Best Fuel Water Separator Filter for Boats – Reviews

Last updated on August 31, 2022

Do you want to get the most power out of your boat’s engine? Do you want to ensure that your engine runs on the purest gas? Are you hoping to avoid the nasty business of engine failures, clogs, and other potentially costly issues?

Then you may want to get your hands on a fuel filter water separator, the sooner the better.

Quick Answer:

The Sierra 18-7982-1 is the best overall water separator currently on the market. With its 99.8% removal rate, high efficiency, and ability to handle up to 90GPH engines this is your best choice. While installation is not the easiest its pros outweigh the slightly longer install process.

  1. Sierra 18-7982-1 Fuel Water Separator Kit - Best Overall
  2. Moeller 033320-10 1 - Best Compact Water Fuel Separator
  3. Moeller Clear Site - Best Moeller Fuel Water Separator with Clear Bowl
  4. Yamaha Outboard MAR-FUELF-IL-TR 10-Micron Fuel Water Separating Filter
  5. Quicksilver Water Separating Fuel Filter - Best Cheap Water Separating Filter
  6. Ebely R12T - Best Universal
  7. KIPA R12T Fuel Filter Water Separator - Best for Diesel Engines

Let’s dive right in.

What’s the Function of the Water Separator in a Fuel System?

In the simplest of terms, a fuel filter water separator is exactly that: a device that separates water from fuel.

Dirty fuel can compromise your entire fuel system. Would you rather be stuck out on the water with an engine that won't run? Or would you spend a couple of bucks on a “just in case” kind of product?

We know what we’d prefer.

How Does a Marine Fuel Filter Water Separator Work?

Now that you know what fuel filters are, you’re probably eager to discover how they work. We don’t want to risk using too much jargon or get too technical so we’ll keep our explanation simple.

In a nutshell: a marine fuel filter water separator removes water, debris, and contaminants from the fuel through a complex filtration & separation system. It does this with the help of filter paper.

Once the undesirables we mentioned above have been separated from the fuel, the clean fuel then runs to the engine and it can perform at its peak.

Best Water Fuel Separators on the Market

1. Sierra 18-7982-1 Fuel Water Separator Kit

Sierra 18-7982-1 Fuel Water Separator Kit

Best Overall

Sierra has been making the lives of boatowners easier for half a century, which is why it should come as no surprise to see one of their products spearheading this list. We’re talking about the 18-7982-1 Separator Kit of course.

Boasting a 99.8% emulsified water removal rate, it’s easy to see why this separator kit is so popular amongst boat owners. The separator’s 10-micron filters operate at a 90% efficiency rate. The Sierra 18-7982-1 Separator Kit flows at 90 GPH so it will be able to meet the needs of even the hungriest motors.


  • Reputable brand
  • 90% efficiency
  • 99.8% emulsified water removal rate


  • Installation can be difficult

2. Moeller 033320-10 10 Micron Water Separating Filter Kit

Moeller 033320-10 10 Micron Water Separating Filter Kit

Best Compact Water Fuel Separator

Does your boat have a Mercury, Johnson, Yamaha, Suzuki, Nissan, Evinrude, Tohatsu or Honda engine? Then consider using the Moeller 033320-10 Water Separating Filter Kit to make the most out of it.

Suitable for both 2 and 4-cycle engines, this water separator kit has 10 microns layers that ensure even the smallest of particles are removed from your fuel. Along with the reusable filter head and filter, all the barbs & plugs you’ll need for installation come with this purchase.


  • Inexpensive
  • Made with powder-coated aluminum
  • For 2 and 4-cycle engines
  • Compatible with many engine types


  • Contents of the filter can’t be viewed without removing the filter entirely
  • May need to replace it more often than other filters

3. Moeller Clear Site Water Separating Fuel Filter System for Outboard Motors

Moeller Clear Site Water Separating Fuel Filter System for outboard Motors (3/8" NPT, Composite)

Best Moeller Fuel Water Separator with Clear Bowl

Another Moeller product has earned its spot on our list; this time it’s their Clear Site Water Separating Fuel Filter System. It’s also known as the 03331410.

The device is comprised of a composite base and a clear plastic bowl which is valuable because you’ll be able to easily view your fuel without the hassle of emptying it. With your filter head comes the necessary barbs and plugs. This unit, the 03331410, has a filter with a 10-micron rating.


  • Able to view contents of the filter with ease
  • Thorough instruction manual included
  • Universal usage for outboard motors


  • Installation can be tricky
  • Included barbs and plugs are ill-fitting

4. Yamaha Outboard MAR-FUELF-IL-TR 10-Micron Fuel Water Separating Filter

Yamaha Outboard MAR-FUELF-IL-TR 10-Micron Fuel Water Separating Filter 90GPH

Best for Yamaha Engines (115 HP or Less)

Why buy an alternative when you can buy a filtration system designed for your boat’s engine by its manufacturer? If you have a Yamaha engine that is rated 115 HP or lower, the Yamaha Outboard MAR-FUELF-IL-TR 10-Micron Fuel Water Separating Filter was designed with you in mind.

This filtration system is able to do what it does thanks to its filtration system of 10 microns and 90 GPH flow rate. The MAR-FUELF-IL-TR Fuel Water Separating Filter needs to be replaced every 50 hours or every six months, whichever comes first. It can only be used for gasoline fuels.


  • Easy to install
  • Incredibly easy to replace
  • Reputable brand


  • Sizing issues are a reoccurring problem
  • Only compatible with Yamaha engines

5. Quicksilver Water Separating Fuel Filter

802893Q01 Fuel/Water Separating Filter Quicksilver/Mercury

Best Cheap Water Separating Filter

Those who like name brands will undoubtedly like this product. While specifically designed for Mercury Marine engines, the Quicksilver Water Separating Fuel Filter can also be used on Mariner and Force outboards as well as MerCruiser sterndrive & inboard engines.

The Quicksilver Water Separating Fuel Filter has a 25-micron filtration system. It is comprised of polyester, cellulose and glass fiber with a silicon-coated phenolic binder. This separator requires yearly replacement, however, if your marine machine is busy during certain seasons you may want to replace it at the start of those periods.


  • Reputable brand
  • Easy to install


  • Flimsy casing
  • Isolated engine fit problems

6. Ebely R12T Fuel Fittings Marine Spin-on Fuel Filter Water Separator

Ebely R12T Fuel Fittings Marine Spin-on Fuel Filter Water Separator 120AT NPT ZG1/4-19 Fit Gasoline Engine and Diesel Engine

Best Universal

If you’ve been looking for a universal fuel filter water separator kit, you can officially end your search. The Ebely R12T Fuel Fittings Marine Spin-on Fuel Filter Water Separator is what you’ve been looking for.

With a flow rate of 30 GPH and a 10-micron filter, your boat—regardless of whether it has a gas or diesel engine—will run better than ever before. It features a clear collection bowl so you don’t have to guess what condition your fuel is in. You also get a self-draining water drain.


  • Clear collection bowl
  • Self-draining feature
  • Compatible with gas and diesel engines
  • Easy to replace


  • Included hose barbs are ill-fitting

7. KIPA R12T Fuel Filter Water Separator

KIPA R12T Fuel Filter Water Separator 120AT NPT ZG1/4-19 with Fitting Complete Combo Filter For Automotive Racor R12T 10 Micron Marine Diesel Engine 3/8 Inch NPT Outboard Motor Durable Spin-on Housing

Best for Diesel Engines

If your watercraft has a diesel engine, using the KIPA R12T Fuel Filter Water Separator is your best bet at making sure it performs optimally. The filter has a 10-micron rating, which is undoubtedly a diesel engine’s dream. It features a reusable clear collection bowl that’s made from high-quality nylon.

Every aspect of the KIPA R12T Fuel Filter Water Separator’s design has been carefully considered from its electrostatically applied corrosion-resistant coating to its self-venting drain. It’s 90% efficient and has a flow rate of 30 GPH.


  • Clear collection bowl
  • Easy to install


  • Included NPT plugs don’t seal properly

Important Buying Information

As with all things related to your vessel, time and effort must be put into purchasing a fuel filter. While inexpensive by nature, the cost of repeatedly buying the incorrect products sure does add up.

Make sure you get your purchase right the first time by taking a look at these important bits of buying information.


Because a water fuel system is such a specific device that serves such a specific purpose, there aren’t many different types available. After all, why fix what isn’t broken? We’ve taken the three most popular variants of this device and laid them out neatly for you to decide which one may be the perfect fit for your boat.

Clear Collection Bowls

As the name suggests, this type of fuel filter water separator features a clear collection bowl near the bottom of the device. These types of filtration systems are usually made from plastic and feature a handy draining vented valve system.


  • A clear bowl allows you to view the fuel and confirm whether it’s clean or if there is debris or emulsified water in it.
  • It’s easy to install. Just be sure to install in it such a position that you can view and drain it easily.


  • Not U.S. Coast Guard approved for usage in enclosed engine compartments (inboards and sterndrives).
  • While installation is easy, achieving the perfect positioning can be a challenge.

Aluminum Bowls

Aluminum bowls are akin to clean collection bowl filters but they feature an aluminum reservoir as opposed to a plastic one. As a result, such systems meet the U.S. Coast Guard’s heat and flame resistance standards. No draining valve is featured in an aluminum bowl’s design but instead, a threaded drain plug can be found on the underside of the device.


  • U.S. Coast Guard-approved.
  • Innovative threaded drain plug draining system.


  • No way of checking the fuel for contaminants aside from emptying it into another container.
  • Difficult to install due to positioning constraints and clearance requirements.

Inspection-free Bowls

Inspection-free bowls are pretty much what you’d expect them to be; systems with bowls that cannot be inspected. These water filters are ideal for outboard installations and engine compartments that have minimal space restrictions.


  • Less expensive than other options.
  • Suitable for usage in most types of engine compartments and conditions.


  • Contents cannot be viewed without completely removing—effectively destroying—the filter and emptying its contents into something else.
  • Requires much more frequent replacement than other options.

Micron Rating

The micron rating refers to the density of the filter paper found within the fuel and water separator. Carburated style marine engines can work with 21-micron filters. For high performance, fuel-injected engines, a micron filter rating of 10 will be most appropriate. Diesel engines typically work well with 2-micron filters.

GPH Rating

The GPH (Gallons per hour) rating of a water separator kit is important. You’ll need to know your boat’s average GPH in order to select a fuel filter water separator that will perform adequately.

Logic dictates that using a fuel filter water separator with a 30 GHP rating on an engine that draws 60 GPH will lead to gas starvation. Applying this same thinking, know that installing a 90 GPH fuel filter water separator on an engine that draws less than this will be nothing short of wasteful.

How Often do they Need to be Changed?

The general rule of thumb for changing your water fuel filtration system is to change it once per year at a minimum. However certain manufacturers, like Yamaha, recommend changing its specific products every six months. So, pay careful attention to what the manufacturer recommends.

Top Brands

As much as we wish all marine accessory brands were created equal, they aren’t. The industry is dominated by the four following brands:

  • Racor 
  • Yamaha
  • Sierra
  • Moeller

How to Install it

Some filters are easy to install while others are a little more difficult but ALL require at least some know-how. Refer to your specific filter’s manufacturers guidelines for exact instructions and turn to helpful “how-to” videos online.

Here’s an overview of the basic step-by-step process of installing such a system on your boat.

  • Step 1: Get your filter and all your tools together.
  • Step 2: Close the fuel valve and open hatches. 
  • Step 3: Plug the line using a bolt. 
  • Step 4: Secure the bolt using a hose clamp. 
  • Step 5: Install the unit’s head between the engine and the tank. 
  • Step 6: Drill the mounting point, or screw it in, and inject sealant of your choice on the threads.
  • Step 7: Fasten the mounting point using stainless steel screws.
  • Step 8: Using the thread sealant, proceed to install the unit’s filter element. 
  • Step 9: Use a small amount of motor oil in the bowl and on the O-rings or gasket. 
  • Step 10: Attach the hose from the tank to the engines in port. 
  • Step 11: Start your boat’s engine and inspect for leaks.


When should I replace my fuel filter water separator?

You should replace your fuel filter water separator kit minimum once per year. If you often take your boat out on the water it’s recommended that you replace it as often as once every six months. Further to these general guidelines, it’s always a good idea to keep a spare (or two!) in case you receive a bad tank of gas.

Can you reuse a fuel filter water separator?

No, a fuel water separator kit is not designed to be reused. Often, as is the case with the KIPA R12T, the bowl may be reused however the device in its entirety is not. Thankfully, they are inexpensive to purchase so this isn’t necessarily a bad thing.

Final Thoughts

Now that you know what to keep in mind when buying a fuel and water separator and have seven stellar options to pick from, are you ready to enjoy a smooth ride?

There’s no doubt about it: at some point or another you’re going to need fuel filter water separator. Save yourself the hassle of an abandoned boat and a long swim back to shore by investing in one today.

About the author  Robert Finn

Robert has over 20 years of experience boating and selling boat equipment. His passion for the latest and greatest gear helps our clients find what they need. His favorite boating place is the Florida Keys.