Rainman Watermaker Autoflush System

Your Rainman watermaker is a very robust piece of equipment, but caring for certain aspects will prolong the usable life. If seawater is left for too long in your watermaker, planktonic organisms will die and rot. This can eventually damage the reverse osmosis (RO) membranes in your watermaker.

Our normal guidance is that if you are leaving your system for more than a day or two, you should flush the seawater out of the system with fresh water. After another week, you either need to fresh water-flush the system again, or pickle the system for longer term storage by adding a biocide to the fresh water flush. While this is a very simple process to execute, it is also one of the tasks that many customers prefer to have automated. Many people that have installed their Rainman watermaker prefer to have the system flushed weekly instead of pickling their system. Our Autoflush System is designed to ease the burden of remembering to perform this flush.

rainman autoflush system solid state timer

Solid-state timer

The Autoflush System incorporates a solid-state timer, a motorized valve, and an activated carbon filter to allow your boat’s fresh water supply to push fresh water from your boat’s tanks through your watermaker for a few minutes every seven days.  The one button programmable timer can be set between two and eight minutes flush cycle duration, depending on how strong your boat’s water pump is.  The activated carbon filter will neutralize chlorine that may be in your tank from municipal water sources.

Installation and operation

The timer and motorized valve operate from 12-24VDC. One side of the system is plumbed to your boat’s fresh water supply while the other side is plumbed into your Rainman pressure supply unit (PSU). The system is delivered with two activated carbon filter cartridges, which should last six months each.

During normal operation, you would simply push the autoflush button once after making water. The system will flush your watermaker with fresh water and reset the countdown timer for seven days.

If your boat loses power for some period of time, our timer has protection built in. Upon resumption of power, the timer will wait 15 seconds for other appliances to start, then trigger a flush and reset the countdown timer for 7 days thereafter.

If the system loses power during the flush cycle, the motor valve will close to ensure the fresh water tank does not drain.

Although the Autoflush System is sold as an option with new Rainman watermakers, it is fully compatible with older Rainman systems that have been installed.

Related products

Control Panel

The control panel retains the Rainman simplicity for which we are known, while adding a number of convenient features to allow for simpler access and remote control.

Plumbing Install Kit

If you plan to install your Rainman watermaker, the plumbing install kit includes the commonly required fittings and valves to assist with the installation.


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