Best Water Filter for Sailboats: Marine Systems

Saltwater vs. Freshwater Filtration Systems

The type of filter you need depends a lot on the type of water you need to filter. For freshwater filtering (such as from a lake or onboard freshwater tank), a standalone inline filter will suffice. Special filters should be used if you intend to drink lake water, and some people recommend reverse osmosis for all water sources.

Reverse osmosis filter systems are required for filtering salt water into drinkable water. The process itself is called desalination, and reverse osmosis systems can do it effectively. Another way to convert saltwater into drinkable freshwater is through distillation, but this process only works efficiently at scale, and it's impractical for personal sailboats.

What is Reverse Osmosis?

Reverse osmosis is the most effective small marine water filtration system available today. Reverse osmosis (RO) systems are compact and energy-efficient, and they have become quite affordable.

Reverse osmosis is essentially a pressurized filtration system with an extremely fine filter. The process forces dirty water to pass through a membrane which traps all particles (including salt) that aren't pure water. These systems are just as effective with saltwater as they are with fresh water, though they'll need to be cleaned more often when used in the ocean.

Should I Buy a Reverse Osmosis Filter for my Freshwater Boat?

You don't need a reverse osmosis system to make freshwater drinkable. Charcoal filters will usually do the trick, and many people are satisfied with them. Freshwater filters don't always require electricity, whereas reverse osmosis systems always require some source of power to produce the necessary pressure.

That said, reverse osmosis systems can produce large volumes of highly purified water, and they do a better job when combined with charcoal filters than charcoal systems alone. Additionally, reverse osmosis filters are the only kind of marine filters that can desalinate water on a small scale.

Best Reverse Osmosis Boat Water Filters

Reverse osmosis filters are the best water purifiers available for boats. These systems purify freshwater and desalinate saltwater, making them ideal for all environments. Here are three of the highest-rated RO filter systems on the market.

1. Seawater Pro Reverse Osmosis Desalinator and Watermaker

The best modular water filtration unit available for boats is the Seawater Pro three-membrane system. This all-in-one marine water purification machine is designed for medium-sized sailboats and powerboats.

This Seawater Pro system is a professional-level filtration plant that produces up to 50 gallons of clean drinkable water per hour directly from the ocean. It's designed to be installed in-line with existing plumbing, and it requires electricity to run.

Seawater Pro watermaker and desalination systems are available in 110v AC or 12v DC configurations, which means any boat with sufficient power can utilize one of these systems. Seawater Pro systems come in different sizes and configurations, and many can run off a standard 1600-watt electric generator.

If you're looking for a long-term watermarking solution for your boat, you can't go wrong with Seawater Pro. The system is compact and reliable, and owners are highly satisfied with the quality of water they're getting.

Key Features

50 gallons per hour
80 gallon-per-hour systems available
110v AC or 12v DC models available
Stainless steel pressure regulators
Food-grade pressure vessel
Many parts are Made in the USA with a lifetime warranty

2. SeaXchange Watermaker XTC Series

SeaXchange produces one of the best self-contained marine water filtration systems on the market today. The SeaXchange III XTC series is their flagship watermaker and filter for boats, and it's available in multiple sizes.

For smaller boats, the SeaXchange XTC600 is ideal. It has a single membrane that can purify up to 25 gallons of water per hour. Larger boats can utilize the XTC200, which has an hourly purification capacity of 92 gallons.

The SeaXchange XTC is a reverse osmosis watermaker that functions much like the Seawater Pro unit. This system purifies water and desalinates saltwater using pressure and an ultrafine membrane.

The SeaXchange XTC series is modular, which means it includes all of the specialized components you need to convert seawater into drinkable fresh water; though professional installation is recommended, the modular design of this unit means you can get it up and running quickly without ordering any additional proprietary parts.

Key Features

Units available that produce between 25 and 92 gallons of fresh water per hour
It's the only marine reverse osmosis system with mechanical redundancy
70 electronic control display
Smartphone-compatible controls
One-touch operation and automated controls

3. Pentair Pelican Six-Stage Filtration System

The Pentair Pelican is the most compact reverse-osmosis water filtration system on our list. And while it might not be the best option for desalination, it can easily purify freshwater from your tanks for drinking.

The Pelican six-stage water filter system is designed for as-needed water consumption, and it hooks up directly to a faucet. This unit uses a six-stage process to remove dissolved substances, sediment, foul tastes, and toxic chemicals. It also removes harmful contaminants such as parasites.

The process starts with reverse osmosis, which does the majority of the actual purifying. Next, water passes through a pre-filter, then to the specialized filter itself. After, water makes its way through an additional membrane to remove any remaining contaminants. The final steps in the process are polishing and mineral re-introduction for improved taste and health benefits.

The unit itself is designed for home use, but it can work just as well in the galley of a sailboat provided the pressure and power requirements are met. The Pelican Six-Stage reverse osmosis system is the most affordable of its kind on our list.

Key Features

17.9 Gallons per day
40 to 80 PSI operating pressure
Designed for use with a single faucet
Reverse osmosis and filter combination
Made in the USA
6 to 18-month filter life

Best Standard Filtration Systems for Boats

Now, let's move on to standard filtration systems. Standard filters don't desalinate, but they're much simpler and more affordable than reverse-osmosis systems.

Most marine water filters utilize activated charcoal as the primary purification medium. Activated charcoal removes chemical contaminants, foul smells, bad tastes, and most pathogens. This method of filtration is usually backed up by additional filters which remove larger particles such as tank sediment, plant matter, and dirt.

Many of these marine filtration systems are passive and use existing water pressure to operate. That means that they don't require any additional power, assuming the water is either pre-pressurized or drawn up from the tank with a hand-pumped spigot.

1. Aquasana Three-Stage Water Filter

The Aquasana Three-Stage water filtration system purifies freshwater using a unique combination of large particle and charcoal filters. The company claims that this compact filter system "reduces 15X more contaminants than the leading pitcher filter..." Also, the Aquasana system is passive and requires no additional power.

Aquasana's three-stage Claryum system relies on three separate inline filter canisters, which are easy to replace. Simply twist off the canisters, remove the cylindrical filters, and replace them. The filters have a combined service life of 600 gallons, though the company recommends replacing them every six months.

The first stage in the process is a large particle pre-filter. This filter removes dirt, rust, and other sediments that would cause your water to look murky. The second and third filters contain various kinds of charcoal, which are responsible for most of the true purification. A combination of activated charcoal, catalytic carbon, and ion-exchange material remove 99% of lead, 96% of PFOS/PFOA, pathogens, and 75 more harmful substances.

This filter has a relatively low 5 gallon per minute flow rate, though it's sufficient for most galley faucets. The kit comes complete with a faucet as well, which is available in three colors.

Key Features

Passive three-stage freshwater filter
Meets NSF/ANSI standards 42, 53, and 401
Six-month/600-gallon filter life
40-80 PSI operating range

2. West Marine HighFlo KDF Water Filter

West Marine offers an excellent water filter that's designed specifically for boats. The West Marine HighFlo filtration system is a compact single-canister freshwater filter designed to be an inline addition to your existing plumbing.

Over time, freshwater tanks on boats accumulate grime and sediment. Worse yet, boat tanks can harbor pathogens and leach toxic chemicals into your drinking water. Not to mention the fact that, more often than not, marina water isn't the cleanest or best-tasting either.

The West Marine HighFlo KDF filter mitigates these issues without any additional electricity. This-filter has a capacity of five gallons 5 gallons per minute, which is about twice the flow rate of many similar products. The filter contains activated charcoal, which traps bacteria, dirt, and toxins such as lead and chromium.

The filter itself is easy to install and maintain, as filter replacements should only occur seasonally. The filter itself also removes chlorine, which could be leftover from tank cleaning. This filter is highly affordable, and replacement filters are readily available through West Marine,

Key Features

2.5 to 5 GPM flow rate
The charcoal filter removes particles 5 microns and larger
One-season filter lifespan
Non-electric
Inline installation

3. Aquabrick Portable Water Filtration System

The Aquabrick water filtration system is an excellent option for small boats based on freshwater. This system is designed for survival use, but it can also serve as a water storage and purification system for your boat. It’s compact and pressurized, allowing you to enjoy strong water flow. With a bit of engineering, you can connect it directly to a faucet in your boat.

The Aquabrick consists of a tank, a hand pump, a filter, and a spigot attached to a line. By pressurizing the tank with the hand pump, you force water through the DuraFlow filter and into the spigot on the end of the line. The tank itself stores three gallons of water, and the filter is good for up to 700 gallons overall.

According to the manufacturer, the Aquabrick DuraFlow filter “removes 99.99999% of all bacteria…” along with 99.99% of viruses. Additionally, the filter removes chemicals such as chlorine and heavy metals such as lead and chromium. That means that virtually any lake or river water will be safe to drink and cook with after passing through the filter.