At home, the water filters you use only remove impurities and contaminants from freshwater. Filtering and purifying salt water is quite different from filtering freshwater.
You need special filters to remove the salt, bacteria, and any other dissolved contaminants common in salt water.
The process of removing salt from salt water, which typically comes from the ocean, is called desalination. The devices that desalinate salt water and turn it into drinkable water are called desalinators.
However, on boats and ships, these water purifiers are commonly called watermakers.
In this post, we’ll talk about the effective filtration method of salt water and list the best water purifiers for it, many of which are designed for boats, sailboats, and yachts.
However, some portable desalinators can really be used anywhere there’s salt water as long as the feed water pressure is high enough.
Every filtration system and filter type has its unique merits and can remove particular contaminants from water. For instance, sediment filters can trap sand, debris, and other particulate matter. Similarly, activated carbon filters can absorb chemicals like chlorine.
However, not many filters can successfully remove salt from salt water, along with other possible impurities. The best and most common salt water filtration system is reverse osmosis.
Distillation is another method of purifying salt water and making it drinkable. However, it’s a very expensive method that’s more suitable for large industrial scale filtration.
For those who are unfamiliar with the Reverse Osmosis (RO) filtration system, it’s a highly effective purification system where water passes through a very fine membrane at pressure. Only pure water molecules can pass through this barrier, leaving behind solvents in the water, including salt.
The system requires high pressure for the membrane to do its job. Typically, for filtering seawater, the pressure needs to be in the range of 600 to 1000 psi.
Although RO systems are used everywhere, even with freshwater, they have become increasingly popular for purifying salt water, especially onboard boats and ships with a direct inline of salt water coming in.
So, most water purifiers for salt water you’ll find on the market are essentially RO systems. However, even within these RO systems, there are a lot of varieties.
Therefore, you need to pay attention to the specifics as to how much water it can filter, what exactly it can remove, and what situation it’s suitable for (home, boats, larger boats, etc.).
Here are some of the best water filters for purifying / desalinating salt water:
If you’re looking to install a salt water filtration system on a boat, look no further than Sea Water Pro. The company specializes in such RO systems, designed exclusively for boats. These are modular water filtration units, which means they are not a single unit, but different components that can be installed anywhere on the boat as space is available.
There are several different systems available in varying sizes, differing by the number of membranes, water flow rate, and voltage.
AC 110-220 Volt, 20 GPH Single Membrane Watermaker
AC 110-220 Volt, 40 GPH Dual Membrane Watermaker
DC 12 Volt, 17 GPH Single Membrane Water Maker
DC 24 Volt, 17 GPH Single Membrane Water Maker
DC 24 Volt, 40 GPH Dual Membrane Water Maker
All SeaWater Pro Watermakers are an efficient, professional salt water purifier, complete with a pump that directly pumps out water from the ocean to make it drinkable.
Sea Water Pro Watermakers provide up to 40 gallons per hour (GPH) and don’t really affect the existing plumbing in the boat.
Whether your sailboat or powerboat has AC or DC current, you can find both options: 110-220 V for AC and 12-24 V for DC.
The maintenance on these systems is pretty much replacing the prefilters and membranes. While prefilters may require replacement in a matter of months, the RO membranes typically have a lifespan of 2 to 4 years.
Furthermore, you can add additional membrane housings to customize the system for your needs, increasing water flow capacity.
Each additional membrane housing is around $600, but this does include a $250 RO membrane as well.
Other than that, the company also offers a UV water sterilizer to use for post purification.
This is ideal for those who want a permanent, long-term water purification solution on their boats and directly utilize seawater.
✔Up to 40 gallons flow per hour
✔Removes salt and other impurities efficiently
✔110-220 v AC and 12-24 V DC availability for both power and sailboats
✔Pressure regulators are made of quality steel
✔Based in Florida, with most parts made in the US
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SeaWater Pro also offer a new portable water maker that combines the same high quality technology, design and durability as their non-portable desalinators. These are perfect for any boat, plus you get to take it with you if you sell or upgrade your current boat.
The portable SeaWater pro makes up to 10 Gallons of purified or desalinated water every hour. It has a brushless motor, is waterproof, and comes with a 2 year warranty.
The high impact and watertight case is easy to carry and has a sturdy pull out handle and wheels for portability and convenience. The system also only weighs 45 LBS (19 Kg) including the lithium battery.
It has various power options. The lithium battery configuration runs for up to 3.5 hours and requires 3 hours to charge. The non-battery plug configuration can connect to 12/24/48 up to 62 volts or to a 110/220 AC generator. You can even run it off a solar panel.
This is a super compact and versatile watermaker perfect for any small-medium sized boat!
✔Compact and portable
✔Runs on various power sources: AC, DC, generator, or solar.
✖Limit of 10 Gal per hour.
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The Katadyn Survivor 06is a portable desalinator, the world’s smallest. This is a compact, lightweight system designed for use in emergencies offshore.
It can be used on smaller and bigger boats alike to desalinate and purify seawater, making it suitable for drinking and ensuring survival.
It has a proprietary seawater membrane that not only removes dissolved salts but also harmful bacteria. This membrane is approved by the FDA too.
It can produce enough water for up to six people in case of emergencies.
Although it can efficiently reduce the salt content of salt water, it’s only viable for emergency use as it works manually and can filter only a limited quantity of water at a time (only 14 ml in a minute).
The whole thing weighs just 2.5 pounds and can easily fit in your backpack or with emergency supplies on the boat.
✔Compact and portable
✔Easy to use
✔FDA approved filter membrane
✔Efficiently desalinates water
✔Good for emergencies
✖Not for regular use
✖Very slow water flow
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The Katadyn PowerSurvivor 40 Eis a high-tech version of the Survivor 06. This machine is capable of desalinating and producing 1.5 GPH. This can support a boat or ship crew of up to three members.
It’s an energy-efficient single-unit system that only requires 12 V. The PowerSurvivor works on the same principles of Reverse Osmosis as other RO systems on this list. However, as it’s designed exclusively for salt water, it combines the right amount of pressure with the right permeability of the RO membrane to remove dissolved salt.
Since it’s very compact, it can work on even very small boats. Also, it can be used as an emergency tool on bigger boats with other primary filtration methods, in case they fail.
✔Compact and portable
✔Three-years components warranty
✔Easy to use
✖Only for three people
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SK Blue Gold Watermakers is a company that specializes in watermakers, i.e., water filters for seawater (salt water). The Blue Gold Watermakers are designed for boats and come in different configurations. These include compact, vertical, standard, and modular.
You can choose the one that fits your needs best. For instance, for a smaller boat, the modular design would be the best choice as it can be installed manually according to the space available.
Some of the features of this system are:
There are two models, the BG-600 and the BG-1500. The former has a flow rate of 25 GPH, while the latter has a flow rate of 62 GPH. Both of the models come with three membranes, however the BG-1500 has bigger size membranes. The voltage requirements are 110/208-230 for both.
The four different configurations make this a flexible system, suitable for a variety of boats. The compact one is better suited for smaller boats and sailboats. Similarly, the modular one is also suitable for smaller boats tight on deck space.
✔Three RO membranes
✔Decent water flow
✔Designed exclusively for boats
✖Not so easy installation
✖Requires electric outlet nearby
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For those looking to turn seawater into drinkable water on a small boat, the EZ-500 Watermaker by SK Blue Gold Watermakers is a perfect choice. It’s a system similar to that of the flagship Blue Gold Watermaker, as it also utilizes Reverse Osmosis to desalinate the water. Through this process, it doesn’t just desalinate, it also removes other micro impurities, common in ocean water.
The EZ-500 offers a flow rate of 20 GPH, which is pretty decent for a small boat. It also features a 12V DC pump to pump out the water from below the boat.
Before reaching the Filmtec membrane, the water goes through a pre-filter with a rating of 5 microns. As a result, it first removes all the sediment particles, which, again, are a nuisance in salt water from the sea.
The system includes a six feet pressure hose that’s enough to place the system away from the source. In other words, you can place the system in a configuration that works for your particular boat.
It does require a pail for flushing the water, which is not included in the system. Also, you need to ensure there’s an electrical switch on the boat, and if there isn’t one (on very small boats), you may have to use a generator.
Thanks to the anti-vibration mounting brakes, the filter stays intact even when the boat hits some rough waters.
You will receive all the specs and user manual for installation, but it’s best to use a professional if you’re unsure.
✔Small scale system that’s space-efficient
✔Decent water flow rate
✔Easy oil change
✖Some parts have to be purchased separately
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SK Blue Gold Watermakers also manufacture large-scale Commercial Desalination Systems that are ideal for offshore vessels, big homes or island resorts. These are big RO systems capable of desalinating and purifying salt water at a high rate.
In this category, there are several models varying by size. They can handle 1,000 to 20,000 gallons per day. The horsepower ranges from 5 to 30. Since these are big, these are permanent installation systems that are not portable.
Such systems can be lifesavers for businesses like resorts and hotels on far-flung islands with no freshwater supplies. Similarly, these can also be used in offshore vessels that require more GPH flow in their plumbing.
✔High flow rates
✔Stainless steel fittings
✔Auto flush tanks
✔TEFC electric motor
✔Made in USA
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The Spectra Catalina 340c Watermaker is designed to desalinate water on midsize boats, like a yacht. It has a flow rate of 14 GPH, which is more than enough for up to five people.
Spectra uses its Magdrive feed pump, which is noiseless and energy-efficient. It provides high pressure for the water feed to pass the RO membrane and for the membrane to do its job effectively.
As a compact modular design system, it’s easy to install it despite the configuration and setup of the deck of the boat or yacht.
You can use it in conjunction with Spectra Connect, which is a remote device that can allow you to control the system and monitor it remotely. It has options like Fill Tank or Auto Run to get things going without doing any manual labor.
With easy one-touch calibration and maintenance monitoring, it makes your life easier, allowing you to change filters timely.
✔Automated system with remote
✔Best for mid-size boats and yachts
✔Designed specifically to filter salt water
✔Reliable water flow with decent pressure
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For boats, the Sea Water Pro RO System is the most viable option as it can be easily installed according to the boat conditions. It can produce ample water to feed the number of people on a small boat or yacht.
For home use, the Waterdrop RO system is the most efficient and doesn’t require a lot of space. In fact, you can even use it on boats or yachts with proper plumbing and a steady water supply from the sea.