A watermaker is the most divisive piece of kit on a cruising boat. Half the people I meet swear it transformed their cruising, the other half call it an expensive thing that breaks. After fitting one and living with it for two French seasons, I have landed somewhere in the middle, and the honest answer for France is more interesting than a simple yes or no.
Because here is the thing nobody says in the brochures: France is not the Caribbean. Fresh water is everywhere along this coast, the marina tap is rarely far, and that single fact reshapes the whole decision.
How a modern watermaker works
The principle is reverse osmosis. A pump forces seawater through a membrane at high pressure, the membrane lets water molecules through and rejects the salt, and you get fresh water out of one pipe and concentrated brine out of another. The old problem was that pushing water to that pressure ate enormous amounts of power, which is murder on a boat running off batteries.
Modern units solved this with energy recovery, capturing the pressure in the reject brine and using it to help pressurise the next slug of incoming seawater. The efficiency gain is dramatic and it is the reason a watermaker is even thinkable on a sailing boat today.
The numbers that matter
Let me give you real figures from current 12-volt units, because this is where the decision lives.
A compact energy-recovery watermaker producing around 30 litres an hour draws roughly 96 to 110 watts, which on a 12-volt system is about 8 to 9 amps. Run it for an hour and you make 30 litres for around 9 amp-hours. The most efficient small units now hit close to 2.75 watts per litre, so a larger model can make 40-plus litres an hour at similar power. Those are genuinely modest loads, the same order as a fridge.
That changes everything. A watermaker no longer demands a generator. It can run off solar and a decent battery bank, which is why the question has reopened for normal cruising boats.
What it costs in 2026
Money is where enthusiasm meets reality. A capable 12-volt energy-recovery watermaker is not cheap. A well-regarded compact unit sits around 6,000 euros, and a portable 12-volt system making roughly 34 litres an hour can run anywhere from 5,000 to 10,000 euros depending on options and install.
Then add servicing. Membranes need pickling if the unit sits unused, pre-filters need changing, and a neglected watermaker is a fast route to an expensive repair. If you leave the boat in France over winter you must plan for laying the unit up properly. None of this is hard, but it is a commitment, not a fit-and-forget purchase.
The reality check for France
Now the awkward question. Do you actually need it here?
On a French coastal cruise you are rarely more than a day from a marina with a hose. The cost of water at the tap is trivial, and many ports include it in the berthing fee. If your cruising is marina-hop to marina-hop, a watermaker solves a problem you do not really have. You will spend 6,000 euros to avoid filling a tank you could fill in twenty minutes for the price of a coffee. Look at what you actually get for the berth fee in my notes on water, electricity and showers in French ports before you spend.
The watermaker earns its keep when your cruising looks different. If you anchor for a week at a time off the Glenans, Belle-Ile or out in the calanques, never touching a pontoon, then water becomes the thing that drives you back to harbour before you want to go. A watermaker breaks that leash. You stay out as long as the food lasts, you shower freely instead of rationing, and the marina becomes a choice rather than a supply run.
So the real question is not "is a watermaker good" but "do I anchor out for long enough that water, not weather or food, is what ends the stay?" If yes, fit one. If no, save the money.
The power conversation you cannot skip
A watermaker is a load, and loads need a power system that can feed them. This is where the watermaker decision collides with every other electrical choice on the boat.
Making 30 litres a day costs you around 9 amp-hours, which sounds trivial until you stack it on a fridge, instruments and devices. The watermaker tips a marginal power budget into deficit. Before you buy one, do the power budget I described in power management on a French coastal passage and make sure the supply can carry the new load.
In practice that means two things. First, generous solar, because the watermaker is happiest running at midday when the panels are making their best power and you can turn sun straight into fresh water. I sized panels for exactly this in solar panels for cruising France. Second, a battery chemistry that delivers and refills fast, which is lithium. Running a watermaker off a tired lead bank is a recipe for flat batteries and frustration, and I made the case for the switch in lithium vs agm boat batteries for a French summer.
The pattern is consistent. A watermaker is the top of a pyramid. The base is solar and lithium, and if the base is not solid the watermaker just exposes the weakness.
Installation and the things that break
A watermaker is plumbing, electrics and chemistry in one box, and each part has a failure mode. The seawater feed needs its own dedicated through-hull and a good pre-filter, because anything that reaches the membrane shortens its life. The high-pressure pump is the heart and the expensive part, and it hates running dry, so the install must guarantee a flooded feed. The membrane itself is happy in regular use and unhappy sitting idle, which is why pickling matters the moment you stop using it for more than a few days.
For a visiting cruiser the idle problem is the real one. If you leave the boat in France for a fortnight mid-season to fly home, or lay it up for winter, the watermaker needs pickling with a biocide or it grows things that ruin the membrane. Build that habit in from day one. The boats that have trouble are almost always the ones that used the unit hard for a month, left it untouched, and came back to a dead membrane and a four-figure repair bill.
There is also a water-quality point worth making. A watermaker pulls in whatever is around the boat, so you do not make water inside a marina or near a river mouth where the inlet is full of fuel sheen, sewage and silt. You make it offshore or in a clean anchorage with good circulation. That suits French cruising well, since the clean anchorages are exactly where you want the water anyway, but it is a discipline, not a free tap you turn on anywhere.
My honest recommendation
For a typical French coastal season of marina-hopping with the occasional night at anchor, skip the watermaker. The water is too easy to get and the money is better spent elsewhere on the boat.
For a cruiser who anchors out for long stretches, who treats the marina as an occasional indulgence rather than a base, and who has already built a solar-and-lithium system that can feed it, a watermaker is one of the great quality-of-life upgrades. It does not save money against a French marina tap. It buys you something money usually cannot: more days in the anchorage you did not want to leave.
Be honest about which cruiser you are. Mine spent its first season barely used, because I kept ending up alongside for one reason or another. Its second season, when I finally committed to anchoring out, it changed the whole shape of the summer. The kit was the same. I was the variable.
