RV Water Filters Demystified

Hydro Life HL-170 Under Counter RV Water Filter, held in palm of hand

With the choices today, finding the right RV water filter system is no walk in the park. I’m hoping to make that job a little easier for you by going over water filter types, NSF filter ratings, and canister water filter systems. I’ll also recommend the best water filters for your RV. But first let me tell you my experience with water filters when I started RVing.

After purchasing a second hand 5th wheel travel trailer, I found the water coming out of the faucets smelled and tasted like plastic. So in my infinite wisdom I sanitized the freshwater tank and water lines using chlorine bleach diluted in water. Afterwards I filled my cup for a taste test. It was like drinking from a swimming pool. Now my water had the taste and aroma of plastic and chlorine. Even after flushing the freshwater tank and water lines more times than I care to remember, the unpleasant taste was still there.

Clearly there had to be a way to bring my water up to snuff. I knew the water tasted great before it went into my RV’s water tank. But once that water worked its way to a faucet, there was no way I was going to drink it. So I started looking at under-counter RV water filters. I found the Hydro Life HL-170, which is advertised to reduce chlorine and bad taste, along with several other contaminants.

Installation was easy. I used the included quick connect fittings to install the filter in my cold water line under the kitchen counter. Space was tight, but I made it work. After running the faucet for a few minutes to remove the carbon dust (which must be done with all new carbon filters), I filled my cup…wow, what an improvement! No plastic, no chlorine, no more bad taste. The water was as tasteless as any pure water I’ve tasted, and that’s a good thing!

Soon afterwards I purchased an exterior RV water filter, the TastePure by Camco. I connect this filter to the outside water source, so all water is filtered before it goes into my RV freshwater tank. This protects my tank and entire freshwater system from sediment, bacteria, and other pollutants. Since using this double filtration for my drinking water, I haven’t had a bad cup yet.

Now let’s see what’s behind the magic of water filtration…

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Water Filter Types

The most popular types of RV water filters today include sediment, carbon, KDF, ceramic, and reverse osmosis. All water filters have a micron rating telling you what size particles will be filtered out. 1 micron is equal to one one-thousandth of a millimeter.

Sediment Filters

Sediment filters act like mechanical strainers, catching particles in the water. Sediment can foul up your RV’s water system components, leading to more maintenance down the road. These filters will protect your water pump, water heater, faucets and toilet valves. At the very least, you should use a sediment filter on any water going into your RV.

Carbon Filters

A carbon filter will improve the taste and odor of water, which is something a sediment filter can’t do. Most carbon filters reduce chlorine and bad taste, and many remove other contaminants such as lead, mercury, asbestos, and volatile organic compounds (VOCs).

There are 3 different types of carbon filters..

Filters using granular activated carbon (GAC) are the most common and least expensive carbon filters. Water is passed through fine grains of activated carbon, such as charcoal. These filters are not as effective as solid block carbon and modified carbon block filters due to the reduced surface area of the activated carbon.

It’s best to mount GAC filters in the upright position to minimize “channeling”, a condition where water forms small channels, allowing it to bypass the activated carbon. Water that does not come into contact with the carbon goes through untreated, reducing filter efficiency. Channeling is only a problem with GAC filters.

Solid Block Carbon

Solid block carbon (SBC) filters use pulverized activated carbon that’s been shaped into blocks under high pressure. This technology produces a carbon filter with much more surface area than granular activated carbon can achieve. Channels cannot form and water must come into contact with the activated carbon.

The holes in a carbon block filter are much smaller, giving these filters a higher micron rating. Solid block carbon filters are usually more expensive, but they’re also much more effective than GAC filters and they come with a higher NSF rating.

Modified Carbon Block

The latest and greatest is the modified carbon block (MCB) filter. These filters do everything an SBC filter does, only they last longer and have a better flow rate.


KDF is an alloy with a high level of copper and zinc. It is commonly used in carbon filters because of its bacteriostatic nature, which prevents bacteria from growing inside the filter. KDF also has the benefit of reducing contaminants and heavy metals, and it neutralizes harmful chemicals and metals like lead. Lastly, it removes some of the chlorine in water, helping to prolong the life of activated carbon, which is vulnerable to chlorine. Many carbon filters sold today include KDF.

Ceramic Filters

A ceramic water filter has very small holes enabling it to screen out cryptosporidia cysts, giardia cysts, bacteria, protozoa, and sediment as small as 1 micron. Chemical contaminants are not removed – however, some ceramic water filters do include a carbon component that does remove chemicals. If you’re worried about biological pests in your water, a ceramic RV water filter is the way to go.

Reverse Osmosis

Reverse osmosis is space-age water filtration technology that produces nearly pure water. The secret is a semi-permeable membrane that blocks any particles larger than a water molecule. Unlike carbon filters, reverse osmosis removes nitrates, arsenic, perchlorate, fluoride, and hexavalent chromium. But it cannot remove chlorine, VOCs, or trihalomethanes. So most reverse osmosis systems include a carbon filter too.

A downside with reverse osmosis is that it uses 3 to 20 times more water than it produces. That’s not good news for those who enjoy RV boondocking, where water conservation is critical. The resulting waste water could be reused for watering plants, flushing the toilet, or recycled elsewhere.

Due to the amount of water wasted, you probably wouldn’t want to use reverse osmosis on all the water in your RV. It’s best reserved for drinking and cooking water only.

NSF Ratings

The National Sanitation Foundation (NSF) is a third-party public health and environmental agency that certifies products and issues standards for food, water, and consumer goods. There are several standards established for water filters and these can be found at the link here.

NSF Drinking Water Treatment Standards

Before purchasing an RV water filter, it’s best to check that it meets NSF standards 42 and 53. When reading RV water filter product descriptions, look for something like “Tested and certified by NSF International to NSF/ANSI Standard 42 and Standard 53.”

The standard number tells you what type of contaminants are filtered out. Standard 42 covers chlorine, taste and odor, and particulates. Standard 53 addresses Cryptosporidium, Giardia, lead, volatile organic chemicals (VOCs), and MTBE (methyl tertiary-butyl ether). Standard 58 covers reverse osmosis systems.

Canister Water Filter Systems

Canister water filter systems feature a plastic housing with a water filter cartridge inside. They offer several advantages over one-piece disposable RV water filters. For one, they’re less expensive as all you need to replace is the water filter cartridge, instead of the entire unit. The filters also last longer, provide a better flow rate, and with a standard size canister, you can choose from a wide variety of filters. 

Standard canisters are around 13″ tall x 5″ wide and they accept standard 10″ water filter cartridges. Jumbo canisters are available and these offer a higher flow rate and longer filter life. If you’re experiencing low water pressure with a standard size canister, moving up to a jumbo size may solve the problem. And if you want to go small, there are canisters that accept 5″ tall water filter cartridges. These are great for under-counter RV water filter systems where space is limited.

Culligan RVF-10 External Water Filtraion System

A canister system can be customized however you choose and with any filter cartridges on the market. There are one canister, two canister, and even three canister systems that you can buy, or put together yourself…

Single Canister

With a single canister RV water filter, you’ll have one filter cartridge to perform all your water filtering. A combination filter cartridge that has a sediment and carbon component is a good choice. It won’t be as efficient as a double canister system, but should work fine for occasional RV use.

Double Canister

A double canister system lets you split up filtering tasks, thereby improving filter performance. The most common setup is to put a sediment filter cartridge in the first canister, followed by a carbon filter in the second. This way you remove sediment as well as bad taste and odor.

The sediment filter will typically need to be replaced more often than the carbon filter. Being able to replace one filter type at a time is another advantage of a double canister system.

Triple Canister

If you want an even higher degree of filtration, you could use a system of three canisters. The first could be a sediment filter, next a carbon filter, and lastly a specialized filter. Perhaps a ceramic filter to remove nasty cysts and bacteria.

RV Water Filter Tips

  • Keep a spare water filter cartridge in your RV, should the one you’re using become clogged with sediment.
  • Chlorine will shorten the life of carbon water filters. If you choose to sanitize your freshwater system with chlorine, bypass the RV water filter. You should also bypass the filter when winterizing your travel trailer or motorhome with non-toxic RV anti-freeze.
  • Keep your water free of sediment and tasting great by replacing or cleaning your water filter cartridge at least once a year. Also replace the cartridge if you notice a decreased flow rate in your water lines, which is due to sediment build up.

Choosing the Best RV Water Filter

You have many options when choosing a type of water filter. Here are the most popular variations on the market.

Disposable Exterior RV Water Filters

These filters keep it simple and work great for occasional use. They simply screw into your water hose between the campground faucet. Putting the filter before the hose protects your water hose from contaminants too.

Standard Size Canister Water Filters

These RV water filters use standard 10″ cartridges. Double them up and use a sediment filter cartridge in one canister and a carbon filter in the other for better performance.

Under-Counter RV Water Filters

Water filter installed in water line, in cabinet, below sink
Hydro Life HL-170 under counter water filter, installed in RV water line below sink

Designed for tight spaces, these filters are installed in your cold water line under the kitchen sink.

Jumbo Canister Water Filters

These are designed for whole house water filtration. They have twice the capacity of standard 10″ filters and a much better flow rate.

Reverse Osmosis Systems

Even bottled water may not be as pure as the water from a reverse osmosis system. They do take up more space than an RV water filter, so you’ll have to plan the installation. The good news is the prices are very affordable, especially compared to the high price of bottled water.

Water Filter Lingo

Bacteriostatic – An environment where bacteria cannot grow.
Filter Canister – The water filter housing that holds a filter cartridge.
Filter Cartridge – The replaceable part of the water filter that performs the actual filtering.
GAC – Granular activated carbon. These filters are usually made up of fine grains of charcoal.
GPM – Gallons per minute. Commonly used to measure the flow rate of a water filter.
GPD – Gallons per day. Low flow systems such as reverse osmosis and distillation are often rated in GPD.
Micron – 1 micron equals one one-thousandth of a millimeter. An RV water filter with a rating of 5 microns will filter out particles 5 microns in size and larger.
NSF – National Sanitation Foundation
RO – Reverse osmosis

Bottoms Up

With an RV water filter your H20 can be as clean as a mountain spring. It’s really that easy. Once you’ve installed your water filter, grab a cold one from the tap, then sit back and relax…and have yourself a chuckle at those folks who are still buying water in plastic bottles. Then hand them a cup.


  • Woodall’s RV Owner’s Handbook by Gary Bunzer
  • The RV Water Filter Store
  • Environmental Working Group
  • National Sanitation Foundation

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