Updated on September 21st, 2022
When we first started planning for our DIY watermaker our two biggest concerns were price and space. There were only a few requirements: it needed to be electric and run off 12 volts, it needed to fit on our Alberg 30 in a pretty small locker, and it needed to be built for around $1000. Being energy efficient, quiet, and pump out a lot of water would all be great but size and price were the biggest factors. So we built a DIY watermaker that is small, and ended up costing less than $1300!
This watermaker runs at 900psi, produces around 3 gallons per hour, and draws around 14 amps. It may not be the most productive, but we are really pleased with the gallons per amps and just how simple it turned out!
Check out the video for full details on how we made this DIY watermaker!
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DIY Watermaker Parts
The prices listed in the video were from September 2021. Some prices may have increased since then but unless there are any drastic changes this should still be less than $1500 in total.
- Pumptec Pump-Pumptec does not sell to the public directly, and we found that the Sprayer Depot had the best prices. You do need to call/email them and ask for the cam with the .105 travel as they don’t have a listing for it on their website.
- Pulse Dampener
- Watermaker Membrane–Both the watermaker membrane and housing require an email or phone call to HCTI. They are very helpful! The membrane part number we used is MEM-2514SW-HF
- Watermaker Housing–Part number PV-2514SW-1000
- Needle Valve
- Pressure Gauge
- Primer Pump
- Pre-Filter Housing
- Pre-Filters
- 1/2″ Hose
- Brine Water Outlet Fitting
- NPT Fittings
Have questions and want one on one support, or looking for help in designing your own watermaker system? Consider becoming a patron where Andy makes himself available in a consultant capacity!
Dear sir,
Thank you for your details drawing, for the Needle Valve should be 1/4″ NPT? when i click on the given link for needle valve, it linked to
1/2″ needle valve. Can you clarify on this ?
Thank you
Gabriel
Hello! So sorry for the confusion! The needle valve should have been 1/4″, I must have slipped and clicked the wrong version when I made the link! Thank you so much for bringing it to our attention!
Greetings, We were just about to push the button on a $3500 water maker when we found you. Thank you for the article. Couple questions. Why only 1 pre filter? Most if not all WM use a 20 micron followed by a 5 micron. Second is that a brass fitting I see on the product outlet of the housing? I just spent 2 days replacing a rotted out brass fitting in our boat. Is there enough pressure on the product port to push the water say 25 feet to the water tank? Again thanks. fair winds, Jerry
I have the same question regarding the second filter
Thank you for sharing the details of your design. I am building a similar system with the same Pumptec pump. How did you determine your selected primer pump would be sufficient? This pump is rated for 160+GPH and 4.5m head (6.4psi) max. Pumptec suggests 20psi feed pressure and the total flow rate should be 9-12GPH. Do you have a low pressure side gauge? It seems like most primer pumps would be high volume, low pressure; so operation in your system would wear them out quickly or cause overheat. Why not use an automatic demand pump similar to the one that provides variable continuous pressure to your onboard plumbing? Example: https://www.sprayerdepot.com/products/slv10-aa40-automatic-demand-12v-pump-with-on-off-switch
Hi Andrew,
I talked to Pumptec about this when our original design just used a flooded inlet. 20PSI+ is ideal but in reality, any positive pressure on the pump inlet is acceptable. What you need to avoid is suction on the inlet side, which can cause cavitation within the pump.
The issue with a positive displacement on-demand pressure pump is it will be cycling on/off every few seconds maintaining its set pressure, I doubt the pressure switch will last long under those conditions. A centrifugal style pump can be “dead headed” without issue, with the downside that it only produces a few PSI.
Thank you for your response and advice. I think you are right about the demand switch wearing out. Is your pumptec pump above the waterline? Shawn at Pumptec advised me that if below the waterline; the pump should be OK without a feed pump.
My pumptec pump recently arrived and starting to acquire all the other parts you recommended. FYI to anyone that would like to utilize a pressure regulator; pumptec recommended this one for this pump in a watermaker application. It is very reasonable at $87 in stainless. https://www.specialtymfg.com/catalog/?page=product&cid=v555_ss&id=bpr_sst_555-6f-e_1000_psi_96
Hi,
Is this water maker still performing well? You had some trouble in the beginning that you fixed.. This Idea has compelled me to make my own system but not for a boating application.
The prices for the Pump, R.O. Filter and Vessel have gone up but not enough to detour me from making it myself.
The Pumptec part number I received from them is 81862. This part number includes the 0.105 travel. which can be purchased from Sprayer Depot
For the HTI products, (RO Filter and Vessel) can now be purchased thru their website: Hydrocomponents.us
Part # PV-2514-SW Vessel and MEM 2514-SW-HF
The cost for the pump, RO Vessel and Membrane is about 1150.00 Shipping not included.
Thanks for your efforts.
Regards,
Rich
Hi Rich! We have run into issues again but we believe it is all related to the original issue and the damage done to the pump at that time. We believe that if the original pump o-ring had not been damaged resulting in the seawater infiltration everything would be fine because all of the issues we have had have been related to corrosion from that incident. The bearing on the pump end of the motor seized due to its exposure to saltwater during the o-ring failure and that caused overheating which burned out the motor. We did get several hundred hours of use in before the motor failure (about 30 hours before the o-ring failure and about 200 after), and we believe that if that original saltwater infiltration had not happened it would still be functioning just fine. Given the same design requirements, we would still choose the same components. Hope that helps!
Does pulse dampening hose go between the pump and the membrane? That seems to make the most sense but I wasn’t sure.
Hi Gwen, I have a question concerning the membrane vessel.. is it really necessary to get a membrane vessal that can withstand 800 to 1000 PSI ?
What I understand is that the 60 bar pressure only builds up inside the SW RO membrane and the water that is pushed through is outside the membrane and flows out from the membrane vessel… therefore the pressure there must be very low right ?
So a much cheaper membrane vessel with 250 or 300 psi should do the job or not ?
Am I right that the salt water is pumped into the membrane and the fresh water accumulates on the outside of the membrane ? Or is it the other way round ?
This was my question about the maximum pressure that the membrane vessel should be able to withstand.
Hello Great video! I too am headed down the DIY watermaker route. do you know the pumptec model number for your pump? the link to the pump seems to be dead. Thank you for your contribution to the cruising world.
Hi,
I’m thinking to replicate your work and got two questions.
1) Which boost pump you use? I believe you replaced your original primer pump with some sort of pressure pump.
2) Where to use pressure dampening hose? Between pump and membrane?
Thank you very much for your help in advance.
Regards,
Masatomo Zaizen
Just wanted to drop this here as I build one:
Alternative for pressure regulator (not tested yet)
https://www.highpressurepumpsandparts.com/p-44567-general-100998-13-gpm-3-8in-x-1-2in-pressure-regulator-250-1000-psi.aspx
Just curious, what is the point of the cam with the .105 travel? How does that relate…maybe I should watch the video and find out…
Thanks
Jeff
Any updates on your water maker? Did rebuild the pump or buy a new one after the failure from your post in March 2023? After rebuild/replacement, how many extra hours/gallons of water did you get?
Not quite ready to pull the trigger on building one of these myself, but I wanted to check current costs (prices as of Jan 2024):
High Pressure pump (revised item): $816.32
https://www.sprayerdepot.com/products/pumptec-pumptec-107ss-105-m925-12v-pump-motor
Pulse Hose: $40.65
Membrane: $150
Housing: (need to contact for price, use your $300 figure for now)
Needle Valve: $35
Pressure gauge: $9.88
Primer pump (revised item – link above to a dead listing- I think this one has similar specs?): $33.79
https://www.amazon.com/TenNuoDa-Structure-Submersible-Brushless-Engineering/dp/B0BRB5GB5G
Pre-filter housing: $28.57
Pre-filter (2pack): $16.19
Hose: $27.99
Thru-hull (page linked above had smallest size 5/8″ – did you use 1/2″?): $5.49
Fittings (link above is dead, let’s say $100 for now)
That’s an estimate of $1563.88. I think pre-built watermakers have also gone up, so the savings are probably similar.
I’m also considering what it would take to motorize a Quenchsea watermaker. It’s a manual watermaker for $150, but only 1.6 Gal/hr, and some filtration is done in the membrane package, so it needs to be replaced every 6 months or 1000 liters – they cost $60 for 2.
Here is one good place to get the pump.
https://schoonerchandlery.com/shop/misc-2/schooner-chandlery-picks/pumptec-107ss-pump
Interested in knowing if you’ve figured out how to motorize the Seaquench. I’m a broke sailor who uses water also. Thank you. 😁
Like!! Great article post. Really thank you! Really Cool.
Thanks for sharing your experience with putting together a DIY watermaker with this Pumptec 107SS pump. Pretty cool. The company you link to for the Pumptec 107SS is no longer the best provider or the least expensive for this pump. We’ve learned from Pumptec that the official Pumptec dealer for DIY watermakers is Schooner Chandlery. They have the pump offered here on their website: https://schoonerchandlery.com/?s=pumptec&post_type=product and they seem to have a lot of different versions 12, 24, 36 VDC, and 3 different cams. They also have a bunch of the spares/parts that are needed. I helped a friend in Europe buy this pump from them and they ship worldwide and were very helpful to me with information about DIY watermakers. People can also contact Pumptec directly and be referred to a dealer but that referral seems like it will go to Schooner Chandlery. When you made your video it must have been different. Thank you again for sharing your experience here with a video.
Great article! have started assembling a system for my boat.
Is there a reason you keep switching hose/tubing sizes?
The parts list includes 1/2″ tubing, but the pre-filter housing is 3/8″ and everything after that (high pressure pump, needle valve, pulse dampener) are 1/4″