RV water filter system

RV Water Treatment System

You need an RV water treatment system. Unless of course, your RV doesn’t have water. Nearly every RV, straight from the factory has an inadequate RV water treatment system.

This article is an update to our 2018 article by the same name. Since then we installed an even better and more robust RV water treatment system. Everything considered in this article about RV water treatment is still valid. The link to our new 2020 RV water treatment system is here. Super-Sized RV Water Treatment System

We have lived with our RV Water Treatment system for a year(2017-2018) and now have better and more consistently good water than we ever had in our house.

“Boy, the water is horrible.”  I don’t remember ever saying that during our first year of RVing full-time. I have low standards; but my wife, on the other hand, has high standards.

The water is horrible

Thus I started my mission to fix the water problem. In 2018 we installed our RV water treatment system. Now we have better and more consistently good water than we ever had in our house. This is the point where I should state that good water doesn’t come cheap, but that is not the case. There were up-front costs but it is not expensive. By the time you read this, we will have covered the entire west half of the country. All cowboy states, and one thing they have in common, almost universally — lousy water.

What makes a good RV Water Treatment system? 

First, good water doesn’t make you sick.  Mostly we rely on the water source to deliver clean, germ-free water to our RV — city water. Germs include bacteria, viruses, fungi, and protozoa. Bacteria are single-cell organism that gets food from their environment. A virus is smaller than bacteria, just DNA and protein. Fungi are plant-like organisms that thrive in a moist environment. Protozoa are single-cell, moisture-loving organisms that are bigger than bacteria. All can make you sick and all are easily killed by chlorine.  We also get water from National Parks and State Parks. We never get water from springs or wells unless we know them to be tested. Perhaps we are naïve, we drink city water. So far we haven’t picked up any water-related illnesses (that we know about).

City water

Cities, almost universally, use chlorine to kill the baddies in the water before we ever put it into our RV.  We appreciate the concern that many folks may have about additives in the water system. But that is not the subject of the article. I do not make any (much) effort to remove the additives in our RV Water Treatment system.

Mostly our concern is particulate matter and water hardness which we address as the water enters the RV.  Put more directly we remove things in the water we don’t want to drink.  The trick is to do it economically.

RV water treatment graphic
Water Path graphic

The factory water system we have in our RV is the most common. Or perhaps not the most common and we just think it is the most common. I have met many people that have similar and not-so-similar systems.   We can use water at city pressure — directly to our faucet. Or we can use city pressure to fill our RV storage tank. (one or the other) Other RVs I have seen lack the ability to use city pressure to fill their storage tank. In our case after filtering, we send the filtered water into the storage tank.  I mention this because my RV water treatment system may not fit your needs.

How to use RV Water Treatment system

Now that I mentioned the design of our RV water treatment system, I want to explain my objectives.  I almost never use city pressure directly to our faucet. I only use the city pressure to fill our tank. After that, I use our water pump to send the water from storage to our faucet.  (I have learned that I am an outlier on this subject and most people do the opposite.)  The reason for my method is simple. I want the freshest water possible in my storage tank as often as possible. By introducing new water, as often as possible the chlorine in the storage tank is renewed.  I want the chlorine in my storage tank and make no attempt to remove it.  Occasionally, I even over-chlorinate, then drain and flush my storage tank. This keeps the storage water germ (and algae) free. Using fresh cleaned and softened water in my storage tank is key to my RV water treatment system.


The filter part of my RV water treatment system is to remove particulate matter (gunk) in my water before it enters my storage tank and this process is simple and inexpensive. I have a two-stage filter (picture) the first stage of the filter strips out the biggest particles down to 5 microns and the second stage filter removes anything bigger than ½-micron that made it through the first filter.  The 5-micron filter I change and replace it with a new filter regularly. The second filter is ceramic and does not need replacement but instead is cleaned with fresh water and a kitchen scrubbing pad and reused.  The ½-micron filter is good enough to remove almost all particulate matter but does nothing to remove suspended minerals in the water.  For this task, I use a water softener.

Stock Photo Water Filter Cask
Stock Photo Water Filter Cask

Chlorine kills the baddies

Before I address the softener, I want to go back to chlorine.  While I want the chlorine in my storage tank I don’t like the taste or smell of chlorine in the water I use, especially the water I drink.  Our RV has a water filter “built-in” between the tank and the faucets. This is where I put a carbon filter so that all the water that goes from the tank to the faucet passes through the carbon. The carbon greatly improves the taste. Since it is being fed particulate-free water, it rarely needs changing and lasts a long time. So to review our RV water treatment system we have three stages of filtering, two for particulate and one for taste and the only filter that gets changed frequently is the first one.

What is soft water?

Soft water, as opposed to hard water, has lower mineral content.  In our travels of the west, I have only found one location that had naturally soft water. The remainder of the water is hard. Calcium and magnesium are the typical minerals that create hard water. They also make the deposits that you find on your showerheads. Removing the minerals isn’t hard or expensive, unlike in a house.  The process to remove the minerals in an RV or house is the same. The difference between an RV and a house is quantity and automation.  In our RV we use only a fraction of the water a house uses so we only have to treat a fraction of the water a house uses. This affects the automation question and the RV water softener in our RV water treatment system has zero automation, lack of automation creates cost savings.

How do you make soft water?

To make soft water, we send the water, as we are filling the tank, through a cartridge full of resin beads.  The minerals in the water, attach themselves to the resin, as the water passes through the cartridge. Minerals gradually build up on the resin in the softener instead of building up on our faucets. Occasionally the minerals need to be removed from the resin.  We know the resin needs to be cleaned because the water makes fewer soap bubbles. We test for hardness using small test papers that change colors when the water contains too many minerals.

Stock Photo Portable Water Softener
Stock Photo Portable Water Softener

How do you “clean” water softener?

To clean the resin (the process is called regeneration) we “flush” the resin tank with a saltwater solution. (One gallon of water combined with one pound of common table salt.) The minerals attach themselves to the salt in the solution and after they are suspended in the saltwater we flush them out.  

Important note:  We do not flush the saltwater into our freshwater storage tank. Instead, we flush directly into the sewer drain. 

I use the filter change as the occasion for regenerating the water softener, using the following sequence:  

  • Remove the hose from the exit of the water softener and connect this hose to the drain.
  • Remove the 5 micron and ½ micron filters from the filter canisters.
  • Remove the top of the water softener then pour salt water into the water softener, then replace the cap.
  • Reattach the filter canisters to the filter housings.
  • Wait for a half-hour for the minerals to transfer from the resin to the saltwater (this step really isn’t necessary but the delay gives me a chance to clean my ½ micron filter).
  • Use the city water pressure, at a slow flow rate, to flush 15 -20 gallons of freshwater through the filter canisters and the softener thus replacing the salt solution with fresh water.   
  • After taste testing for residual salt, reinstall the filters and reattach the water softener exit hose to the storage tank fill hookup.

How to clean your water filter

I have to change my 5-micron filter, wash (sandpaper is involved) my ½-micron filter, and regenerate my resin about every four months — about 2000 gallons

To complete the discussion on water treatment I should mention a few other options that I don’t use. First just as a review I treat all the water I use in the RV with a three-step filter and a one-step softener. I don’t use any of the following methods – but that doesn’t mean that I oppose using any of the following solutions. Another note is that I am not recommending what you should do – instead, I am telling you what I have done.

RV water treatment systems that we don’t use

Reverse Osmosis

Reverse osmosis filters do an excellent job of removing nearly all contaminants in water.  I have at least two friends that use reverse osmosis as their RV water treatment system. They fill their freshwater tank and even shower in reverse osmosis water.  

Filling their freshwater tank takes hours.  Besides being expensive to install, reverse osmosis systems have a huge “cost” in terms of water that is wasted as a byproduct of filtration. For every one gallon of reverse osmosis water created, four gallons of water is wastewater – suitable for watering the landscape, if that was your intent.  If I used creek water to fill my RV storage tank, this is the RV water treatment system I would use. Reverse osmosis is so effective it can strip the salt out of seawater making it an ideal water treatment for a sailboat. On a sailboat, the wastewater is dumped overboard back into the ocean.  Some friends only use reverse osmosis to make drinking water “under the sink” rather than drinking tap water or bottled water.  I just drink tap water – usually after boiling it and combining it with coffee grounds.

Stock Photo Reverse Osmosis Water Filter and Tank
Stock Photo Reverse Osmosis Water Filter and Tank

Ultraviolet light kills germs

I know a few folks who use ultraviolet light to kill germs in their drinking water “under the sink” after filtering it. UV does a great job for people who get their water from suspect origins. Chlorine from the city water supply does the same thing. Using UV light uses lots of electricity but if I didn’t use chlorinated water in my RV I would install a UV light filter in my RV water treatment system.

Stock Photo UV Water Purifier
Stock Photo UV Water Purifier

Silver Nitrate filters (commonly known as KDF) are quite common and have the benefit of killing bacteria. Bacteria die if and when in contact with the silver nitrate. Some of the blue, inline RV water filters found at Wal-Mart are KDF filters.  Even though they are popular, the ones you can buy at Wal-Mart don’t have enough silver nitrate to kill bacteria unless the water sits in the filter for a very long time.

I don’t have enough data to judge this application, but I have used them in the past.  The blue inline RV water filters at Wal-Mart don’t list specifications. I would be surprised if they were five microns. Friends have cut them in half to find all the filtration comes from a sponge found at each end of the filter. The middle of the filter contains carbon that will improve the taste of the water by removing chlorine.  The biggest issue I have with using these is that they have carbon built into the filter. Carbon in a filter removes the chlorine. I want the chlorinated water in my storage tank.

Stock Photo Camco RV Water Filter
Stock Photo Camco RV Water Filter

Some people obsess about the difference between nominal filtration and absolute filtration. The difference is simple and ½ micron “absolute” filter removes ALL particulates greater than ½ micron from the water.  A ½ micron “nominal” filter removes nearly all particulates greater than ½ micron from the water. You can choose which you desire to use in your RV water treatment system. You can guess which is more expensive.

Flow Rate reduces as gunk gets trapped

The flow rate is determined by pressure.  I never have flow problems inside my RV — using my pump for the water source in my RV. My RV water treatment system already filters the water twice before I put it in the RV storage tank. When my fill filters get clogged, (when filling my storage tank) the fill rate drops and I start thinking about changing the filter. However, this is somewhat of a guess because I don’t measure the pressure going into and exiting the filter. Water pressure varies greatly from location to location. I guess I could install my pressure gauge and have a better indication of when I need to change my filters. I haven’t done that. Usually, I change my filters on the basis of the need to regenerate the water softener.

Clogging is good

I have heard complaints that some people don’t want low-micron filters because they clog up frequently. If the filter clogs up, it means that the filter is doing its job. The gunk that caused the clog isn’t in your storage tank. If your filter clogs too quickly it means that you are putting lots of gunk-filled water into your filter. 

Other people obsess about the NSF (National Sanitation Foundation) rating of the carbon filters. NSF class I removes the most chlorine from the water, and NSF class II removes less chlorine from the water. Both greatly improve the taste of the water.  As you can imagine NSF class I filters cost more than NSF class II filters.

Conclusion: We like our RV Water Treatment system, and it does improve the water.  Softness is apparent as is the good taste.  

Remarks: We purchased all of the components for our RV water treatment system and received no compensation for this article.  All the components are available for open purchase. 

Make sure to check the article about our new RV water treatment system in this article. Super-Sized RV Water System

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8 thoughts on “RV Water Treatment System”

  1. Scott, this installation is awesome. Did you do it all yourself? Or I’d like to move my fill system to inside one of my bins instead of on the outside.

        1. to Dave: The key tool is a crimper….. Amazon is $20 and Home Depot is $60. Nippers would do the same thing but requires lots of force. It does take longer to fill the tank through the filters.

    1. to Dennis, I did it (myself) while in North Cascades National Park. We will still need to take some water in for a test, and see if I need to chlorine the system and kill any bad guys I may have collected along the way.

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