watermakers from Jetwashers

bazobeleza

bazobeleza

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Being a Yorkshireman, inveterate tinkerer and all round tight git, I have decided to build my own watermaker. I have investigated this on the net its well documented, I find I can build a 40gph one for for about £1500 but........ I then heard about a dutch lad selling plans for using a jetwasher for the base but of course he wants his palm crossing in Guilders before he'll send you the plans.

My question is has anyone recently made a watermaker using a Karcher or similar and how did it perform.

I have a Karcher K7 that is surplus to requirements and needs a new hose has a performance spec about 3.75hp motor and 550l/hr (120 gph) at 2300psi so I think with a different (lower) pressure regulator at 1500psi the output could be increased probably to around 200 gph and a 12% conversion rate would give a watermaker of 24gph capacity

The mechanics of construction appear to be straightforward high pressure plumbing. There does appear to be a problem buying the RO pressure vessels in the UK as I've not yet found a supplier.

Input power isn't an issue, cost however is. Any advice will be gratefully received particularly on sourcing the RO bits in the uk.
 
I'm not sure that Karcher motors are designed for continuous operation - I've certainly experienced thermal cutout on mine during fairly heavy use. Apart from which, I don't think the pumps are very durable, especially if pumping seawater; it would be a shame to go to the trouble of building a watermaker and then finding that you have to rebuild the pump every few hours.
 
I've seen this proposed before and seen statements that the pumps corrode with salt water, also seen suggestions that if you produce lots of fresh water you can flush the pump with some of the fresh, doesn't need to be musch or at high pressure and gives the RO a flush as well.

Try Atlantis Marine in Plymouth for RO parts. They were very helpful each time I've called.

My local goods vehicle high pressure hose people were also very helpful.
 
A Karcher type pump ( medium duty one ) outputs at around 20 bar, the pressure required to get a RO membrane to work with salt water is 800 to 1,180 psi or 60 to 80 bar.

If you buy one of the High end professional pumps from Karcher you end up paying the same as a proper pump and it's still not a stainless steel one.

The high pressure pump is the heart of the system, best to bite the bullet on it's purchase.
 
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yes, i have a karcher system running on my boat.
it gives me 60 l/hr, am thinking of upgrading to 100 l/hr (second membrane).
Power consumption is either 1.3 kw by generator or 120 amps by inverter.
Noise is an issue as well, so putting the karcher in the engine compartment is a good idea, but still...
Costs around 1.500 Euros, no serious problems so far.....
Regards
Rainer
 
My book has the instructions for building a 540 GPD watermaker for under $900
I use a General TT911 pressure washer pump, 3 GPM, with ceramic plungers, around $300CDN.
Works well, and has for many years.
 
Brent Swain said:
My book has the instructions for building a 540 GPD watermaker for under $900
I use a General TT911 pressure washer pump, 3 GPM, with ceramic plungers, around $300CDN.
Works well, and has for many years.
Click to expand...

I can tell that you've been considering your reply very carefully, for over 4 years in fact, so I'm sure we're pleased you eventually decided to share your info.
 
Haven't been here much, having a life beyond the internet ( can you say "Cruising?")

pvb said:
I can tell that you've been considering your reply very carefully, for over 4 years in fact, so I'm sure we're pleased you eventually decided to share your info.
Click to expand...
 
Few people I know have build them out of an Karcher PW pump and one is on his third year , another one had to replace it after two years .
I build mine from an Cat 277 pump last year , I am getting around 110 lts an hour depending on Temp .
Personally I think if you are going to build one it's worth spending that bit more on a good pump .
 
I've been looking into building one from an airless paint sprayer.
These run at very high pressures (2000psi+) but can be quite small pumps at around 5-800w, so easier to power from a battery bank and inverter.
Would be curious to know if anybody has tried this yet?
 
I met "the Dutch guy" about five years ago in the Cape Verdes and again in the Antilles. He showed me around his Karcher-based watermaker, which was the prototype for the one for which he sells plans. As far as one could tell it worked well and reliably (the installation was then about three years old). It was bloody noisy, though. (The 2kw portable Honda genny he used to run it was somewhat quieter.)
 
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Membranes: not many manufacturers but DOW builds them under the name of Filmtec. If you can find a distributor in UK, let me know...

Getting mine from the US.
 
Monique said:
Membranes: not many manufacturers but DOW builds them under the name of Filmtec. If you can find a distributor in UK, let me know...

Getting mine from the US.
Click to expand...

Desal Supplies in Rochdale sell Dow Filmtec membranes, about £180 + VAT + Carriage for the SW30 25-40 commonly used in boat watermakers. Google should find them easily.
 
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