Ever Wondered About a Water Maker?

Our water maker removed from its snug position under the sink and looking a bit sorry for itself prior to overhaul. Photo by Sim Hoggarth

Have you ever wondered about a water maker? We did. Every time I lugged those jerry jugs aboard. Every time I ran across the bay to the water dock in the dinghy on a wild and windy day. Every time someone ran a tap for more than a few seconds. Every time the tanks got low.

We probably didn’t need to buy a new boat to get a water maker but that’s what happened. And I’m still wondering about a water maker! Now that we have one is it the right one for us? It seems there is quite a lot to consider – output, initial cost, physical size, power requirements, and ongoing running and maintenance costs. Having acquired our water maker, an older Katadyn 80e, with the boat and not really wanting to splash out huge sums of money for a different one, we’ve had time now to assess the pros and woes, and do a thorough rebuild.

We like that ours will run off the solar panels on a sunny day. If I was starting from scratch, perhaps I’d build something a little bigger but the efficiency of the Katadyn is hard to beat.

Be organized and methodical when you start dismantling. Photo by Sim Hoggarth

The sky’s the limit these days for big ships and shore-based reverse osmosis installations but for us, bearing in mind the other factors, our three gallons an hour is just enough. Our tanks hold 180 gallons and we use about six gallons a day. That means we can go up to six weeks on just one hour a day, or we can go indefinitely if we run it two hours a day. Of course, in practice we don’t run it every day, due to dirty harbors, lack of power, just too busy having fun, etc., but eventually we’ll find somewhere easy to top up the tanks alongside.

Water makers are pricey bits of kit, but for many cruisers the convenience makes it worthwhile. And the bigger the machine, the cost per gallon comes down considerably. But other factors come into play here, too. If you’ve definitely decided you need one then cost should not be the biggest factor; nor should ‘buy the biggest you can afford’.

Removing the pump assembly. Photo by Sim Hoggarth

Power requirements
Perhaps the most important decision to be made is how it will be powered. If you sit at anchor for extended periods, do you really want to run the engine almost every day to provide the electricity required or to operate an engine-driven pump? Do you have sufficient wind or solar power to do the job? Maybe you run the engine or generator every day anyway, which could supply extra power. For us, the best feature of our ‘little’ Katadyn is that thanks to some clever design features, whereby the rejected brine pressure helps drive the pump, it draws only eight amps and on a sunny day our solar panels can easily charge the batteries and make water for several hours.

Physical size
On most boats space is at a premium. Our unit fits nicely underneath the galley sink making good use of often wasted space. Close to a sea water supply, both the product and brine can easily be dealt with. Engine room spaces are best avoided as the membranes can foul more quickly in the increased temperatures.

Preparing to reassemble the membrane housings. Photo by Sim Hoggarth

Running costs
Day-to-day costs are just about zero as long as you’re not running the engine just to operate the water maker. Pre-filters should be changed regularly especially if you’re in a silty area. Fortunately they’re cheap; you can even wash them out and re-use them. But more extensive servicing and repair can be expensive and can vary greatly depending on the brand. Machines made up from generic components allow you to shop around and replace even major parts such as motors, pumps, membranes and even membrane housings at a reasonable cost. Conversely, parts for some popular brands—as we learnt to our cost—can be more than two or three times the price for equivalent components.

Refitting the drive motor. Photo by Sim Hoggarth

Having decided that our little Katadyn suited our purposes, I figured it was well overdue for a major overhaul. A couple of worsening leaks and falling product quality and quantity all pointed to a pump rebuild and, having no idea of the unit’s history, I decided to replace the membranes too. Most of the Katadyn water makers likely to be found on cruising boats are similar but small differences apply from model to model. All parts come with comprehensive fitting instructions making the work simpler than one might imagine. Maintenance is well within the scope of most practical boat owners. And that applies to most brands, not just the Katadyn. All the main parts come apart quite easily and then you can treat each bit as a separate task. For the pump rebuild, and membrane replacement, just be organized and methodical and maintain a really clean working environment. Contamination is your greatest enemy. Only silicone grease should be used.

In conclusion, are we pleased to be part of the water maker crowd? Absolutely! We like that ours will run off the solar panels on a sunny day. If I was starting from scratch, perhaps I’d build something a little bigger but the efficiency of the Katadyn is hard to beat. If you aspire to join the gang, then take time to consider your needs: input, output and power supply.


Sim Hoggarth is a British merchant navy marine engineer now cruising in the Caribbean with his wife Rosie on board their yacht Wandering Star.