Never run out of fresh water again.

Nash Marine can provide you with a compact watermaker system, designed to generate a fresh potable water supply from seawater.

New to Nash Marine Sales – Rainman Watermakers

Never run out of fresh water again, when out on your boat. A fresh approach to saltwater desalination.

With a Watermaker, you no longer need to rely on onshore fresh water supplies. This innovation extends your travel range, boosts your independence, and significantly enhances onboard comfort.

There are many Watermakers out there in the market, but the Rainman Watermaker is an Australian-made brand and is the most compact, versatile and price effective solution.

They are compact and can be installed in a minimum footprint configuration. The layout is customisable to fit your engine room, allowing the Pressure Supply Unit (PSU) and Reverse Osmosis Unit (RO) to be positioned separately to suit your space requirements (see example below). We use only top-quality components from the best manufacturers in the build process.

AC (Electric) Watermaker

The AC system is by far the most popular Watermaker. It’s a very simple and highly reliable system that can make up to 140 litres of fresh potable water per hour.

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

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.

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. 

More information about the Rainman 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 »

Modular Watermakers

  Most Popular
115VAC or 230VAC
1,250 watts
2 x 40”AU$ 8,449

Options for Modular Systems

Control Panel – recommended, but not requiredAU$ 936
Autoflush – recommended, but not requiredAU$ 550

Detailed Watermaker Schematic

Schematic Explained

  1. An impeller lift pump draws sea water up to the pressure supply unit and creates positive pressure for the high pressure pump.
  2. The pre-filter removes particulates larger than 5 microns from the water.
  3. A plunger pump pressurises the system for the reverse osmosis membranes to operate.
  4. The relief valve only opens if the control valve is closed excessively.
  5. A high pressure hose carries filtered sea water to the reverse osmosis (RO) membranes.
  6. Multiple membranes are connected in series (double RO membrane configuration).
  7. The membranes extract approximately 20% of the water from the pressurised seawater stream.
  8. The pressure control valve at the end of the system is used to set system pressure to 55 bar (800 psi).
  9. Brine water is released to the sea while fresh water is routed to your drinking water tank.
  10. Both the lift pump and high pressure pump are powered by either a reliable Honda 50cc engine or a fully sealed electric motor.

Operating The Installed A/C Watermaker

  1. Turn On the Power: Switch on the boats generator or have access to shore power. This will provide power to the Watermaker system.
  2. Ensure that the intake 3 way valve is turned to ‘sea water intake’ position. Ensure that any other valves in the intake plumbing are open and that the strainer is free of blockage.
  3. Ensure that the brine output is free from blockage.
  4. Ensure that the product water output is directed to ‘test’ and not to a water tank.
  5. Set the pressure control valve to fully open position (anti-clockwise).
  6. Switch on the Pressure Supply Unit.
  7. Water will start flowing out the green brine output water hose. Wait until the stream of water is free of bubbles. Upon first use, it may take up to 15 seconds to see water come out of the green hose.
  8. Gradually close the pressure control valve on the reverse osmosis unit by turning clockwise until the pressure gauge reads 55 Bar (800 psi). The correct pressure is indicated by the dark green area on the pressure gauge dial. For maximum membrane life, take about one minute to build to full pressure. Within 15 seconds water will start flowing out the white product hose.

Note: the clear liquid inside the pressure gauge is glycerine. This is to reduce vibration inside the gauge and ensure long and reliable service. It is normal to see a large bubble inside the gauge.

If you are using your Watermaker for the first time, run for at least half an hour to flush all preservatives from the system.

  1. Every time you use the unit, let fresh water flow out the white product hose for approximately 60 seconds to clear water or pickle solution that may be in the system. You should test the product water at this point by taste or with a TDS hydrotester.
  2. When the product water is pure, direct the product water hose into a fresh water tank and allow the system to run uninterrupted until full. Check the pressure gauge approximately every ten minutes. Although the ideal pressure is 55 Bar (800 psi), the acceptable range is between 51-58 Bar (750-850 psi). A small amount of pressure drift is normal. Adjust if necessary.
  3. If you are desalinating brackish water, or water that you suspect might be lower salinity than normal sea water, check that the product water flow rate is no higher than the recommended maximum for your system using the flow meter. See the section Desalinating Brackish Water for more details.
  4. Use the white 10 metre (30 foot) product water extension hose to fill multiple tanks without the need to move the desalination system. Use the push-fit joiner provided.

Product water flow will vary depending on several factors, including temperature and salinity. Warmer or lower salinity water will lead to higher levels of product water output. Natural membrane variability and other factors will play a role in product water output.

As a guideline every degree Celsius increase in water temperature, product water flow increases approximately 3%.

Once operating you can then leave it for as long as needed.

Call Now To Find Out More 02 9979 6500

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