Affordable Watermaker

[Brent Swain]

You can build your own watermaker using a pressure washer pump.A General pump model TT9111 3gpm works well and costs around $325 CDN. The standardised 540 gallon a day membrane fits perfectly in a 2 1/2 inch stainless sch 40 pipe , which makes a great pressure housing for the membrane. You can buy type 316 stainless pipe at scrapyards for $1.50 a pound. Friends have been using this arrangement since 1998 with no problems. Watermaker pumps are built for around 1,000 PSi whereas pressure washer pumps are built for 3,000 PSI and are much more solidly built. With 540 Gallons a day output you get plenty of water to flush them out properly. With the 40 gallon a day ones you have to run them for nearly an hour to get less than two gallons of water, then for another hour to get enough water to flush them properly, which is why they tend to not get flushed properly, and why they tend to have so many problems.
Info on watermaker arrangements is readily available on the internet, just substitute the parts mentioned. My book, "Origami Metal Boatbuiulding" describes the above watermaker in greater detail.

[troppoboat]

Hi Brent do you know what pressure the membranes operate at?
Regards Shane

[capn_nik]

how did you know that was the question I was going to post..(can I build my own watermaker)...do you have any web links for the setups you mentioned? I presume I could use some sort of y valve and use it to scub my hull too? thanks again for posting, I am definitly the make it yourself type of guy. Why pay more for poor craftmanship when I can do it AND understand it when I'm done!

[irwinsailor]

In the Mag. "Good old boat" about 18-24 months ago they had a feature about making your own watermaker.

[goingsoon]

Love this web site, a friend and I have been batting this same idea around for a couple of years and will make one after reading your book, will let you know how it works out.

[MB]

Can it be set up with 12 volts DC?

[Alan Wheeler]

The 12V part is going to depend on how easy it is to replace the AC motor. Depends on the design of the pressure pump as to this bgeing possible or not.
I would think the easiest solution is fitting a DC/AC inverter, although maybe not cheapest.

Hey Brent, when you say "your Book" is this something online, or do we have to buy the book somewhere. A hint of what direction to look woiuld be good.
Thanks

[exposure]

I think his system is engine driven and probably has too high a power consumption to be run by an electrical motor on board. But with 540 gallons/day equal to 22.5 gallons per hour, you could make enough water for a some days with one hour of running time. Since I have an engine driven fridge this might work well for me. Perhaps I will order the book. How is it available?

Woody

[exposure]

Rough calculations for the pump are about 3hp required. This is over 2000 watts or over 150 amps with a 100% efficient motor. Even if I am off by a factor of two, 75 amps is not practical for an electrical system on a boat. It must be engine driven.

Woody

[BC Mike]

I have Brent's book but it does not describe the water maker, my book must be an older version. BC Mike C

[Brent Swain]

For the latestedition of my book with the watermaker building instructions, etc, please send $20 plus $5 for postage $10 for overseas airmail postage to 3798 Laurel Dr, Royston BC Canada V0R2V0
The membrane uses around 750 psi in the tropics and around 900 psi in colder waters.
Brent Swain

[Badsanta]

there are several listed on EBAY with part lists and instructions. I have not bought one and maybe they are youre, I dont know, but intresting and another source for info. Cheers

[scotte]

I stashed the following link away for future reference, and figured it was worthy of passing around. This has some of the best writeup and design info on building a DYI watermaker I've come across. Hopefully it's useful to someone...

Watermaker

[Badsanta]

very nice, But I'm still lost. still over my head.

[jheldatksuedu]

I've been toying with an idea on a watermaker. I saw a device called a waterlog, you tow it behind the boat, it contains the RO element and a propellor driven HP pump, and fresh water trickles into the boat. One problem is that it sounds like very expensive shark bait to me. I've been considering building up a system that involves towing a propellor driven low pressure, higher volume pump and having and pressure multiplier device and the rest of the system on board. I'd be happy to hear responses and other ideas.
With the mention of the pressure washer pump maybe I will rethink and go engine driven. If anybody has more info on the source and part number for the RO element mentioned in Brent's book please pass that on. I can't seem to find max pressure differentials that different elements can stand. I've been wondering if you can disassemble a home element and beef it up or reengineer it to withstand higher pressures and have a very inexpensive very low volume element.

Scotte, thanks for the link. Jon Held