Rainman DC Electric Water Maker


The DC Electric system is the Rainman watermaker that consumes the least power.

It’s a very simple and highly reliable system that can make up to 34 litres (9 gallons) of fresh potable water per hour.

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

Our 12VDC system is a great option if you don’t have AC power available to you but want to avoid the complexities and maintenance requirements of more efficient energy recovery systems.

battery watermaker
battery operated desalinator

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.

Unlike the AC (electric) or petrol (gasoline) powered Rainman Watermaker, the 12VDC is compatible only with the single 40″ RO membrane.

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With recent advancements batteries, solar, and wind power, it is easier than ever to have sufficient useable amp-hours available for running your appliances.

Our 12VDC system requires 410 watts, or about 30 amps, to operate.

battery powered desalinator
installed electric watermaker

Modular Installed or Portable

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.

It is worth noting that due to the lower output and shorter power cord of our 12VDC, most customers with this system will choose to fully install the watermaker.

rainman watermaker pickling bucket

Reverse Osmosis Unit

Due to the lower flow rate of the 12VDC PSU, only a single 40″ membrane RO unit is supported. This can either be in the Portable configuration with the blue case or Modular version with the easy mounting bracket.

This system will make 26-34 litres per hour (7-9gph).

More information about reverse osmosis »

reverse osmosis battery powered desalinator

Portable or Modular Installed

The system can be purchased either as the blue case version or in the Modular configuration for installation. The 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.

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marine watermaker battery powered

Features common to both Portable and Modular installed versions

Permanent magnet TEFC DC Motor
410 watts steady state power consumption
Current draw 30 amps
Power cord length: 1.4 metres (4.5 ft) including battery connectors
Plug type: Anderson Style
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
Sound levels – 58dB at 6 metres (20 ft) – see chart

Portable version specific features

Modular 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 – 40 lph (11 gph) product water flow meter, integrated in to RO case 0 – 40 lph (11 gph) 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 fitted with one way valve to remain primed, with detachable strainer 5 metre (16 ft) intake hose
3 metre (10 ft) brine waste discharge hose 6 metre (20 ft) brine waste discharge hose
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 230 x 240mm (18.5 x 9.1 x 9.5″)
Related RO weight
– Economy: 11kg (24lb)
Related RO weight
– Economy: 10kg (22lb)
Related RO dimensions
Economy: 1,180 x 250 x 130mm (46.5 x 9.8 x 5.1″)
Related RO dimensions (in mounting brackets)
Economy: 1,170 x 220 x 120mm (46.0 x 8.7 x 4.7″)
rainman watermaker control panel

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 Modular or Portablwe Rainman.

More information about the Rainman control panel »

rainman watermaker control panel


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.

More information about the Rainman autoflush system »

rainman autoflush countdown timer
rainman watermaker 12 volt accessories

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 Modular Rainman systems, but can also be a very useful option if you plan to install your Portable 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 »

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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 »

rainman watermaker spare parts

12VDC System Options Gallery

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Portable PSU

12VDC or 24VDC

high output desalination system
Portable RO

1 x 40″ Membrane

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Modular PSU

12VDC or 24VDC

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Modular RO

1 x 40″ Membrane