Marine Water Makers Q & A

For every email we get asking a water maker question, there are more out there thinking it.  So here are some of the common questions we are asked about our high output water makers.

I have read in the Owner's Manual that the high pressure pump motor gets hot to the touch when running and the membranes don't like to be mounted in a hot location. My preferred mounting location would put the motor and membranes in the same locker, which is about 12"H x 16" W x 60" L. Would this create an issue with regards to over heating my motor or membranes? Should I add ventilation to the locker?

Just to give you an idea of heat, I have the RO Membrane assembly on THIRD DAY mounted in my engine compartment.  When I take temperature readings with my infrared heat gun of the RO Membrane surface (I love that heat gun by the way for $20 from Harbor Freight) I've never seen my membrane housing temperature above the temperature limits.  So it would be hard for me to believe that the heat from the electric motor could elevate and heat soak your locker space more than my 120Hp Ford Lehman during a 24hr run in the Sea of Cortez.  It has been a long time since my collage physics class, but the heat generated by the electric motor should be able to be dispersed and not over-temp your RO Membranes.  However, we had a client who mounted his pump and motor assembly in a locker below his quarter berth with no ventilation.  The locker size was 23"W x 11"H x 100" deep (25,300 cubic inches).  He found that after 1.5hrs of running his unit the thermal overload on his 1.0Hp motor would trip and shut down.  He was able to solve the problem of inadequate air ventilation by making some holes in the locker and installing a small 12v computer fan to pull cool fresh air into the locker space.  For reference, the boost pump motor casing temp runs about 130F, the high pressure pump runs 165F, and the 1.0Hp electric motor runs 165-190F, depending on where on the motor you take your reading.

How far away from each other can the modules be mounted?

The individual modules can be mounted as far apart or as close together on your boat as space dictates (I’m assuming you don’t have a 300ft Mega Yacht and want to spread the Modules from stern to bow).  But a distance of plumbing of 10ft between the modules will not have a negative effect on system performance.  The sea water boost pump is over sized in delivering sea water to the high pressure pump and making sure your high pressure pump gets plenty of flow.  The SeaMaker water makers come standard with 30ft of sea water inlet connection tubing, 30ft of brine discharge tubing and 30ft of fresh drinking water tubing, and a 3ft and 5ft high pressure lines to connect high pressure pump to the RO membrane pressure vessel assembly and to the remote panel.  Although these amounts should cover most installations, additional lengths of tubing can be supplied.

I'm comparing your water maker to one of your competitors. Their replacement RO Membranes cost $399 to $699 and your Membrane only costs $187. When I asked them why, they say that their membranes are more heavy duty and have a higher salt rejection rate than the ones you are using. They also said that your RO Membranes were made in china which is why they were so cheap and would not last as long as their higher quality membranes. Can you tell me more about your RO Membranes and tell me why you are able to sell your RO Membranes for so much less than your competition?

Honestly, we have been asking ourselves the same question, why do the other guys charge so much for their membranes when a Dow Filmtec SW30 series membrane is the industry gold standard in terms of salt rejection and membrane life?  Here is a link to the technical specs for the SW30-2540 Dow Filmtec RO Membranes that we use in our water makers.  My recommendation would be to ask the competition to send you the technical specs for their RO Membranes and compare for yourself.

The truth is, I think the simple answer for why the other guys charge so much is because they have been getting away with it for years!  It's part of why the marine industry loves the proprietary parts game or why they don't want to tell you the manufacturer of parts they are using in their system.  Some water maker companies even custom build their own RO Pressure Vessels slightly smaller than the industry standard 40 inches, so they can lock you into buying only their brand of RO Membrane, at a crazy high price of course.  When asked why their membranes are so expensive, they can't just say because they have a huge profit in them and are hosing you, so they say because their Membranes are  "special".  Well they are special all right, specially designed to drain your cruising kitty.

Being a cruiser out here in the anchorages, I'm simply not interested in soaking clients with high priced consumable parts once they have put their trust in me and installed one of my water makers aboard their boat.  This is a business of course, and we do make a few bucks when we sell a RO Membrane for $187, just not anywhere near what some of the other water maker companies are making, and I'm fine with that.  I want happy calls over the VHF radio from cruisers telling me how happy they are with their water maker and inviting me over for a beer or taco!

Are there any water level, height, or heel angle restrictions for the installation?

The only restrictions would be that the motor/pump assembly needs to be mounted in a location so that it will NOT get splashed with water, for obvious 120v electrical reasons, and that the crank shaft vent is pointing towards the sky.  The only heel angle restriction is that the placement of your watermaker through hull needs to be low enough where it doesn’t come out of the water while operating the unit while underway.  Over sizing of the sea water boost pump and making is self-priming pump takes away the standard concerns or requirements on where you mount your water maker system components.  Below or above the waterline installations are both perfectly fine.

Does the water maker require a dedicated through hull for sea water input?

No - BUT, by not having it’s own dedicated through hull, you could be asking for trouble.
Here’s a quick list of the potential risks in attempting to share a through hull and it’s our recommendation that your water maker does have a dedicated sea water inlet through hull.

1. The high pressure pump and RO membranes do not like air bubbles (possible damage).  When the system is operating there will be a vacuum at the through hull and any T-fitting, so that without the proper hard shut off valve, first water and then air could be sucked into the water maker intake lines from the other system attached to the through hull.

2. There is the “risk” of insufficient flow to the inlet of the water maker if two systems are pulling from the same through hull.

3. The other system now sharing the water maker through hull may be starved for flow or suck back air through the water maker plumbing. If T-ed into the engine’s raw water cooling system, for example, this would be bad with obvious problems in overheating the ships main engine.

All of these concerns can be addressed by a proper plumbing installation and with a few extra on/off ball valves, but it will also then add extra complexity to the operation of your water maker, with extra valves to access and select at start-up and shut down. Some people are ok with this as a trade-off for the extra cost in putting an extra “hole” in the bottom of their boat, but Cruise RO Water’s cruising and design ethos is simplicity, so we would strongly recommend a dedicated through hull for your water maker.  

What about waste water?

The waste water, or technically brine in RO speak, can be discharged from the boat in a way that you feel the most comfortable with.  A simple above the waterline plastic through hull fitting for discharge overboard is the simplest solution. 

How frequently can it/should it be run?

SeaMaker water makers are built using commercial grade parts to commercial standards of construction and can be run every day or as little as a few days per year.   Your water needs will determine the actual run time.  RO systems, like many pieces of equipment, like to be run, but if stored properly can offer intermittent use without damaging the system, particularly, the RO Membranes. 

Let’s look at the most efficient way to operate your water maker.  At the end of each run, there is a fresh water flush of the water maker to inhibit biological growth.  This takes about 2-3 gallons of fresh water (depending on the length of lines in your system).  So if you run your water maker every day for 1 hour and make 20 gals, you could then use 3 gallons to flush your system, giving you a net water production of 17 gallons per day.  Now let’s say you run for two hours every other day.  You will still use the same quantity of fresh water to flush the system (3 gals) but now you have a net water production of 37 gallon (or for comparison 18.5 gallons per day).  So you can see the small, but measurable, difference in the efficiency of a longer run time every other day compared to a daily run.

Another factor in determining the most efficient run time is that if the system sits unused for more than 3-5 days, you need to do one of three things:

1. Flush through another 2-3 gallons of fresh water.  You can continue this 3-5 day fresh water purge indefinitely rather than adding preservative. 

2. Add some preservative to the system for longer term storage, know as pickling.

3. Run the water maker

This issue of fresh water flushing and adding preservative isn’t something special or unique to our systems, but is simply a factor RO membrane maintenance.

What about membrane preservation and pickling? How often, how time consuming?

If you are not letting the water maker sit unused for more than 5 days, then you should never need to add a preservative to your system, which is known as pickling.  However, if you will not be using the water maker for more than 5 days, the preservative can be introduced to the system by mixing the pickling solution in a 5 gallon bucket and then sucking the solution through the system, utilizing the supplied three-way pickling valve.    The entire pickling process should take no more than 5 minutes and despite what I like to call "dock expert and cruiser rumors" pickling does NOT hurt your RO Membranes.  The Sodium Metabisulfite pickling reagent we use is the exact same preservative that Dow Chemical puts in their RO Membranes when they manufacture and ship them out! 

How easy is it to operate a water maker?

Here’s a brief look at the basic start-up, operation, and shut down procedure, which is all detailed in the operation and maintenance manual.  I’ll do this in bullet point format, but I think it will give you a pretty good idea of the simplicity.

1. Turn on the sea water boost pump and let run for 1 minute to push fresh sea water into the system and purge out any old water and preservative along with air bubbles.
2. Turn on the high pressure pump and let run for 1 min
3. Slowly turn the pressure regulating valve clockwise until the pressure gauge reads 800PSI
4. Sample the fresh water using the TDS meter
5. Turn the product water selector valve to send the product water to the water tank

1. Periodically monitor the system PSI and product water output for the desired run time

Shut down:
1. Turn the product water selector valve back to sample (away from tank)
2. Slowly turn the pressure regulating valve counterclockwise to lower pressure from the system as indicated on the pressure gauge
3. Turn off the high pressure pump
4. Turn the feed water select valve to pull fresh water from tank (or bucket if desired) to begin system fresh water flush
5. Turn the high pressure pump back on but DO NOT turn the pressure regulating valve to put the system under pressure.  Run the system like this for the required length of time so that fresh water is exiting the brine (once you measure this time, you will know how long based on your systems plumbing length)
6. Turn off high pressure pump
7. Turn off boost pump

What about water testing, how do I know the water is safe to drink?

All SeaMaker water makers come with a hand-held TDS meter so that you can periodically test the TDS (Total Dissolved Solids) of the product water.  Once you are familiar with the operation of your system and how long it takes for the product water TDS to be acceptable for drinking, testing the TDS isn’t something you need to do every time, but simply test periodically as a way to monitor system performance.