Watermakers: Yes? No? Maybe?

Learning Center

At the recent Fountaine Pajot dealer meeting we had a great opportunity to meet with the developer/inventor/CEO of the watermaker chosen by Fountaine Pajot. Here’s the information right from the horses’ mouth. Also included, our discussion of the pros and cons of installing a watermaker on a boat set up as a business — now, vs. pre-plumbing and pre-wiring for one to be installed later.

Watermakers can make your life easier on board, not only providing safe, pure drinking water, but also plenty of water for bathing, dishwashing, clothes washers and even for electric freshwater heads. The longer you’re aboard at a time, and the further afield you cruise, the more important they become.

What is a watermaker?

In it’s simplest terms, watermakers use the process called reverse osmosis. This is not just a filter!

Imagine you have salty, or even polluted water and want to convert it to pure drinking water? The reverse osmosis process concept is that you use a high-pressure pump to force the water through a filter (permeable membrane) with the smallest holes you can imagine — so small that only the smaller water molecules can get through. The salt molecules (and other pollutants) are too large and are blocked and flushed away, as simple as that.

Planning for your watermaker

This description assumes that you are not just looking for survival, but rather, instead, for a substantial, reliable supply of high-quality water for drinking, bathing, washer/dryer, freshwater heads, perhaps, even a dishwasher and periodic fresh water deck/rig rinsing.

Watermakers come in relatively compact, all-in-one modules, or multiple modules, which can fit in multiple spaces when space is more limited. Both the main unit and elements as well as the pre-filters need easy access.

This is definitely an option to be discussed with our commissioning manager/engineer who will want to discuss your individual situation, plans, and expectations.

Typical requirements (Moderately generous use)

  • 15 liters/hr per person — approximately 8 gallons/hr or 96 gallons per day
  • 30 liters/hr for 2-3 — 4 gallons/hr or 192 gallons per day
  • 65 liters/hr for 4-8 — 17 gallons/hr or 400 gallons per day

We offer custom installations, primarily with the Fountaine Pajot supplied, SLCE Aqua-base ecosystem (12V) with outputs up to 400 gallons/day, or the Spectra system installed by our commissioning yard, with similar outputs. Both include automatic operation, prefiltering and maintenance cycles (automatic pickling and back-flush).

Considerations for your watermaker

If you keep your boat in a major port or harbor, either full-time or part-time, pollutants and especially oil in the water may destroy the element at worst, or cause clogging and failures of the pre-filters, which may also damage the main element (Cost about $800-$900 per main element, and you will have one to four, typically.)

Maintenance and costs

If you go more than 3 weeks at a time without using the watermaker, it will likely need to be “pickled”— decommissioned in effect (Using a biocide like that offered by the supplier). Even with automatic cycles, this takes some planning and makes it much less practical to have a watermaker that’s infrequently used. Flushing and backflushing should be done if it’s not used 3 days to 3 weeks. Prefilters need to be regularly checked and replaced (a lot less expensive than replacing the main element!)

There is also the need to winterize your watermaker if you don’t head south during the cold months.

Installations on a Charter Boat

  1. Bareboat Charter. For the above reasons, it doesn’t make sense to install a watermaker on a bareboat (boat without full-time crew). An owner can’t rely on charterers to do the necessary monitoring, back-flushing, etc. and even the best of management companies, where personal are not on the boat continuously, shouldn’t be expected to keep up with the maintenance demands and, remember, when a mistake is made and you damage the main element–that/s $800 per cylinder–your expense!
  2. Crewed Boat Chartering. In the case where you’re considering a fully-crewed boat, with a more or less full-time crew — if they are properly instructed and/or knowledgeable and diligent this option should be seriously considered and, in fact, should probably be considered essential in order to be competitive in this market.

Why use a DC version?

We can do AC or DC, dual-voltage watermakers as a boxed complete unit (where there is space) or installed as individual modules where there is not.

Our primary reason for recommending a DC unit is that in general, you have many sources of power for DC and are limited to running the generator, or shore power for AC. With DC, you generally will be able to keep your batteries charged and the watermaker running with the various DC input systems:

  • Engine alternator(s)
  • Generator
  • Charger at the dock or from the generator
  • Solar cells
  • Wind and/or water generator


Of all of the options you might be considering, the watermaker requires careful thought, planning, and professional installation. In general, this option is not so practical for a bare-boat charter boat, but if you are considering converting to personal use later, we offer the option to pre-plumb and pre-wire for it during commissioning.

If your planned use meets the guidelines discussed here, this option could easily prove to be one of your most prized choices and your crew will love you.


Useful links


Eric Smith

Senior Sales Consultant, Partner
More from Eric >> Boat Business Webinars, Videos, Blogs, Learning Center and more.

DisclaimerThe information, viewsopinions, and conclusions expressed in any article, blog, video, or other form of media posted or linked herein are those of the authors and do not necessarily reflect the views of Atlantic Cruising Yachts, LLC.  Nothing contained herein has been approved or otherwise endorsed by Atlantic Cruising Yachts, LLC and such company shall have no liability for any content.

ESE, LLC is totally responsible for the content of this article. We are not tax advisers. You should obtain tax advice from a professional tax adviser for any matters relating to setting up a business, or tax implications.