Energy Recovery Watermakers — Running a Watermaker on Solar and Batteries
- Adam Morris
- Nov 19, 2025
- 10 min read
Updated: 23 hours ago
After going no-generator, all lithium a few years back, all new equipment that goes on Connie has to fit into our (mostly solar-generated) power budget. And it was long past time to re-add watermaking to Connie's list of skills.
There's a big allure to the Energy Recovery—or "ER"—watermakers, namely the promise to use a fraction of the power per gallon/liter. "Save 75-80% energy per liter/gallon!" is prominently featured on every ER manufacturer's marketing materials. Sounds like some real world testing on Connie is in order!
Long story short, we decided to test out a Schenker Smart 60, and found that the claims can be true, but strangely not under the advertised circumstances.
Was it worth it? For Connie's generator-less setup, yes, I believe so. For those not looking to ditch the generator? Very questionable. There's the premium cost, added complexity, and, depending on the manufacturer, various additional points of failure.
Today let's dig into the truth to those 75-80% power reduction claims, review some comparisons, and discuss who I think an energy recovery watermaker (and it's hefty budget) makes sense for.
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Energy Recovery vs Conventional Comparison
Instead of wasting the pressure in the salty reject stream (brine), an energy-recovery device (ERD) captures that pressure and uses it to help pressurize the next slug of seawater going into the membrane—which means your electrical pump doesn’t have to do all the work.
A conventional watermaker uses a beefy high-pressure pump to push all the incoming seawater through the membrane. The brine leaves the membrane still at very high pressure and is then thrown away across a valve—along with that sweet sweet energy. In an ER system, the brine’s pressure is handed back to the incoming seawater through a pressure-exchange or intensifier mechanism.
In the past, there were very few energy recovery options—Spectra being the original followed by Schenker out of Italy. Now we have options from the likes of ElectroMaax, Osmosea, Aqua-Base, Parker, Eco-sistems, and Blue Gold.
Depending on where you live, availability of these newer brands may be scarce, however. Parts and support may be even scarcer.
Comparison Table of Energy Recovery vs Conventional Watermakers
There are many watermaker manufacturers targeting the recreational marine industry, but let's focus on common ones that I've actually seen installed on boats in the wild (and not just in booths at boat shows).
We'll compare a couple of energy recovery (ER) watermakers with a few conventional units. Note that there are watermakers with rated outputs all across the range for both ER and conventional. However, as we'll discuss, most conventional watermakers that people own are going to have a much higher total rated output than an ER, as you'll see in my examples below.
Pay special attention to the "W/L" or Watts per Liter in the table below:
A few notes on this table:
Prices are from United States distributors as publicly available at the time of writing and may vary drastically by country.
There are a number of conventional AC watermakers that I have personally seen at boat shows that are in the $10,000-15,000 range for the same 40gph output. I have not included these, as I have never seen one in the wild.
Price comparison gets very muddy when you start adding options, especially automatic features. The Rainman, for instance, goes from $5,000 to $10,000 in a hurry.
We can see that based on just the advertised specs, the gains in W/L are impressive, but 75-80% power reduction seems like some pure marketing nonsense.
When we put it to the test, though, our Schenker ER unit can actually live up to the marketing claims, albeit when it's set to half capacity.
Our One-Year Test of the Schenker Smart 60—Sipping Power
The headline efficiency of 75% energy savings vs traditional did show up for us, but only running it on single-pump mode. The Schenker Smart 60 actually has two pumps, allowing you to run only one at a time to run at half power usage. Pretty neat, actually.
With one pump, the Smart 60 was producing 40-42 liters per hour (10.5-11GPH) at only 110W. That's a seriously impressive 2.75 W/L. However, in dual pump mode, the watermaker hits (or slightly beats) the advertised 60 L/h at ~240 W, but efficiency falls back toward ~4 W/L.
The power usage for one pump is so low that it barely requires any consideration in our power budget. If we're starting the watermaker as we leave the boat, the solar more than keeps up, and we usually come back to fresh water and full batteries.
Is there a catch to running it with one pump? Possibly.
In my discussion with the CEO of SLCE Aqua-Base watermakers, Benjamin Gury, he questions the viability of such a solution:
"The idea of using the Schenker unit with only one pump instead of the 2 has the advantage of reducing the power consumption. However, the quality of the water produced will be greatly reduced. It would be the same with any watermaker as the size/number of membranes are related to the seawater flow and the production flow needed. If you have some margin around the nominal point, 50% flow variation is too much in my point of view."
Schenker advertises the use of a single pump as a sanctioned power saving feature in their documentation. So, it looks like we have some additional testing to do and will update this section.
Quick note: almost all of our testing was done in ideal watermaking conditions thus far—clear, warm Caribbean waters. The conditions can have a significant impact on water production, so we'll have to provide updates as we do further testing.
To Generator or Not to Generator
As I mentioned earlier, most of the conventional watermakers that I see in the wild are going to have a much higher rated output than energy recovery. That's because folks are going to want to optimize for different things. If you're using a conventional watermaker, the goal is to produce water as quickly as possible to minimize generator runtime. The energy reduction is much less important since you're producing so much power anyway.
Cruisers tend to run all of their high load appliances at the same time while the generator is running, so energy reduction can have an impact if you're already reaching limits in your generator output. But, most folks can comfortably run a watermaker, an air conditioner or two, and the water heater, as well as still get some battery charging in there.
However, if you're one of the many that is on the mission to get rid of the generator entirely or only run it sparingly, this equation changes completely.
So, Who is an Energy Recovery Watermaker for?
The Case that a Generator is Becoming Irrelevant.
If you're at the stage that your generator is ready to be retired or you've outgrown your current generator—or maybe you just don't want to hear an engine ruining your most peaceful anchor moments—you've already got significant investments to make.
Today's marine generator can easily start at $15,000 before even discussing the installation. In our case, to even remove the old generator, we had to dismantle part of a stateroom ceiling, hire a crane, pull the propulsion engine, and then have a crew help us get the generator out. That's a lot of budget that can be put into other systems. And, on a catamaran, that's some decent weight savings.
I have discussed this at length in other articles, but, just as a refresher, today's marine tech gives us high output alternators, smart regulators, and many more solar options than before—plus cheap lithium battery options to store all of that energy. If you're looking to squeeze in more solar, I also suggest my article on the new CIGS panel consturction and its advantages.
The upsides, of course, are not having a whole entire extra engine to maintain and your peace and quiet at anchor. However, the tradeoff is that we're on a much more strict power budget, and power efficient marine systems are more expensive and often more complicated.
Does More Complexity Mean More Maintenance and More Failures?
The process that ER systems employ means that there’s a bunch of new parts that are going to be taking abuse. When I listen to the signature “heartbeat” from an ER watermaker, I hear a combination of innovation and components taking abuse.
The ElextroMaax Solution
Let's look at ElectroMaax's take on this problem. Their goals are to make wear parts more serviceable, and upgrade various parts to titanium for a longer service life.
The video below, while a bit dry, is a great explanation of what ElextroMaax focused on tweaking, It's also a good explanation of additional maintenance to be expected and what failure points look like.
This Clark Pump based design, for instance, still requires piston maintenance, seals to be changed, and various other wear parts that need to be monitored. And incorrect maintenance or operation can cause catastrophic failures.
The Schenker 2.0 and Discussion with Schenker's Founder
As for Schenker, a number of years ago, they released a version 2.0 of their ERS. Riccardo Verde, Founder & CEO of Schenker, was kind enough to walk me through it:
"It's worth noting that Schenker introduced version 2.0 a few years ago, eliminating all internal seals and O-rings. The sealing elements were replaced with innovative composite pads, which offer even greater wear resistance than steel. The result is that the current Schenker ERS is a virtually maintenance-free component, successfully tested for years of continuous use. Of course, the only condition is that the water be properly filtered (using appropriate pre-filters, replaced regularly), preventing sand, coral, or sediment from entering the system.
I don't entirely agree that all energy recovery (ER) watermakers tend to be less reliable than traditional watermakers. It's certainly true that ER watermakers include an additional component, the ERS, which potentially introduces a failure risk.
[...]ER watermakers, on the other hand, don't make use of high-pressure pump of traditional watermakers, which is a critical component and a frequent source of failure. In fact, high-pressure pumps, which push water through the membrane with brutal force, are generally three-plunger metal pumps, designed for very different applications, typically car washes.
Using these pumps with a highly aggressive fluid like seawater makes the application quite critical, and failures of high-pressure pumps in traditional systems are quite common." -Riccardo Verde, Founder, Schenker Watermakers
In a separate conversation with Benjamin Gury, CEO of SLCE (Aqua-Base Watermakers), he also added the following:
"In terms of lifespan, our ERD runs at low speed (one switch every 6 seconds on a 65 L/h system), which allows us to reach a very long life span on the seals. Considering the low running hours on most sailing boats, it would be decades."
We have come a long way into making ER more reliable for cruising. There is still the issue of using specialized equipment versus widely available parts. Though, any world travelers would undoubtedly want to keep spares of main components, like pumps, for serious off the grid adventures, regardless of the type of watermaker.
Automation Features Add Even More Complexity
For our install, I added Schenker’s touch panel and all the optional sensors that go with it—automatic salinity divert, flow, and pressure. That's roughly $2,000 worth of add-ons .
This makes the unit very set-it-and-forget-it. If we're producing less water per hour than a conventional, we're running the unit for longer and more often. But, a goal of this whole generator-less setup is more nature sounds, less mechanical noise.
In actual usage, we wanted to be able to just hit a button on our way off the boat to our next adventure mission, and arrive back stocked up with freshly made water.
With the added salinity sensor and diverter relay, the unit knows when the water salinity level is safe, and automatically diverts it to the tank, without any user input. With an extra button push at startup, the unit also auto-flushes itself with fresh water after the run—extremely important if you don't want to severely reduce the lifespan of your expensive components.
This is all managed from the remote panel, which is very helpful for anyone whose watermaker is tucked away in an engine compartment or any hard-to-get-to space.
All this culminates into a great experience so far running the watermaker. We hit two buttons before hopping off the boat and come back to fresh water. If cruising is about spending a lot of money to make everything in life harder, these conveniences won't aid in that quest.
Schenker-specific Install Learnings
These may all be specific to the Schenker install, but I suspect similar issues to exist across the industry. Watermaker companies are generally small manufacturers. If you're expecting a Victron level of polished documentation, Schenker's manuals and labeling is going to be quite lacking.
The documentation in my box didn’t include the optional wiring diagrams for the touch panel, flow sensor, and pressure transducer. They exist; they just weren’t there.
The English translation in the manual is serviceable but occasionally asks for a second pass. Coupled with the organization, you might end up doing something like ordering 3/4" hose after seeing the spec for 3/4" thru-hulls, when pages later you'll see that a 5/8" hose is actually the spec.
Also, the feed pumps are more sensitive to getting enough water flow than the manual will lead you to believe. My seawater inlet is within the specified distance from the pump group. However, in full power (both pumps) mode, I still had cavitation problems from the pump's not getting enough water.
I figured that my run was a bit too complicated, and that was confirmed by Rich from Cruise RO Water and Power, a US importer for Schenker Watermakers. Ninety degree bends are an issue for the run.
I also wish that the Schenker came with NMEA 2000 integration. There is an expensive optional box that can be added for MFD integration, however, I see no reason why N2k can't be built directly into the remote panel and then easily connected to the N2k network. This would allow me to get all of the data into SignalK and provide easy remote monitoring when we're away from the boat.
NMEA licensing costs play a role here, understandably. SLCE (Aqua-Base Watermakers), had this to say about excluding NMEA for their own watermakers:
"NMEA2000 is very expansive to get and to keep. It is not a technical issue. It is a fee issue to the NMEA organization."
-Benjamin Gury, CEO, SLCE Watermakers
Wrapping Up
The innovation focused on reliablilty and maintenance has broadened the range of who should consider an ER watermaker. Given the added complexity and increased cost, I still think that they make the most sense if you're on a generator-less or generator-minimizing mission like we are. In fact, it's kind of a must-have if you're heading into this journey.
I do think that the automation features (on any watermaker) change the way we handle watermaking. It's squarely in the quality-of-life improvement category, albeit at a hefty price tag.
If you've got questions or have an energy recovery watermaker nightmare to share, drop a line in the comments to help folks who are also making this investment!
