Features January 1, 1998 Issue

Test of Six 12-volt Watermakers

While at first blush all appear about the same size, we find important differences in output and current consumption. The Spectra 180 is amazingly efficient but expensive. Of the six, Village Marine Tec's Little Wonder seems the most tried and true.

Last month we took an overview of the pros and cons of 12-volt watermakers. This month, we look at high-output machines from five manufacturers, ranging from systems from industry giants such as Village Marine to small shops such as SK Engineering. All of the watermakers we looked at were production models, although the Spectra 180 we tested had been re-configured to serve as a demonstration model.

As we began our market survey and field testing, we discovered that a number of other manufacturers are jumping into the fray, realizing that 12-volt watermakers constitute a small but growing segment of the market. Most notable among these new players is HRO—another industry giant—which has been promising a state-of-the-art, computer-controlled, self-contained 12-volt watermaker for more than a year. We saw the literature a year ago at the Miami Boat Show. We saw a non-operational mockup last fall at the Southampton, England boat show. We have yet to see a functional machine in the flesh.

With the assistance of Andy Cortvriend of Ocean Link, a knowledgable Portsmouth, Rhode Island, marine servicing company, we tested product output, water quality, and electrical consumption of all the watermakers. Electrical consumption was measured with a Cruising Equipment amp-hour meter, using gel cell batteries maintained at full capacity by a Heart inverter/charger between tests.

Saltwater was pulled from lower Narragansett Bay into a large storage tank maintained at a constant temperature during the tests. The waters at our Little Harbor test facility are not as clean as open ocean waters, but are closer to the reality of the watermaking most cruisers will experience. This was not a pure laboratory test with manufactured sea water of exactly the right total dissolved solids (TDS).

We then examined each machine carefully on the bench, looking for weak points, strong points, potential installation or maintenance hang-ups, and general quality of construction.

The quality of output water was tested with a TDS meter and all machines easily met standards for potability.

The real test of any watermaker is how it performs over time—not just months, but years. Because maintenance is a key factor in longevity and trouble-free operation, the owner/operator will bear a large portion of the responsibility for the long-term success of any watermaker installation.

Here are our findings.

Village Marine Little Wonder
When Village Marine Tec’s Little Wonder was introduced almost a decade ago, it was the first 12-volt watermaker that actually had the capacity to supply the water needs of a medium-sized cruising sailboat without almost continual running. More than 1,500 of these compact, well-made machines have been produced, and there have been virtually no changes to the design or components over the entire production run.

Both 12-volt and 24-volt models are available, with the higher voltage model producing slightly more product flow.

The standard model is totally self-contained in a well-designed package, with all components bolted to a heavy aluminum chassis, topped off with a removable aluminum cover. Mounting requires drilling through the chassis for suitable through-bolts.

The three plumbing connections—feed water, product water, and brine discharge—are pre-plumbed through one end of the case. The wiring junction box also contains connections for an optional feed water boost pump, and an internal 25-amp breaker to protect the electrics.

Although the package is tightly plumbed, there is reasonable space between components for service.

Power for the high-pressure pump is provided by a continuous-duty 1/4-hp. Pacific Scientific motor, rated at 21.5 amps at full power. The motor is connected to the high-pressure pump by a lightweight cogged belt.

The heart of the Little Wonder is its proprietary high-pressure pump, specially made by Village Marine for this machine. It features a titanium pump head with ceramic plunger—a combination which should be corrosion-proof for the life of the watermaker. All wetted parts in the pump are titanium, type 316 stainless steel, or ceramic. High-pressure plumbing and connectors are type 316 stainless.

Monitoring includes a high-pressure gauge and product flow gauge. System pressure can be adjusted if necessary using an open-end wrench, although the factory pre-set pressure of 800 psi should be correct for most watermaking situations. The pressure regulator is a high-quality regulator, rather than the more commonly seen needle-valve adjuster.

The fiberglass pressure vessel and the standard-sized 2521 membrane are both manufactured by Village Marine, although they are industry-standard in size.

In our tests, the Little Wonder produced a product flow of 5.8 gph at 13 volts, drawing 16.7 amps—about 37.4 watts per gallon. This does not include the 1-amp current draw of the small optional booster pump, which is required for above-the-waterline installations, long feed water runs, or installations containing multiple pre-filters.

The water produced by the machine we tested was very high quality. The noise level of 79 dB, with the cover removed, was louder than the two quietest machines tested, but was not loud enough to be objectionable.

The self-contained unit is 25.5" long, 11" wide, and 9.25" high, and requires a slightly larger mounting space to accommodate plumbing connections and allow access for removal of fastenings holding the cover. For tight installations, a modular version is available, which does away with the mounting chassis and uses flexible high-pressure hoses rather than rigid stainless steel tubing. Obviously, installation of the modular unit requires slightly more time, but offers a lot of flexibility—very desirable in field installations aboard the typical cruising sailboat, in which locker or shelf space is at a premium.

Documentation is excellent, with a 35-page manual covering installation, operation and maintenance.

The warranty is somewhat complex. The membrane has a three year warranty, the pressure vessel a lifetime warranty, the high pressure pump a one-year warranty—although some of its internal components have only a 90-day warranty—and the electric motor 12 months. You need a flow chart to keep it straight.

The Little Wonder comes with pre-filter, three-way cleaning valve, basic plumbing connectors, and a membrane cleaning kit. You supply PVC hose, hose clamps, and the wiring connection. Options include the boost pump (standard with the modular version, $144 for the self-contained version), a three-way sampling valve ($38), a pre-plumbed fresh water flushing system ($150), hand-held salinity meter ($49), and spares kit for extended cruising ($199). For long-range cruising, all of these options are nearly essential for any properly installed watermaker.

List price of either the self-contained or modular 12-volt Little Wonder is $3,195. It is available at slight discounts through some mail-order catalogs, and there are periodic promotions at boat shows featuring special prices and thrown-in options.

Weight of the self-contained system is 63 lb. (The modular system weighs 48 lb.)

Village Marine will soon introduce a higher-output version of the Little Wonder, a 1/3-hp. watermaker in almost the same package size. Current draw, however, will be about 26 amps, requiring heavier wiring and perhaps a look at your battery capacity and charging capabilities.

Bottom Line: There are quieter 12-volt machines, more efficient ones, cheaper ones, and others that put out more water. The Little Wonder, however, has a combination of features—ease of installation, relatively low current draw, high quality components, and a 10-year track record—that is hard to beat. You can’t go wrong with this watermaker.

SK Engineering DC 150
SK Engineering is a small watermaker manufacturer based in Ft. Pierce, Florida. They do virtually no advertising, go to few boat shows, and have a very low-overhead operation geared to the Florida market. While most of their units are AC-powered, their DC 150 is a 12-volt model with a nominal output of 6 gallons per hour.

The DC 150 is powered by a 1/3-hp. continuous-duty Pacific Scientific motor rated at 26 amps. This is a larger version of the motor that powers the Village Marine Little Wonder.

The membrane is a standard 2521, and the pressure vessel appears identical to that used by Village Marine. All high-pressure fittings are type 316 stainless, as is the rigid high-pressure plumbing.

A Giant high-pressure pump provides pressure for the system. This is a standard industrial pump with a stainless steel pump head. A complete servicing manual for the pump is provided.

This is an open-frame system, with the components mounted on a heavy aluminum chassis. The footprint is 18.5" x 12.5", with a height of 8.5". The pressure vessel is mounted on the outside of the chassis, increasing overall dimensions to about 25" long outside the footprint of the mounting frame. Rubber vibration mounts are provided to isolate the chassis, reducing noise and vibration.

System pressure is user controllable via a knob-operated valve on the panel. Monitoring capabilities include system pressure and product water flow.

In operation, the DC 150 was one of the quietest machines tested, producing a maximum of 72 dB of noise. Product flow of the test machine was 6.5 gallons at 800 psi, with the motor drawing 21.3 amps at 13 volts. This translates into electrical consumption of 42.6 watts per gallon of water produced. As with other systems, adding a booster pump for above-waterline installations would add to total current draw. SK states that the system will operate without a booster pump in installations up to 2' above the waterline.

One of the nicer features of this machine is the availability of a remote operating panel. This option allows routine operation of the system without direct access to the watermaker itself, which greatly increases installation flexibility.

The system is supplied with a pre-filter with a vacuum gauge, allowing you to monitor the condition of the filter without opening the housing. A freshwater flush kit—highly-desirable in any installation—is a $125 option. The 12-volt booster pump, drawing 1 amp, is a $120 option. An extensive cruising kit, including 12 pre-filters, rebuild parts for the high-pressure pump, cleaner, preservative, and other spares, costs $330.

SK’s pricing is very competitive. The self-contained DC 150 has a list price of $2,740, but has a discount price—which we suspect would be available to most sailors who approach the manufacturer directly—of $2,350. The remote panel version has a discount price of $2,450, although the list price jumps to $3,140.

The system documentation is basic, but adequate. Total system weight is 74 lbs.

Being a small manufacturer, SK has a limited network of regular servicing dealers, but since all the system components are essentially off-the-shelf items, any good watermaker technician could repair the unit if necessary.

This is a quiet system with high-quality components and a great deal of installation flexibility when coupled with the optional 8" x 8" remote panel. Its open-frame design is easily serviced, although the package is not as neat as a totally enclosed package like the Little Wonder.

Bottom Line: With its 1/3-hp. motor, electrical installation will require careful thought, and you will need to look at your entire charging system and battery capacity a little more closely than you would with a 1/4-hp. machine.

The low price makes this system worth looking at. It is simple, soundly engineered, and utilizes good quality, standard components that are easily serviced. The only potential drawback is the small size of the manufacturer, which might limit long-term support.

PUR PowerSurvivor 160E
The PowerSurvivor 160E is PUR’s entry into the high-output 12-volt watermaker market. It is the latest in a long line of machines that dates back to the PowerSurvivor 35, the first practical small 12-volt watermaking system.

The 160E uses a standard 2521 membrane in a proprietary housing. It is a dead-simple modular system, utilizing a Leeson 1/3-hp. motor directly coupled to a proprietary stainless steel high-pressure pump. Flexible high-pressure hose between the pump and the pressure vessel allows a great deal of mounting versatility, including bolting the entire system to a bulkhead. All high-pressure fittings are 316 stainless steel.

At 54 lbs. for the entire system, this is one of the lightest high-output watermakers we tested.

When we say dead-simple, we mean it. Other than the pressure bypass valve and the on-off switch—which you provide—there are no gauges to monitor, no product flow meter, and no means of adjusting system pressure, which is pre-set at the factory and is not intended to be user-adjusted. You would still, of course, install the product sampling valve, cleaning valve, and pre-filter, just as with all other units.

The 160E is a gravity feed system, and can only be installed below the waterline.

Our test machine produced 6.5 gallons of water per hour, drawing 17.3 amps at 13 volts—less than we would expect for a 1/3-hp. system. This yields an energy consumption of 34.6 watts per gallon of water—more efficient than average for the watermakers in our tests.

There are several drawbacks to the PowerSurvivor 160E. First, the system is the noisiest of any we tested, putting out 80 dB at our standard test distance of 1'. Furthermore, the reciprocating drive system of the high-pressure pump produces not a steady noise, but one punctuated by a loud popping sound at one stage of the piston stroke. We would recommend mounting this watermaker in a sound-insulated compartment if possible.

The reciprocating pump also produces pulsing in the system’s hoses, which should be well-secured to prevent fatigue over time.

This is one of the more expensive watermakers we tested, with a list price of $4,440. Several discount marine catalogs sell the 160E for as low as $3,800. Options include a repair seal kit ($80), an extended cruise kit ($200), and an extensive preventative maintenance package ($420).

On the plus side, routine service of the system, including replacement of high-pressure pump seals—a requirement every 1,000 hours of operation—is simple and well-documented in the excellent instruction manual.

We also looked at two other units from PUR, the PowerSurvivor 80II modular and the newly-designed PowerSurvivor 40E. The 80II is very similar to the 160E, simply scaled down. We did not test it, but since all the other PUR machines met the manufacturer’s specifications, we expect this one to do the same. The smaller-diameter membrane of the 80II limits you to membranes from the machine’s manufacturer. It lists for $3,330, and is routinely discounted to about $2,950—about the same as the higher-output Little Wonder.

The PowerSurvivor 40E is the totally re-designed successor to the PowerSurvivor 35, the original “high-output” 12-volt watermaker. In our tests, its 1/18-hp. motor drew 4.8 amps, producing about 1.6 gallons per hour, consuming 39 watts per gallon of water. It is very compact, and like all PUR watermakers, easy to service and operate.

At 72 dB, its noise level was the equivalent of the quieter large 12-volt machines.

With its light weight (25 lbs.) and tiny footprint—about 15-1/2" x 15" x 6" high—the 40E would be the most suitable watermaker for a single sailor or a couple cruising on a small or very light boat—a multihull, for example—with limited electrical generating capacities, perhaps just a few solar panels and small batteries.

In an emergency, the motor can be disconnected from the 40E, and it can be operated manually by a handle, just like its Survivor 35 predecessor. Because virtually all the parts of the 40E are proprietary, including the pressure vessel, membrane, and pump, you will only be able to service the units with parts from PUR.

List price of the 40E is $2,220/$1,900 discount, with options analogous to those available for larger PUR machines.

Bottom Line: All three of these smaller watermakers are actually the core business for PUR, and fill specific niches where there is no competition. Although the 160e is an easily serviced watermaker, and is more efficient than average, its high price and noisy operation are drawbacks. If the installation flexibility of the 160E is not essential to you, we think there are other 12-volt watermakers of similar capacity and quality of construction that offer better value.

Caribbean Technology
The Caribbean Technology YM-200 DC 12 made by Great Water is the highest-capacity 12-volt watermaker we tested. Its rated output of 10.2 gph at 800 psi significantly exceeds that of most of the watermakers in our test.

In many ways, this modular system mimics both the output and sophistication levels of more mainstream engine-driven or 110-volt systems, including a direct drive high-pressure pump, high and low pressure automatic shutoff, and a sophisticated remote operating panel including power switch, pressure regulator, and gauges for system pressure, product water flow, and brine flow.

Power is provided by a 1/2-hp. continuous-duty motor directly coupled to a stainless steel Wanner Hydracell industrial pump. An instruction manual for the pump leads you through the periodic maintenance required. A new oil venting system in the pump claims to have eliminated an earlier tendency of Wanner pumps to weep oil.

A Codeline pressure vessel holds a standard 2521 membrane. Because this is a modular system, high-pressure plumbing includes flexible hose rather than rigid tubing. All fittings are 316 stainless steel.

A Flojet boost pump is standard, allowing the system to be mounted above the waterline. This pump—actually designed as a shower drain pump—adds 3.6 amps to the current draw of the system.

A product flow rate of 10.2 gph is pretty much the absolute capacity of a 2521 membrane, and our test system had no trouble achieving that rate of flow. The downside is that to achieve this flow, the electrical demands of the system are much higher than any other watermaker we tested: 38 amps at 13 volts, or 48.4 watts per gallon.

You would never run this system without running the engine at the same time. The current draw is high enough to drop system voltage down instantly. In all fairness, for maximum efficiency none of the systems drawing 15 amps or more should be operated without running the engine at the same time.

Because of the high current draw, your charging system should be equipped with a big alternator if you choose this watermaker. To take advantage of the big alternator’s capacity, you’ll want a big bank of batteries. The system will probably need a 50-amp circuit breaker separate from the main panel, as many main panels do not have service wiring that is really heavy enough for this type of load.

You will also need heavy wiring between the circuit breaker and the system’s electrical relay box. The manufacturer recommends 4-gauge wiring, which is heavy and may in some cases be difficult to run.

Obviously, a great deal of planning and thought is required before installing a system of this capacity and with these electrical requirements.

On the plus side, the fully modular design allows the system to be mounted in a surprisingly small space, essentially little more space than is required by a modular 6-gph system.

Weight of the YM-200 is 83 lbs.

The manual includes excellent system schematics, and reasonably thorough instructions for installation, operation, and maintenance of the watermaker.

As you might expect, the size of the pumps and motors result in a fairly noisy system: 80 dB at a distance of 1' from the high-pressure pump—the big noisemaker in any system. Due to its weight, electrical needs, and noise, the best location for this watermaker is a sound-insulated engine room or compartment, as close as possible to the ship’s electrical supply.

Bottom Line: The best application for this system is a larger boat with existing electrical capacity, and lacks a genset or a means of installing an engine-driven watermaker.

With a list price of $3,500—which is sometimes discounted through dealers—this is not an expensive system. In fact, on a dollar cost per gallon of water produced per hour basis, this is the cheapest system of the entire lot to purchase. It is not an electrically efficient system, but if the maximum output in the minimum time is your primary criterion in a 12-volt watermaker, the Caribbean Technology is definitely worth considering.

Spectra 180
The Spectra 180, and a few variations on its basic version, are the only watermakers produced by Edinger Marine Services. It is radically different from other 12-volt watermakers, extracting a lot of freshwater with astonishingly low power consumption.

When you first see the Spectra 180, your first impression is that one component—a big DC motor to power the high-pressure pump—has been left out. In fact, the entire system is powered by a small 12-volt pump and motor—about 1/8-hp.—no larger than the water pressure pump on a 35-footer. This is possible due to the unique design of the Clark pump, a remarkably energy-efficient pump created specifically to power this watermaker.

The Clark pump is totally unlike any other high-pressure pump used in watermakers. To oversimplify, the Clark uses two opposing pistons and cylinders with a single connecting rod. System pressure is created by the connecting rod driving the piston into the opposite cylinder. Without a detailed technical explanation of exactly how any why this works, it is fair to say that compared to other methods of creating adequate pressure for reverse osmosis, this is a remarkably energy-efficient system.

The Spectra 180 is also different from other watermakers in that it uses a standard “full-size” membrane whose pressure vessel is just over 44" long—almost twice the length of the pressure vessel containing the 2521 membrane used by all the other high-capacity systems in out tests. Mounting this much longer pressure vessel may present problems in some boats. The Clark Pump housing itself is almost as long as the pressure vessel for a 2521 membrane.

According to the manufacturer, they have torn down Clark pumps after 3,000 hours of operation and found no significant wear. In any case, the pump is easy to overhaul in the field by a reasonably proficient owner. An overhaul manual for the pump is part of the system documentation, which is basic but adequate.

This is a modular system, with a remote control panel that can allow basic operation without direct access to the other system components. Total weight is about 51 lbs.

Our test system was a factory demonstrator, configured as a self-contained frame system with some performance compromises compared to the correct, conventional modular installation. Instead of a single large membrane, our test system utilized two 2521 membranes, similar in flux area to the larger membrane.

From a pure electrical efficiency perspective, the Spectra 180 was the most impressive watermaker we tested. With a current draw of 8.6 amps at 13 volts, our test unit pumped out fresh water at the rate of almost 9.5 gph-—almost as much as the Great Water system, which draws almost five times as much power. That’s only 11.8 watts per gallon, by light years the most electrically efficient machine in our test.

In addition, at a noise level of 65 dB, this was the quietest system.

The Spectra 180 is not perfect, however. The system runs at low pressure compared to other systems—just 600 psi with our 70°F water temperature—and the product water, although perfectly acceptable, had the highest total dissolved solids in our tests. Since product water quality can vary with different membranes, we are reluctant to attach much significance to this slightly lower water quality, which was still well within standards for drinking water.

We have some concerns about the relatively low feed water flow rate through the big membrane. The more water that passes over a membrane, the better it likes it, according to most manufacturers. The Spectra’s flow rate of about 90 gph is quite small for the large membrane, and we do not know how the longevity of the membrane might be impacted by this.

The ends of the main block of our system’s Clark pump were machined from bronze, and showed some signs of surface oxidation at the interface to the Delrin main block. According to the manufacturer, future editions of the Spectra will have stainless steel components in place of bronze.

Likewise, the pressure relief needle valve on our test system dribbled when it was barely cracked open. We were told that this component has also been re-designed.

Our test system utilized brass high-pressure fittings, rather than the type 316 stainless used by every other manufacturer. Some manufacturers claim that the only reason to use brass is to save money, while others admitted to us, a bit reluctantly, that they had never seen a brass high-pressure fitting with significant corrosion, and stainless was generally used for appearance and galvanic compatibility as much as for longevity purposes.

Given the cost of the Spectra 180, we think you should get type 316 stainless fittings, and type 316 pump block components. The price of the Spectra 180 is $4,650, the highest of any machine we tested. You pay a significant premium for a major increase in electrical efficiency. Service, parts, and options prices are similar to those of other manufacturers: $350 for a long-term offshore service kit, for example. The price of the installation kit—$275—strikes us as a bit high for such parts as the three-way servicing and diverting valves that some other manufacturers include in the price of the basic system.

According to the manufacturer, although the system is fully functional and in production, they are still looking at further developments, including a composite Clark pump that would have no metal components. Relatively few of these machines are in use in the field at this time, as the product is quite new to the market.

Bottom Line: The most attractive feature of this system is its energy efficiency. We are less impressed by its price, and by the fact that it would appear to be a system with some room for refinement. However, if being able to run a watermaker without running the engine at the same time is important to you, and if price is less important than electrical efficiency, the Spectra 180 would be the choice among the systems we tested.

Conclusions/Recommendations
Because virtually every cruising boat has different needs, priorities, and installation requirements, no single high-capacity 12-volt watermaker is going to fit the bill for every sailor. These are all well-designed, fully functional machines. Each has specific advantages and disadvantages, which we have described.

All meet their manufacturer’s performance specifications in terms of electrical consumption and product water output. Variances of +/- 10% to 15% from the manufacturer’s specifications for performance are normal.

The variations in product water quality we found are not significant. All the watermakers produce water that meets international standards for potability. The quality of the water will vary over time with any watermaker and with any membrane. A simple hand salinity tester—available from most watermaker manufacturers—is all that is required for routine checking of water quality. Most owners who use their watermakers daily don’t even bother testing salinity. They start the machine, let it run for a few minutes, taste the water, and if it tastes good, divert it to the tank.

All watermakers have similar maintenance requirements, and all we tested are reasonably easy to service. Your choice of a specific system will be largely the result of specific requirements for your boat and your cruising. The key questions are the amount and shape of space you have for the watermaker, the existing or planned electrical generating and battery storage capacity of your boat, and the amount of water you must make in a specific time frame.

All watermakers are maintenance-intensive. To a large extent, the long-term, hassle-free operation of a watermaker is a function of where and how it is used, and how religiously routine maintenance is performed. None of these machines will stand abuse.

A freshwater flushing system is an important component of a watermaker installation. Of the machines tested, only Village Marine and SK Engineering offer a ready-made freshwater back flush system as an option. While it is an easy system to design and build for anyone capable of installing a watermaker, it should be offered and recommended as an option by other manufacturers as well.

None of these systems is beyond the installation capabilities of a reasonably handy boat owner. If space permits, a totally self-contained system such as Village Marine’s Little Wonder will be slightly easier to install, but the total difference in installation time between self-contained and modular systems should not be more than a few hours unless there are vexing component mounting problems to solve. Plumbing and wiring connections are essentially the same for modular and self-contained systems, although a modular system with a remote panel will certainly take the longest time to install because of the number of individual components that must be placed.

All installations require attention to detail, particularly when it comes to wiring. We would not recommend you install a watermaker as the first major project you undertake on your boat, since it will require putting in a through-hull, installing heavy-duty wiring, and completing some plumbing that may in some boats be more difficult than it may first appear.

While all watermakers are covered by manufacturer’s warranties, all specifically exclude damage due to abuse in operation, poor maintenance, or improper installation.

A watermaker is not a use-it-and-forget-it product. It’s for those who live aboard. If you don’t use it regularly and maintain it properly, you are wasting your money, and you shouldn’t own one. On the other hand, if you are willing to accept the responsibility of maintaining a fairly demanding piece of equipment, a 12-volt watermaker can give you—particularly if you are a cruising sailor who desires long-term independence from shore—a degree of freedom you may not otherwise find.


Contacts- Edinger Marine Service, Inc., 298 Harbor Dr., Sausalito, CA 94965; 415/332-3780, fax 415/332-8527. Great Water, Inc., 5148 Peach St. Erie, PA 16509; 814/838-0786, fax 814/838-8700. Ocean Link, 52 Maritime Dr., Portsmouth, RI 02871; 401/683-4434. PUR, Recovery Engineering, 9300 75th Ave. North, Minneapolis, MN 55428; 800/845-7873, fax 312/315-5505. SK Engineering, 4256 N. US 1, Suite 1, Ft. Pierce, FL 34946; 800/489-0852, fax 561/489-0808. Village Marine Tec., 2000 West 135th St., Gardena, CA 90249; 800/421-4503, fax 310/538-3048.

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