Making your own water-maker

[Jolly Roger]

One of the last items I want—before setting off on our maiden voyage after a four year refit—is a water-maker. I know they incorporate a lot of fancy items, but I still find them expensive at around $4000.
There are a few very informative articles on the web, about buying the equipment and building your own, and I would like to ask a question about the pressure pump in particular.
I have been given a perfectly good pressure washer, run off a Briggs and Stratton gas engine, and I wondered if I could incorporate the pressure pump into a water maker system? It delivers 1.9 gallons per minute at 2000 PSI.
I could disconnect it from the motor and believe I could fit an electrometric clutch, then run it of my 36hp generator, with a pulley to give the correct revolutions and pressure—whatever that should be.
Has anyone ever done this? for me, there would be only one reason to do it—money!

[texwards]

I don't have any firsthand experience or answers to your question, but have also been looking into this. You may have already come across this, but these seem to be informative 'how to' articles:
Good Old Boat -
In Jan 2003 there was a thorough walk through and explanation.
Another 2 part article May and July of 2010. This was slightly different, but also good - with additional useful info on sourcing the parts.

Informative overview:
Watermaker: Doing It Yourself | | PassageMaker

[Jolly Roger]

Thanks for your reply Texwards: The Steven Anderson article is very comprehensive, if a little daunting.
He discounts domestic pressure washers on the basis they are designed for fresh water, not saltwater, and I hadn’t thought of that. I think I will forget it and bite the bullet for a purpose made belt driven pump off my generator.
The generator would need to be run to produce 120 volts to drive an electric pump anyway, and will produce more gph than an electric pump through two 40” membranes.
Strangely enough I have three articles coming out in “Good Old Boat” next year, about things I’ve done to my boat, and it is a great magazine for do-it-yourselfers.

[ColdEH]

Hi Rodger.

If you can, try to find yourself a Hydra Cell D10 pump made by Wanner, I got mine on Ebay for a really good price.

Pumps for water-makers give you more trouble then any other part so you should get the best one you can and forget about it.

Most pumps have pistons in them , no mater what they are made of , pistons have rings , why? To stop the oil from getting in the water, and the water from getting in the oil. But believe it or not it still happens . Your membranes are very susceptible to oil and will give up the ghost eventually because of even small amounts . So get a pump that keeps the oil out of the water , get a Hydra cell and run it at a third its capacity , they are cheap and easy to repair if the damn thing ever breaks. They use a swash plate just like your domestic water pump , just at higher pressures and volumes . These pumps are perfectly suited to an engine drive system.

The most important part of your water maker is the pump.

http://www.youtube.com/watch?v=C_MYa...WEihdLf7Hjer9w

Regards

[Lars_L]

A watermaker have quite high pressure on the membrane side, maybe 6-7 MPa. If you have a system that use that pressure for making pressure on the incoming water, that system will not use so much energy. Less than 5 Wh/l water. Spectra have such a system.

You can built a system with:
Spectra Ventura 150 watermaker.
100 W solarpanel.
60 Ah battery.
And get at least 50 l water per day.
I’m about to build my own watermaker, but that shall be a small system with a capacity of 2 l/h, but it shall take less than 10 W.

[Pauls]

Brent Swains book has plans for a homemade watermaker. A number of them have been built, the owners seem happy with them. The book title is "Origami Boat Building". It has a number of interesting ideas.

[Nadezhda]

Try this PDF....http://www.westward-ii.com/PDF's/How...watermaker.pdf

[SV THIRD DAY]

We help folks wanting to save money build their own water makers all the time. Get the help of an "expert" who can steer you around the myth and reality of how to build a good reliable unit yourself and save a few bucks at the same time. Will you save some money...sure, but will be be as much as you think? No...but it's also a pretty fun project.

Here....download a copy of our 20 gallon per hour water maker manual to use as a template and have some good operational procedures.

www.cruiserowaterandpower.com/uploads/sm20.pdf

If you want an engine driven manual, just shoot me an email and I can first try to talk you out of it...and then if you still want to go that way, I'll send you a copy of the manual.

Why would I try to talk people out of an engine driven water maker?
Experience. I've owned one and watched the installation disasters of people trying to mount the pump to their motor and have an epic fail.

[sailersteve]

Theo i do not have time right now to read the whole article. RE; Watermaker ; Doing It Yourself / / PassageMaker. I found a problem with the PVC manifold . PVC can not be used for potable water period. PVC is to be used for DRAIN/WASTE ONLY. CPVC is potable water safe and will come in 3/4" w/ 1/4" reducer's available . Plumber retired . Sincerely sailersteve .

[1affiah]

Not So, Sailor Steve: I think you are referring to DWV (drain,waste,vent) class of PVC, which are not rated for pressure. Pressure classes of PVC have been in use for decades, ie: Schedule 40, Sched 80. CPVC is for hot as well as cold water, will work fine as well.
Sailor Larry, Retired Salesman

[1affiah]

PS: You can't go wrong following Rich's advice!

[sailersteve]

Thanks 1affiah . I guess i was thinking DWV class of PVC. The thing is , make sure to use a class of PVC that is potable water safe , some might not know to make sure . Sincerely sailersteve.

[1affiah]

Not sure what the manifold is for, I built mine from e-bay parts and stuff from Rich. I used 3/4" bronze 3-way valves on the seawater side so I could power a deck wash with the low pressure boost pump, and 1/4" plastic 3-way valves w/PE tubing on the outlet side so I could direct the output water to the sample tap or tanks. No PVC on the intake or hi pressure sides.

[sailersteve]

The manifold in the article was for gauges , low intake water pressure shut off etc. I guess i've still got a lot of reading to do to make a watermaker that cost less then my little boat. I'll be waiting on the patent rights to be opened up ( 2015 ) to competition of one of the major brands . Maybe some already rich sailor will think need more then greed !

[Jolly Roger]

Having read all the do-it-yourself watermaker articles I can find, and spoken to a few suppliers of the various equipment, I have come to the conclusion that at this moment in time for us, we would be better to spring for a complete turnkey operation from one manufacturer.
I am certainly not afraid of taking on big jobs. You can read that on nearly every page of my website, for the development of my boat. I changed it from a ketch to a schooner for goodness sake! But we want to get going in January and I don’t have time to pick and choose all the different parts which make up a good watermaker.

Another thing which struck me, talking to different equipment suppliers; if I buy individually, there are different warranties, and what if a particular part breaks down? Will it be claimed it was someone else’s gear which caused it, or it was not compatible?
Buying from one manufacturer, I get a complete three year warranty on all the equipment they supply.
The only downside will be price, which I think will be about one third more. So I am now looking for the best value for money for my specifications, from about four different manufacturers.
Thanks for all the responses and suggestions everyone. This forum is the best.