DIY Watermaker vs..brand name version.

VERSION 1


 Watermakers eh? Well not wanting to go to docks all the time or not wanting to plan trips around docks or other land based water sources is the main reason, and cost is usually the main reason not to. Our first was a Katadyn 40 E survivor model that I bought from the Binnacle store in Halifax. The reason being it was the best price I could find in North America, offered free shipping and only 5% sales tax. No brainer there. I got it and installed it and we are still using it 5 years on with no problems.
 Katadyn 40 E

I also got the fines filtration and rebuild kit with March lift pump. This is a great little machine that with adequate care will provide trouble free water for two people that will run off of solar power alone taking only 4.5 amps per hour. It is a noisy thing but not horribly so like the constant drone of a generator, but this is a personal opinion and varies with location and boat size. Ours is under the cockpit and so difficult to conceal the sound. However running while motoring offsets this negative so we were happy. On longer journeys ie; all summer, the necessity of running it every day to keep up was tough. We like to anchor for 2-3 days at least without turning the engine so if the sun don't shine our power supply begins to wane quite rapidly. We figure we need ten gallons per day so the machine has to run 6 hours every day minimum. We looked for creeks on a regular basis. If the machine was quiet I could see running it for 16 hours every 3 or 4 days, drawing 40 amps out of the battery bank plus the solar if sunny..but just couldn't tolerate the noise for that long, and didn't want to leave it running while away from the boat, although did do that a few times, but then you worry. Now we have a reliable back up. I use it when single handing for drinking water mainly on short excursions of two to three weeks. When we used it on a three month sojourn it was a constant background scenario ie: making or getting water. Conserving, scouting creeks for laundry, hitting the docks. I did enjoy the creeks, though.

VERSION 2

This year we decided to get a bigger output machine, and thus began to investigate the DIY schemes that I had been reading about for years, as well as looking at the production models for 20GPH machines. After much cogitation I realized that I was not up for the $10,000 price tag on a new Spectra. Or the $7000 to $8000 for an engine driven model. There are quite a few out there and some are quite complicated ie: lots of electronics. I went with the simplest method I could find which is a   pressure vessel a  membrane   and a  pump.  ( there are many pumps..some use the General Pump WM 2515 which is stainless and cost about $1000. The one I use is bronze for $275). Then I had to figure out how to power the pump. Initially I figured to go 12 volt, but that would require very expensive motor and switching stuff and more solar power etc. Then I thought 110 volt, but I would then need a good inverter and all the cabling etc. which would push the cost as well. Next up was a 110 volt motor driven by a Honda or similar generator. Again cost and storage and gas. Nope. Then I looked at engine driven..the so called 'Hail Mary' install because of hidden costs, bad installs, etc. Our engine compartment is by no means easy to access for this sort of thing, it is all heads in the bilge sort of stuff, and there is precious little space. After much fooling around though I found a spot. I would need a pto shaft to fit the front of the crank fan. I called the Betamarine people to see if they had shaft extensions for my engine..they did, and if my plan would negate the warranty..it would not. So I ordered the stub shaft and drive pulley from Gartside Marine in Sidney. They had a few problems getting it in from the UK but eventually I got it and installed it so that I could then design and build the pump base and get it glassed in. Thinking of how to mount the pump was complex. Most of the info online suggests that the pump must be ideally attached to the engine as like an alternator to avoid stress or extra gear like idlers or having to remove belts each time you make water. After much looking about I saw that I could mount the pump dead center below the crank pulley which is the best place to hard mount one as the engine movement is pretty well limited to sideways rather than up and down movement due to torque so having the pulleys aligned like that allows the v belt to move side to side and absorb the torque. The engine runs pretty smoothly and so this seemed to be an acceptable method. To work then...I needed to get an electric clutch .( about $225  ) Then I would need to mount the assembly and line it up under the crank pulley. I needed to build a base for the high pressure pump that would allow for belt adjustment.

I used some aluminum plate and angle for this using two pieces of flat 5/16 thick plate to attach the pump and then the base plate which is a simple electric motor adjustable base...$40 at any motor shop( or less ). The metal was about $40 as well from a metal shop.  (I ordered the big parts from USA. Prices and ordering vary..you may find these parts in Canada for a good price if you look around or can buy wholesale. I got the rest of the parts locally..hose and valves pressure gauge and flow valve. Some in stainless steel which is considerably more expensive. Overall the parts ran about $3000. I made some mistakes of course which pushed the cost up, and could have likely found cheaper parts, but overall the cost was acceptable for a 20 gallon per hour watermaker. )

The pump with attached clutch on the base...

Some drilling and bolting and some fitting to get the clutch centered and this assembly is ready to go. All work done on the boat as I don't have a shop...The spot where it will sit once held the fuel tank for the diesel stove which had to be moved to a spot under the sink..which actually turns out to be a great spot for it. |I ran a line from the main fuel tank so I can fill it with the primer pump.

Once the paint was off I could glass the pump assembly in. Took a few placements and straight edge alignments but eventually the assembly was in place and glassed in.

This shot above shows me lowering the pump onto the glassed in base. It weighs about 30 lbs and is awkward to maneuver while heads down in the bilge, so the block and tackle made that part easy. I lowered it onto the bolts that I had set in place by tapping the holes for 3/8 bolts. Below the assembly is wired and belted. You can see the shaft extension bolted on the red crank pulley. The blue cast iron pulley and bushing was $50. The stub shaft was expensive coming from Beta, you could likely have one done at a machine shop for less. There are many variations for mounting and driving so each install will be unique. I was able to build the unit so as to be easily removed without detaching any hoses or major renos. I move one fuel filter without taking the lines off and the whole unit comes straight up via block and tackle suspended from the cabin top hatchway.

Below is the improved housing that I had built as the bottom only mounting was not strong enough causing the vibration to snap one of the bolts. This mount totally encloses the pump with four retaining bolts, 2 up and 2 below with side struts that hold the pump tight, The whole enclosure then bolted to the base which is adjustable. As I needed only to have sides and top welded on this was inexpensive. So far the water production has been greater than expected with approximately 25 gallons produced in an hour running at 1400 to 1500 rpm and 800 psi. The TDS measured 48ppm.

In the above picture the high pressure line is top. The high pressure SS elbow with HP SS swivel..plastic plug is to keep dirt out while maintenance performed. The low pressure SS elbow and SS hose Barb on the lower intake line. 

Above shows the adjustment bolt on the lower electric motor mount.

Get an idea of the size. 

Both pulleys are 7 inch diameter.

Since this I have installed a tensioner ..a Rosta R18 to ease the tensioning process and allow for simple disconnect by removing the belt. I do this in an abundance of caution. I could leave the belt on and freewheel it as does every a/c unit in every car but I figure that if I make it very easy to remove then why not decrease the number of moving parts. The Rosta tensioner..blue thing..is simple to adjust.

Short vid of the finished installation. Smooth running with just a bit of tension. The Rosta device works with stiff rubber instead of wound spring and is very easy to add tension. Once in place the tensioned arm maintains the belt tension while allowing for any engine movement to be absorbed by the rubber. These devices are widely used in industrial applications where frequent variations of torsion will wear out belts or equipment due to over tension or slackness of the belt or chain drives. Here it works as a very quick and easy belt on belt off and smooth run. |Once set up to the tension needed the belt can be removed by hand without tools in seconds. Adjusting tension is done by loosening the center retaining bolt then with a large wrench (1 3/8 ) bring up the tension to what is needed and re-tighten. These can also be used with alternators.

The pressure vessel found a spot right above the smaller Katadyn unit.

The lift pump which feeds seawater to the high pressure pump is seen here..it is a Jabsco mini water puppy which I got for $100  just because it had been on the fellows shelf for 30 years. Haha it works just fine. New ones run to about $400 or so. I used some plastic valves from the hardware store for the low pressure feed lines..cheap and easy. I used plastic conduit clamps to hold the hoses.

All the lines go to a spot between the stairs and the fridge. It is a little messy and I will be changing it up this winter, but for now it fits in there and provides space to work once the steps are out of the way. Many people have mentioned pulsations from the high pressure pumps and potential for chafe and whatnot. Pulsations are usually caused because of cavitation in the high pressure pump where there is not sufficient volume of feedwater supplied so the high pressure pump cycles air thus causing a banging sound and jerking of the hose. The  pump the maximum output pressure is 1500 psi at 1750 rpm. The membrane max psi being 1200 and the operating pressure for normal seawater RO being 800 psi, I have found that I can easily make water to spec for the membrane running at 1100 rpm. The pulleys I use are 1:1 ratio between the crank pulley and the electric clutch so it is quite simple math to achieve the output. The pump is 3 gallons per minute output at the rated max. I am feeding it with the mini puppy which puts out 1.8 GPM and there is zero pulsation with this pump. It runs very smoothly. I run water via the feed pump until the system and high pressure pump are loaded then engage the electric clutch at idle speed 850 rpm and then bring up the engine revs and adjust the flow control valve until the pressure gauge reads 800 psi. I run the product water into a pail until it has flushed all the old permeate out then switch it to my holding tank which takes 14 gallons. I can then transfer that water to my main tank which is 55 gallons and as well can draw the made water to the galley sink through a carbon filter for good tasting drinking water. Below you can see the various lines and valves...

This is showing the mess of lines which include the test lines from both watermakers, the pickling hose uptake and concentrate diversion lines as well as the lines to the filters..30 micron and 5 micron. At the top you can see the high pressure line coming to the gauge and then the high pressure stainless steel flow control valve ($200 from hyseco).These high pressure lines are way overbuilt, and you can get by with a lesser and cheaper type of line that is rated lower. Stainless steel is the gold standard however you can buy many regular fittings for the cost of one ss. For example SS 1/4 inch npt swivel is about $60 cdn. High carbon is $2. So I am about 50/50 with some of each. I needed BSP adapter fittings for the pump because it is built in Europe and those fittings are both expensive and special order from most hydraulic shops in SS. They carry the regular steel though, usually..Newline or Greenline. The quick connect seen there is to facilitate changing to the 40E watermaker and for adding the pickling solution. When using the 40E I do not need the lift pump and it is too much for the 40E to suck raw water through that apparatus so I can switch the intake directly to the prefilters for that machine.
This next shot is with the stairs in...

Tight squeeze but so far all good. This project has been a steep learning curve for me although overall I feel good about it. I know how it all works and can replace each component without much difficulty should the need arise. Now we have plenty of water for cleaning showers laundry etc. at no additional costs besides filters. The system is not automatic for sure, I need to monitor the process, need to flush afterwards, and need to pickle from time to time when we have gone to dock, but that is really nothing. Pickling I use potassium metabisulfite or food grade glycol with absolutely no additives in it like alcohol. You can get the glycol at RV stores or usually Walmart. The metabisulfite I get at the grocery store in the wine making aisle. You can buy it at the chemists also. Sodium or potassium don't matter.

Since over wintering  2020 spring and fall  I no longer use the chemicals but prefer glycol. The reasons are that it is easier and works well. After flushing with good low TDS product water first, then filling the system with food grade glycol with o% alcohol. I re-activated both systems with the Katadyn unit being pickled for 14 months to no ill effect. I had one small issue with the larger element when the TDS rose to a quite high level, greater than 1200 ppm..I thought I had perhaps shocked the element due to cavitation when I had revved the pump higher than the feed pump could supply the HP pump. As it turned out I had allowed my rinse water to gradually build up TDS by reusing it. Once I dumped it and used good low TDS water to rinse the system the TDS came back down to under 100ppm. Moral being..use fresh rinse water.

Now summer 2021 and have returned from a month out. Watermaker working well. We don't worry about water these days. I always flush the system after each use and change the filters. The filters clean up with a few dunks in Bay on the end of a rope and hang in the sun for a few days to UV the bugs. The filters last a long time. After the cruise I pump the system full of 'Absolute Zero' no alcohol food grade glycol. Make sure it is the no alcohol one as they sell the same brand name with alcohol right alongside. I use a gallon and that cost $12 cdn at Walmart.

I finally got around to moving the filters and the controls.

this gives more space around the stair and puts all but the flow valve in the cubby. Still allows for the water tank to be easily removed for any serious maintenance in there. Both watermakers are functioning well and over winter with no ill effects when pickling with alcohol free food grade waterline antifreeze. I actually hadn't used the 40E for more than 18 months but it came back online with little fuss and produced water with a respectable 250ppm of nacl. The bigger engine driven watermaker still comes in with less than 100 ppm.

Flushing with fresh water and changing the filters after each use is important. The filters have lasted        through  two seasons actually with two sets in use cycling them through use, rinsing and hanging in the sun.