a system made of bronze/stainless. Costs will vary based on how well you can 'shop' for the parts. 

Making your own watermaker is quite easy and a DIY watermaker can have most the components 'spread-out' all over the boat if you have storage volume issues. 

I was involved in the engineering of sophisticated RO, etc. equipment for many many years and will say that what Litchfield presents is 'spot on'. For simplicity and cost savings, his 'manual control method' is also 'spot on' as there is nothing better than a 'cognizant human brain' when it comes to 'control systems'.


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## night0wl (Mar 20, 2006)

Looks like a lot of the equipment here would be used for my A/C (intake thru-hulls, strainer, impeller based feed water pump, output thru-hull above the waterline, etc). What are opinions around t-ing into that existing equipment for this watermaker?

Another benefit for me is that my water tanks are already on the port side, right by where the A/C intake already is, so piping runs will be smaller to boot.

Although there would be a looong way to pipe for an engine mounted pump. May have to go 120V pump for the high pressure side of things.


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## RichH (Jul 10, 2000)

Sure you can tee in a lot of line to other equipment. Only you have to be sure that the 'draw pressure' of the booster pump doesnt suck air back through the 'other' devices and cause a slug of air to hit the high pressure pump ... or worse the RO membrane. Such will work if you have valves on the discharge of the 'other' equipment that is 'tee'd into' the RO unit. 

Using a 120v pump has definite downsides, as when you have 120v available you usually dont have 'decent' and low particle water to draw from (harbor marina, etc. etc.). Best is 12vdc or engine driven so that you can reliably take on water that has some degree of low particle burden - out in the open ocean or in some remote & not-close-to-*pooping-in-the-water-people*, location . ;-(

A high pressure deck wash pump is ideal to feed the lowside of a high pressure RO pump; and, you have the availability of the deck wash when the watermaker is not on.


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## night0wl (Mar 20, 2006)

This project has me intrigued. What is a good source (online or otherwise) for membranes and membrane housings? 


I suspect that this will be most difficult part to procure in addition to the high pressure pump.


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## Martinini (Jun 18, 2008)

Membranes can be had here Seawater RO Membranes Elements for Seawater Desalination WaterAnywhere RO Seawater Membranes


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## Martinini (Jun 18, 2008)

Something elese I have discovered is that you can find a lot of the componants needed on Ebay for a fraction of the cost.


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## RichH (Jul 10, 2000)

night0wl said:


> This project has me intrigued. What is a good source (online or otherwise) for membranes and membrane housings?
> 
> I suspect that this will be most difficult part to procure in addition to the high pressure pump.


Midwest RO Reverse Osmosis and Water Filters and Membranes in Illinois is probably the cheapest. Probable best and most compact hi Pressure pump is the Giant Model 218 @ $350.00 (brass head not bronze).


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## geraldartman (Apr 9, 2007)

Glad I sail the Great Lakes. $70 filter will handle a couple of hundred gallons. Have to hand pump though.


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## Cruisingdad (Jul 21, 2006)

GREAT thread, guys. 

- CD


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## RichH (Jul 10, 2000)

geraldartman said:


> Glad I sail the Great Lakes. $70 filter will handle a couple of hundred gallons. Have to hand pump though.


But you have a 'special' problem on the GLakes .... cryptosporidiuim - a very nasty oocyst that can be easily taken onboard from water distribution sources that dont have the proper filtration on them. Crypto is resistant to chlorine sanitization ... so you really have to be sure to filter any 'questionable' water you take onboard - with a 'FDA certified' filter that is 'validated' to remove 'cysts'.


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## Omatako (Sep 14, 2003)

night0wl said:


> This project has me intrigued. What is a good source (online or otherwise) for membranes and membrane housings?


Actually membranes are not difficult to source. Along with the other suggestions, try here

FILMTEC Membranes

Coincidentally, I am busy building a water maker as we speak. I have a piece of stainless tube and the membrane and am now busy with machining the end pieces to locate the membrane, provide the water/brine seperation and attach the hoses for water in and out.

I have a 110v inverter and a genset (not in yet) so I will be running off a 110v motor for the pump. This gives me the best of all worlds. I can run on shorepower, I can run it while I'm motoring (large-frame alt puts out 180amps) or I can run it off the genset.

As far as raw water supply, I have thought about teeing into another skin fiitting and for reasons already espoused on other posts, I'm nervous of the possibility of other appliances drawing water away from the pump because the engine and/or genset will probably be running at the same time. The answer for me is to T off one of the head inlets.

Good post. Thanks


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## Cruisingdad (Jul 21, 2006)

The rule of thumb on water makers is to put the thull as far forward as practical to lessen the liklihood of contamination - like from the sink, for example or God forbid the head.

- CD


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## GaryHLucas (Mar 24, 2008)

That is a good article, I build RO systems, for wastewater not clean water. A couple of comments.

I prefer the BlueWhite flowmeters over the Dwyers. They have union ends that make swapping or cleaning the flowmeter much easier. They also come in elbow end style that is very easy to mount.

The Wanner pumps mentioned are very good. They are hydraulicly driven diaphram pumps in an axial configuration. All the moving parts run in an oil bath and they are very tolerant of abrasive or aggressive fluids. They are MUCH quieter than piston pumps, and have much less vibration. Both very good on a boat.


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## GaryHLucas (Mar 24, 2008)

I'd like to add one other thing about safety. The PDF file showed two Y valves used in the feed and permeate lines. Those are good choices, but it is important to know why. The author mentions that the brine line after the control valve and the permeate line are both low pressure. That's true, only if nothing ever blocks them!

I've had three high pressure RO explosions in the past five years. One because someone plugged a drain line that the relief valve was plumbed into. One because two 2-way valves were used instead of a no-center-off 3-way valve. Finally, because the permeate pipe froze, and so did the two relief valves!

So don't be tempted to go adding lots of 'convenience' valves to this design!

Gary H. Lucas


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## Omatako (Sep 14, 2003)

Gary

I intend to have my brine line going out above the water line to prevent it cloggng with sea life etc and to save having another below waterline skin fitting.

On the permeate line I intend to build a stainless manifold. I have three tanks so I want to have the manifold equipped with obviously an incoming line from the membrane cylinder and then four valved outlets. One will go to a sampling tap to be able to ensure that the water is good before sending it to a tank. The other three will go to each of the tanks so that I can fill the one that needs it.

On this manifold I will also put a relief valve that will vent at about 200PSI to prevent any pressure build up if something goes wrong downstream or if all 4 valves are accidentally turned off.

Is this OK or am I over-killing the thing?


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## GaryHLucas (Mar 24, 2008)

I'd try to do it without the relief valve, by running the permeate into a vented tank or open top PVC standpipe, then gravity flow through 4 inexpensive plastic valves that will see no pressure. You want to maximize your clean water production and backpressure on the permeate lines always reduces it.

Another interesting thing. Membranes will produce poor quality water if run at too low a pressure. You can get water out of a membrane at almost any pressure, but the water will be the highest quality when the pressure matches the membranes design pressure.

If you take your boat up a river into fresh water you'll find that the RO will produce a lot more permeate at a much lower pressure, like 300 psi. You wouldn't want to run it at 800 psi because the flux rate (permeate flow) would be way to high and you'd run the risk of fouling the membrane.

One last thing. When the differential pressure from the feed end to the discharge end starts to increase you have fouling going on. The membrane should be cleaned immediately, or you run the risk of never being able to clean it. If you clean it and the differential pressure is still high you didn't get it clean, and another immediate cleaning is warranted. Often you need to change cleaning chemistries, because the foulant may be something you weren't expecting. Membranes have a bad tendency to get into a death spiral. One bad cleaning leads to another until the membrane is shot. On a boat you are talking $100 to maybe $700. On our systems it is more like $10,000!

Gary H. Lucas


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## Omatako (Sep 14, 2003)

GaryHLucas said:


> I'd try to do it without the relief valve, by running the permeate into a vented tank or open top PVC standpipe, then gravity flow through 4 inexpensive plastic valves that will see no pressure. You want to maximize your clean water production and backpressure on the permeate lines always reduces it.


Gary, seems my "layout" wasn't that clear. The permeate would flow into the manifold and four valves (taps) which would allow me to direct the flow (not under pressure) to where I want it. The relief valve is simply to ensure that I don't accidentaly pressurise the inside of the mambrane by shutting off all 4 valves.



GaryHLucas said:


> One last thing. When the differential pressure from the feed end to the discharge end starts to increase you have fouling going on. The membrane should be cleaned immediately, or you run the risk of never being able to clean it. If you clean it and the differential pressure is still high you didn't get it clean, and another immediate cleaning is warranted. Often you need to change cleaning chemistries, because the foulant may be something you weren't expecting. Membranes have a bad tendency to get into a death spiral. One bad cleaning leads to another until the membrane is shot.


The system I am contemplating has only one presssure guage - on the brine line at the output end of the membrane (to adjust the pressure on the high pressure side of the membrane). How do you know that a differential pressure exists? That implies two pressure guages. Please explain the setup as you see it.

Thanks


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## GaryHLucas (Mar 24, 2008)

I understood your layout, I was just suggesting that the manifold could be an open vented tank so you don't need the relief valve. The flow rate is so low it would never fill the tank unless your lines were really tiny.

Yes, I would put two pressure gauges, one on the feed end one on the concentrate end. You want some pressure drop across the membrane. If there isn't any pressure drop then there isn't any turbulence and it will foul rapidly. There is a minimum GPM through flow for each size and type of membrane. So the two gauges tell you that you have sufficient flow, and then that the membrane is fouling.

Gary H. Lucas


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## Cruisingdad (Jul 21, 2006)

RichH said:


> Midwest RO Reverse Osmosis and Water Filters and Membranes in Illinois is probably the cheapest. Probable best and most compact hi Pressure pump is the Giant Model 218 @ $350.00 (brass head not bronze).


I am researching building my own watermaker. If I do it, I will detail the process here and what I bought and how I did it.

One question: On the WM's you have helped put together, did you use a electric motor or engine driven?

Also, who would you reccomend for the membrane? I have a couple of sites I am looking at, but curious who has bought/has experience with them?

Thanks.

Brian


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## Cruisingdad (Jul 21, 2006)

Open question:

I have a bit of a problem to work through.

I have a 3.5kw generator. That would be my preferred method of running the watermaker. However, I will be limited to 26 amps max. In reality, I should keep it under 23 or lower, with lower being mych preferred. I have the HP on my main engine to run a watermaker, but unfortunately, not much room. So the preference really would be a Generator run watermaker.

So, most of the watermakers call (ideally) for 3-4 gpm with 1000 psi. That will be difficult to obtain and stay under my parameters as I suspect that will take a 2.5 hp motor. As such, do you (G LUcas or Rich H or others) feel that I can run a 2.5 X 40 with 3-4 gpm and 800 psi? I hav been told, not sure it was reliable, that 800 psi was the test pressure for most membranes and should be fine.

Also, regarding motors, I have several to choose from. Rich suggested a Giant motor which only pulls 17.5ish amps. Another option might be this Baldor EL1405T:

http://www.baldor.com/products/specs.asp?1=1&page=1&catalog=EL1405T&exact=1&product=AC+Motors&family=Premium+Efficiency|vw%5FACMotors%5FPremiumEfficiency&winding=36WGY526&rating=40CMB%2DCONT

It is a premium efficiency motor and might be a better choice as it has a lower draw, but am curious what others think of it??

So there is a start. Thanks for everyone's opinions.

Brian


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## Cruisingdad (Jul 21, 2006)

Another question on watermakers:


If I reduce the GPM, that will only reduce the output, right? If I want max output, I must maintain max GPM? But if my putput drops to say, 2.8 gpm versus 3-4, but I maintain my 800+ psi, I will only make slightly less than rated water, correct?

Brian


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## GaryHLucas (Mar 24, 2008)

The 800 psi is not a test pressure. We are REVERSING osmosis, the natural tendency for a liquid with a low concentration to permeate through a membrane into a higher concentration thereby diluting it. We need to force the liquid in a high concentration (seawater salt) to pass into a low concentration ( the clean permeate) Osmosis is so powerful it pushes water from the roots to the tops of giant redwoods!

So you need the 800 psi to overcome the natural osmotic pressure of seawater. If the pressure is lower permeation will happen but more salt will be passed through too. RO elements are never 100% filters. They may be 99.8% for seawater at the right pressure. On glycol they pass 7%, and we use three stages to get 7% of 7% of 7% for the final discharge.

The rate of permeate discharge is not related directly to the feed flow in GPM. Slowing down the flow using a smaller pump at the same pressure will produce the same permeate rate, for a while. The concentration of salt left behind will be higher, more likely to precipitate instead of staying in solution, and there will be reduced flushing, all leading to fouling quickly.

Baldor premium efficiency motors are very good, and increasing efficiency to get a lower amp rating is a good idea and not too expensive at this size motor. I don't work with single phase motors much any more. If this were a 3 phase motor I'd put a soft starter on it. That would allow you to use almost all the horsepower of the generator because it would be easy to start he motor. You might look at using a 3 phase motor (cheaper, lighter and more robust) with an inverter GS2-23P0 $300 from AutomationDirect to run it from the generator. You could then ramp up the motor gently and exactly match the required pump speed too. They have great tech support, you could discuss this with them.

Gary H. Lucas


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## GaryHLucas (Mar 24, 2008)

By the way, run that motor on 230 Volts if your generator produces it! Otherwise you'll drawing twice as much current on half of the generator windings and that will surely cause you trouble.

I once went on a trouble call (industrial electrician in a former career, this is #3) on the biggest sump pump I've ever seen in a basement, a 4" discharge! It was overloading the lady's backup generator every time it kicked on. IT was 120 volts, but the generator was 120/240. I installed a 240 to 120 volt transformer and used 240 from the generator and the problem was solved.

Gary H. Lucas


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## SoulVoyage (May 9, 2010)

Anybody have any experience using the *Pur 35 *watermaker? I would be interested in this one, because it can also be used in manual-mode, albeit FAR slower and lotsa work. I think the sell for $1800, but much less used...just hard-to-find used.


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