Systems
Water
Make fresh water, anywhere.
Water is the dependency that most often ends a trip before the batteries do. A watermaker and proper treatment turn the tank from a countdown into a non-issue.
A pump pushes seawater against a membrane that lets water through and holds the salt back. Fresh water comes out one side, concentrated brine goes over the other.
In full: a high-pressure pump forces seawater through a semi-permeable membrane that rejects dissolved salts and most contaminants, giving fresh product water on one side and concentrated brine on the other.
The catch is energy. Pressurising seawater is hard work, and on a battery-powered boat or expedition vehicle every amp-hour counts. Energy-recovery designs attack that directly, reclaiming pressure from the outgoing brine and feeding it back into the feed side, which cuts the power needed per litre. That is the difference between a watermaker you can run off solar and one that means starting the generator.
The watermaker makes the water. Treatment is what makes every tap on board trustworthy — including the water you took on from a tank or a shore hose.
Watermaker product water is low in dissolved solids but still benefits from defined treatment for taste, for stored-water management and for biological safety. Any boat or vehicle also carries tank or shore water, which needs the same protection and rarely gets it.
Treatment covers filtration, disinfection and stored-water management, and the right approach depends on the source, how long water sits in the tank and the standard you need to meet.
The installation matters as much as the unit.
Membrane production varies with feed-water temperature and salinity, so real-world output depends on where you actually cruise — the same unit yields more in warm water than in cold.
Clean, well-supported plumbing, a protected intake, accessible pre-filters and a sensible service position are what decide whether the system still performs in three seasons or gives up in three months.
The full path from raw seawater to a tap you can trust.
What to get right
- Size output to demand, not to the biggest number on the datasheet. Estimate daily consumption per person, add a margin for guests and washdown, and pick a unit that meets it inside a comfortable daily run window rather than running flat out.
- Match the watermaker to your power reality. On a battery-led, solar or sailing platform, prioritise energy-recovery designs that produce more water per amp-hour. The cheapest unit to buy is rarely the cheapest to run.
- Plan the installation around servicing. Pre-filters, membranes and the high-pressure pump all need routine access, so put the unit where filters can be changed and the system flushed without taking joinery apart.
- Protect the membrane with proper pre-filtration and flushing. Sediment and biofouling are what kill membranes early. A clean intake, staged pre-filters and a disciplined fresh-water flush regime extend membrane life considerably.
- Treat the whole water path, not just the watermaker. Pair RO production with filtration and disinfection for tank and shore water, so everything that reaches the tap meets the same standard.
What this covers
- Reverse-osmosis watermakers
- Energy-recovery desalination
- Drinking-water treatment
Frequently asked questions
What is an energy-recovery watermaker, and why does it matter?
It is a reverse-osmosis desalinator that reclaims pressure from the brine it discharges and returns that energy to the feed side, so it needs less power for every litre it makes. On battery, solar or sail-powered platforms that means more water for the same draw on the bank, which is usually the deciding factor on off-grid and long-range boats and vehicles.
How much water can a watermaker produce?
That depends on the unit and on the conditions. Membrane production varies with feed-water temperature and salinity, so the same watermaker yields more in warm tropical water than in cold. Size the system to your estimated daily consumption plus a margin, and confirm the expected output against the specific model and the waters you actually cruise.
Do I still need water treatment if I have a watermaker?
Yes. Watermaker product water is low in dissolved solids, but treatment still matters for taste, for stored-water management and for biological safety. Every boat and vehicle also carries tank or shore water that needs protection. A complete system pairs RO production with filtration and disinfection across all sources.
What maintenance does a marine water system need?
Regular pre-filter changes, fresh-water flushing of the membrane, membrane care or replacement over time, and servicing of the high-pressure pump. Keeping the intake clean and following the manufacturer's flush and lay-up routine is the single biggest factor in membrane life, so design the installation to make those jobs easy rather than dreaded.