Keeping things fresh: Essential water maker maintenance

The only job of a water maker is turning water that is unfit for human consumption into clean, fresh drinking “potable” water, using anything from brackish through to ocean water.

The way the water maker does this is using a process called reverse osmosis, where liquids flow from a less concentrated (read that as water mixed with salt) state to a more concentrated (pure water minus the salt) state.

When it is working, this is a very reliable method of producing pure fresh water. However, to keep it working, some maintenance required on a weekly, monthly and yearly schedule. You will also need to know how to maintain the water maker’s pre-filters as needed – with where you anchor likely to have the biggest impact.

There are signs that your water maker is starting to fail. The most obvious is that the salt content of the water it produces starts to rise, giving the finished product a brackish taste. Your unit should detect this and flash a warning light. One, or both, of the pumps may also fail to fire up.

However, one of the best, and easiest, forms of maintenance is to use the water maker regularly. “Water makers, like most marine-related products, love to be run,” Errol Cain, whose Gold Coast-based company, Australian Marine Wholesale, regularly services the units, said.

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“It’s important to regularly run and maintain a water maker for efficient and reliable operation. Regular running stops seals hardening, keeps pumps lubricated and membranes wetted,” he said.

Here’s the boatsales.com.au guide to keeping your water maker fresh for as long as possible.

Owners should perform a freshwater flush at least once a week. Most modern units will do this automatically after a unit has run and made water, and the system will automatically re-flush every seven days.

More basic units will need to be manually flushed with freshwater. This is vitally important to remove the small marine organisms that, as they grow, can pierce the tightly wound membrane used in the reverse osmosis process.

Each month boat owners should check the water maker’s sea strainer for signs of seaweed sucked up into the system, or other foul. A good time to do this is every time the engine’s sea strainers are checked.

You may need to perform more regulars checks if water is being made in high-weed areas such as Moreton Bay, where the risk of sucking foul into the system is higher.

A full service should be undertaken on a water making system once a year. Depending on the type of unit, this will include items such as the high-pressure pump’s oil, fresh water flush and product charcoal filters. All hoses, hose clamps and fittings should also be inspected.

Biennial maintenance

Every two years the membranes should be removed and treated with a good quality cleaner to flush out impurities and rejuvenate their efficiency. Looked after correctly, membranes should last eight to 10 years before needing replacement.

The pre-filters used in modern water makers (normally with holes measuring either 5.0 microns or 20/25 microns, or about the same as the diameter of a human hair) do a wonderful job of removing particles from the water before it reaches the membrane. Because they catch unwanted bits from the water, they will block up from time to time.

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Most water making units have high and low pressure switches to shut the unit down when the membranes become fully blocked, so no damage is done. A simple filter change is all that is required to continue making water.

Clearly, the cleaner the starting water is, the longer the filters will last. If water is to be made in enclosed waterways, high tide is best time for water making as it will help to extend the  life of the pre-filters.

If a unit has a media filter fitted in front of the membranes – a small sand filter similar to the ones used to clean pools – it should be back-flushed each time before the unit is used each time. This will also help to extend the working life of the fine membranes.

When it comes to running a water maker, there are a couple of important rules you should always adhere to:

“The water maker is something many skippers forget to check when planning for a long passage,” Cain said. “At Australian Marine Wholesale, we receive many last-minute, urgent call outs after someone says ‘Please help, our water maker won’t run’.

“Had all the regular maintenance and checks been carried out, this last-minute urgency would have been avoided,” he said.