Rainman Water Makers Home

Fresh Water Anywhere

AC Electric, Petrol (Gasoline) and 12VDC Watermakers

Portable and Installed models available

A fresh approach to saltwater desalination. 

Rainman Watermakers are a compact system designed to generate a fresh potable water supply from seawater. They can be installed in a minimum footprint configuration or kept portable for maximum flexibility.
Rainman use only top quality components in the build process from the best manufacturers: Honda, General Pump, Filmtec, and Noshok.
Our filters, membranes and replacement parts are non-proprietary for ease of service worldwide.


Two Components – One Watermaker

The system is made up of a pressure supply unit (PSU) and a reverse osmosis unit (RO).

Both parts are required to make a complete watermaker. The PSU lifts the seawater, filters out the sediment and puts the system under high pressure, while the RO unit extracts fresh water from the stream of pressurised seawater.

Most of the water goes out to waste as brine output, while about 20% of the volume is extracted as fresh potable water for your tanks.

Different RO options exist for you to select with your AC Rainman system, each to achieve their own specific objective.


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.

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. Various approaches that can be utilised include:

  • Keep it portable, pulling it out and setting it up each time you wish to use it.
  • Leave the unit in a locker, but pull out the hoses and throw overboard to make water, avoiding the need to move the system around on your deck.
  • Keep the system portable, but use a cam-lock fitting to temporarily plumb the system into a teed deck wash fitting. This gives the benefits of an installed system while using your portable unit while underway.
  • Fully plumb the system in, including the autoflush system.

Reverse Osmosis 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.

desalination reverse osmosis

Portable Case or Naked Installed 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 summarises the differences between the two options.

Features common to both Cased and Naked versions

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 metres (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 metre (6 ft) maximum lift above sea level
General Pump WMR 316 stainless steel high pressure triplex plungerpump
Integrated General Pump 316SS/ceramic relief valve to prevent overpressurisation
3 metre (10 ft) LDPE food grade product water hose, with 10 metre (33 ft) extension (8mm OD)
Sound levels – 62dB at 6 metres (20 ft) – see chart

Cased version specific features

Naked version specific features

Case of sturdy injection moulded polypropylene No shell
PSU storage/mounting seat: fibreglass reinforced nylon with strap PSU easy mounting kit: fibreglass reinforced nylon for high rigidity and tensile strength
RO Case (mountable if desired): rotomoulded polyethylene RO easy mounting kit: fibreglass reinforced nylon for high rigidity and tensile strength
Plumbing installation kit at extra cost Plumbing installation kit included with purchase
Single 10″ x 2.5″ non-proprietary 5 micron prefilter to remove sediment mounted on PSU Single 10″ x 2.5″ non-proprietary 5 micron prefilter to remove sediment with SS316 mounting bracket
0 – 150lph (40gph) product water flow meter, integrated into RO case 0 – 150lph (40gph) product water flow meter, with SS316 mounting bracket
Valve/gauge control assembly integrated into RO case Valve/gauge control assembly at end of 5 metre (16 ft) high pressure hose for remote mounting
5 metre (16 ft) intake hose (1/2″ ID) fitted with one way valve to remain primed, with detachable strainer 5 metre (16 ft) intake hose (1/2″ ID)
3 metre (10 ft) brine waste discharge hose (10mm OD) 6 metre (20 ft) brine waste discharge hose (10mm OD)
PSU weight: 24kg (53lb) PSU weight: 23kg (51lb)
PSU Dimensions: 600 x 375 x 270mm (23.6 x 14.8 x 10.6″) PSU Dimensions: 470 x 270 x 240mm (18.5 x 10.7 x 9.5″)
Related RO weight
– High Output: 23kg (51lb)
– Compact: 14kg (31lb)
– Economy: 11kg (24lb)
Related RO weight
– High Output: 22kg (49lb)
– Compact: 13kg (29lb)
– Economy: 10kg (22lb)
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″)
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″)

Control Panel

The optional control panel provides a remote management capability for your installed Rainman watermaker. It’s a highly presentable and functional add-on component that will enhance your Rainman user experience. 

It is an injection moulded ASA acrylic panel that remains true to Rainman’s reputation of elegant simplicity. 

  • Integration with the Rainman autoflush system, triggers flush cycle after powering the watermaker off.
  • Built in tri-colour LED salinity sensor indicates when water is good to route to your tank.
  • Can be installed flush mounted, standalone with the included enclosure box, or even externally with the optional hatch.
  • Simple installation with no high pressure fittings or high voltage wiring.
  • Backwards compatible if you already have an installed electric naked or cased Rainman.



Your Rainman watermaker is a very robust piece of equipment, but caring for certain aspects will prolong its life. Regularly flushing your Rainman with fresh water will maximise the life of your watermaker membranes.

The optional autoflush system incorporates a solid state programmable timer that will flush your Rainman watermaker after each use and every seven days thereafter. It incorporates built in protection if your boat loses power during or between flush cycles.


Optional Accessories

While the base system will be sufficient for many customers, a number of options are available to get more out of your Rainman watermaker.

  • The plumbing installation kit is included with the Naked Rainman systems, but can also be a very useful option if you plan to install your Cased Rainman units.
  • A hydrotester will give you indication of the total dissolved solids (TDS) so you can know how your membranes are ageing.

Rainman desalinator optional accessories »

Spares and Consumables

Your new Rainman system will arrive with enough spares and consumables to keep you going for a while, so most customers do not need to order more with initial purchase. There are a variety of items you will need over time to keep your system running for many years.

Rainman Watermaker spare parts and consumables »

AC Watermaker System Options Gallery

rainman watermakers electric model psu case
Cased PSU
rainman watermakers electric case reverse osmosis
Cased High Output RO
rainman watermakers electric compact reverse osmosis case
Cased Compact RO
rainman watermakers electric reverse osmosis economy case
Cased Economy RO
rainman pressure supply unit naked
Naked PSU
rainman installed electric watermaker reverse osmosis high output
Naked High Output RO
rainman installed electric watermaker reverse osmosis compact
Naked Compact RO
rainman installed electric watermaker reverse osmosis economy
Naked Economy RO

Contact form