Overview
The original Rainman watermaker was our petrol (gasoline) powered system. In 2014, our first version of this system made the industry ask “Why didn’t someone think of a portable watermaker before this?”
This system requires no external power source, so long as you have fuel. It is ideal if you don’t have a generator and need to conserve your battery bank. Not relying on external power gives maximum flexibility for taking it ashore, loaning it out, or using it in emergency situations.
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 Petrol (Gasoline) Rainman system, each to achieve their own specific objective.
Power and Production Options
The heart of this system is the Honda GXH50 2.1HP engine, which is the same as that used in their 1kVA generator. It incorporates a tensioned belt drive system where the engine drives both an impeller lift pump and the General Pump high pressure pump. The fuel tank holds 700ml (1.5 pt) and will run for about 70 minutes, depending on fuel quality.
It is available with three different reverse osmosis (RO) membrane case configurations, with varying size and outputs.
Model |
Output |
Power |
|
|---|---|---|---|
| Portable - Controlled in case only | |||
| Petrol-140L Most Popular |
100-154lph 26-41gph |
Petrol/Gasoline 1 hr, 700ml |
|
| Petrol-75L | 55-82lph 15-22gph |
Petrol/Gasoline 1 hr, 700ml |
|
| Petrol-70L | 50-77lph 13-20gph |
Petrol/Gasoline 1 hr, 700ml |
|
Benefits of Petrol (Gasoline) Power
Petrol (gasoline) exists on most boats already, so there is good reason why you may consider using it to power your watermaker. Some of the key benefits of using a separate motor for your watermaker include:
- Simplicity – For a portable configuration, there are only two boxes to set up and no need for external electricity.
- Redundancy – If your generator / inverter fails, you can still make water.
- Efficiency – There are no conversion losses between mechanical and electrical energy. Depending on water temperature, and source water salinity, you would expect a fuel to fresh water production ratio of about 150:1.
- Security – If you are in an urban survival situation after a natural disaster, a portable generator has very broad utility and greater chance of being stolen, rendering an AC system useless.
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.
Specifications Comparison Table
The following table compares the specifications of the different Rainman Petrol (Gasoline) systems. It also has the option to bring other types of Rainman systems into the comparison.
Use “Select Columns” to choose systems for comparison.

