Rainman AC (Electric) Watermaker

The AC system is by far our most popular watermaker. It’s a very simple and highly reliable system that can make up to 140 liters (37 gallons) of fresh potable water per hour.

Options exist for this system to be run as portable without any plumbing or plumbed in with a minimum footprint installation.

Our AC system is a great option when you want to make a lot of water quickly and get back to enjoying yourself.

ac electric watermaker on yacht

Power options

With recent advancements in generators, batteries, and solar power generation, you have several options for powering the AC system.

Originally designed to run off of a minimum of a Honda 2kW generator, it will be easily powered by your inbuilt generator or a quality 2kVA inverter.

Choose either a 230VAC/50Hz or 115VAC/60Hz option to suit the power available in your situation.

You should ensure you know what power (voltage and frequency) you have available when ordering a Rainman AC watermaker.

Voltage and frequency considerations

Rainman AC systems come in either 230VAC / 50Hz or 115VAC / 60Hz. This covers the vast majority of AC power set ups around the world (the Philippines is an exception). These systems are almost identical, except for two factors.

The AC induction motors are manufactured for either 230VAC or 115VAC.
The shafts on the high pressure pumps have different throw lengths, optimizing the system for either 50Hz or 60Hz operation.

Running 230VAC/50Hz System At 60Hz

The motor will spin 20% faster. This means the pump is moving 20% more water, the AC motor is doing 20% more physical work, and is drawing a higher current. Increased current means it is operating at higher power and will eventually overheat the motor windings, causing permanent motor failure.

Running 115VAC/60Hz System At 50Hz

The motor will spin 17% slower. This means the pump is moving 17% less water, the AC motor is doing 17% less physical work, and is drawing a lower current. This lower flow rate will slightly decrease the product water output and slightly increase the TDS of the product water, but will not harm the system.


We keep our watermakers as stock items ready for immediate shipment. However, if you have a need for either a 230VAC/60Hz or a 115VAC/50Hz system, we can build it as a custom configuration. It will take two extra days to fit into our production schedule. A token charge will be made for the custom build.

We can create this custom build for the naked configuration. The portable watermakers in the blue shell are designed to be moved between boats easily and not appropriate for custom configurations.

Installed or portable watermaker

Our traditional system in the blue case can be used as either portable or installed. If you wish to install it, it becomes a two-box installation.

men carrying portable watermakers in marina

Reverse Osmosis (RO) options

You have three basic reverse osmosis (RO) options, depending on your water requirements, space available, and budget.

All three RO options are compatible with the AC PSU and available in either the cased and naked configurations.

High Output

• 100-140 lph (26-37 gph)
• 2 x 40″ RO Membranes

Our most common configuration with the AC system due to having the highest output and best overall value. Twice the output of the other options.


• 50-70 lph (13-18 gph)
• 2 x 21″ RO Membranes

A great option if you are physically space constrained. Also common if this is a backup system on a larger vessel as it can be stowed in smaller spaces.


• 50-70 lph (13-18 gph)
• 1 x 40″ RO Membrane

Our entry level water maker system is best suited for those on a budget. It can be upgraded to a high output system at a later date by adding a second membrane.

Cased or naked options

The system can be purchased either as the traditional blue case version or in the Naked configuration. The pricing, performance and power consumption are identical between the two options, so your specific requirements control which is best suited for your application.

The table below summarizes the differences between the two options.


  • 1.5 HP totally enclosed fan cooled (TEFC) induction motor
  • 1250 watts steady state power consumption
  • Current draw 6 amps (230VAC) or 12 amps (115VAC)
  • Power cord length: 3 meters (10 ft)
  • Plug type choices: US (NEMA 5-15), Australian (AS/NZS 3112), UK (BS 1363), Europe (CEE 7/7)
  • Integrated flexible impeller lift pump uses non-proprietary impeller
  • 2 meter (6 ft) maximum lift above sea level
  • General Pump WMR 316 stainless steel high pressure triplex plunger pump
  • Integrated General Pump 316SS/ceramic relief valve to prevent overpressurisation
  • Sound levels: 62dB at 6 meters (20 ft)


ac electric watermaker - cased option


  • Case of sturdy injection molded polypropylene
  • PSU storage/mounting seat: fiberglass reinforced nylon with strap
  • RO Case (mountable if desired): rotomolded polyethylene
  • Plumbing installation kit at extra cost
  • Single 10″ x 2.5″ non-proprietary 5 micron pre filter to remove sediment mounted on PSU
  • 0 – 150lph (40gph) product water flow meter, integrated into RO case
  • Valve / gauge control assembly integrated into RO case
  • 5 meter (16 ft) intake hose fitted with one way valve to remain primed, with detachable strainer
  • 3 meter (10 ft) brine waste discharge hose
  • PSU weight: 24kg (53lb)
  • PSU Dimensions: 600 x 375 x 270mm (23.6 x 14.8 x 10.6″)

Related RO weight:
– High Output: 23kg (51lb)
– Compact: 14kg (31lb)
– Economy: 11kg (24lb)

Related RO dimensions:
– High Output: 1,180 x 250 x 130mm (46.5 x 9.8 x 5.1″)
– Compact: 690 x 220 x 150mm (27.2 x 8.7 x 5.9″)
– Economy: 1,180 x 250 x 130mm (46.5 x 9.8 x 5.1″)

ac electric watermaker - naked option


  • No shell
  • PSU easy mounting kit: fiberglass reinforced nylon for high rigidity and tensile strength
  • RO easy mounting kit: fiberglass reinforced nylon for high rigidity and tensile strength
  • Plumbing installation kit included with purchase
  • Single 10″ x 2.5″ non-proprietary 5 micron pre filter to remove sediment with SS316 mounting bracket
  • 0 – 150lph (40gph) product water flow meter, with SS316 mounting bracket
  • Valve / gauge control assembly at end of 5 meter (16 ft) high pressure hose for remote mounting
  • 5 meter (16 ft) intake hose
  • 6 meter (20 ft) brine waste discharge hose
  • PSU weight: 23kg (51lb)
  • PSU Dimensions: 470 x 270 x 240mm (18.5 x 10.7 x 9.5″)

Related RO weight:
– High Output: 22kg (49lb)
– Compact: 13kg (29lb)
– Economy: 10kg (22lb)

Related RO dimensions (in mounting brackets):
– High Output: 1,170 x 220 x 120mm (46.0 x 8.7 x 4.7″)
– Compact: 670 x 220 x 120mm (26.4 x 8.7 x 4.7″)
– Economy: 1,170 x 220 x 120mm (46.0 x 8.7 x 4.7″)

Optional accessories for your Rainman Watermaker

Control Panel

The control panel retains the simplicity that Rainman is known for, while adding a number of features to allow for simpler access and remote control.

Autoflush System

The Rainman watermaker is a very robust piece of equipment, but caring for certain aspects will prolong the usable life – try the Autoflush System!


As your membranes age, the TDS (total dissolved solids) of the product water increases. A hydrotester will measure the water quality.

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