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RV Water Softener: What It Is and How It Works

RV Water Softener: What It Is and How It Works

Water is water, right? Well, as it turns out, that’s not necessarily true. Some water, described as “hard”, is filled with minerals like lime and iron, and they can be tough on the skin and on your RV’s plumbing system, even destroying certain appliances. When you’re never sure what your water source will be, either at campgrounds or from water fill stations, being prepared with an RV water softener can be very helpful.

So, today we’re talking about RV water softeners – what they are, how they work, and how they might benefit some RVers.

What is an RV Water Softener?

An RV water softener uses a process called “ion exchange” to soften hard water. Ion exchange replaces hard-water chemicals such as lime, iron, calcium, and magnesium with sodium ions.

limestone can leach high levels of magnesium and calcium into groundwater

In certain regions, high levels of magnesium and calcium can leach from limestone into the groundwater, making the water “hard” and creating a bad taste in the water.

Hard-water chemicals are all capable of accumulating in your RV’s plumbing system, possibly damaging the system and reducing the lifespan of its components. They can accumulate in pipes, fixtures, and your water heater. You may actually have seen evidence of concentrated minerals in your RV showerhead, or in rust staining in your sinks or toilet.

If this is the case, and especially if you spend a lot of time in areas where the water is hard, (such as the Desert Southwest), an RV water softener could help.

How Does an RV Water Softener Work?

If you’ve ever seen an inline water filter like the one we show in this post, an RV water softener works in a similar manner. The water softener connects outside your RV, between the water source and your RV’s water inlet. A form of resin inside the housing acts as an attractant for the unwanted minerals in the incoming water.

As water flows through the softener, ion exchange occurs in the resin… replacing the “hard” minerals (calcium, magnesium, and some iron) with sodium chloride. The resulting output water is now “soft” and continues into your RV’s plumbing system.

When the salt ions in the water softener have been used up in the ion exchange process, the system can be reset using a process called “regeneration” where the resin is re-saturated with the salt ions and flushed of the other minerals it accumulated during use.

Benefits of Using an RV Water Softener

The greatest benefits of using an RV water softener are felt by your skin, your RV’s plumbing system, and your RV’s water-related appliances.

If your RV water heater is damaged by calcification of accumulated minerals from hard water, for example, you could have an expensive repair on your hands – or quite possibly a water heater replacement. The same is true of other RV appliances from washers to coffee makers. Pipes and faucets can also be damaged from the build-up, and the flow of water impacted.

RV water pumps and all other water related appliances can be damaged by hard water.

Hard water can damage RV appliances that use water, including coffee makers, clothes & dishwashers, and even your RV water pump if your fresh water tank is filled with hard water.

Hard water also reduces your soap and other cleaners’ ability to properly foam up. So you may notice that your soap or shower gel doesn’t suds up as much, your dish soap doesn’t seem as foamy, or your laundry may come out looking dingy (and feeling coarse/rough from the minerals left behind).

Moreover, hard water dries out skin and hair, and everyone knows how miserable an issue that can be.

Using a water softener can also improve the taste of your water, and keep mineral deposits in showerheads and faucets, and rust stains in your sinks and toilet bowl, at bay.

How Long Do RV Water Softeners Last?

Portable water softeners themselves are said to last anywhere from 5 to 15 years, but this depends greatly on the hardness of the water being treated, as well as how much water is being used, both of which influence the number of times regeneration occurs.

Some RV water softeners allow for replaceable resin. This means that if the resin needs to be replaced after 5-7 years, new resin can be added that will extend the life of the water softener system for another 5-7 years.

RV water softeners can (and should) be back-flushed every few months for about five minutes to help remove the accumulated “hard” minerals and to keep the system operating effectively. Failing to do so will shorten the lifespan of the water softener. Instructions for the back-flushing process accompany most water softeners.

Is it Okay to Drink Softened Water?

While it’s okay to drink water from a water softener and millions of people drink softened water every day, there are a few things you should know.

An RV water softener is not recommended for people with certain health conditions or for pregnant or nursing mothers.

Regularly drinking water that passes through a water softener is not recommended for folks who are on a low salt diet for health reasons, or for pregnant or nursing women.

Softened water contains slightly more sodium than unsoftened water and is demineralized to a degree. The amount of sodium in the softened water will vary, depending on how “hard” the incoming water supply is. Therefore, if you are on a low-sodium diet for medical reasons, or if you are a pregnant or nursing woman, it’s advisable to consult with your physician.

What to Look For in an RV Water Softener

The first thing you’ll want to consider is the hardness of the water you’ll be softening. That can be tricky for RVers if they move from place to place. A water test kit like this one is useful for determining water hardness – (50 test strips come with this kit, and results are shown in about 30 seconds):

Health Metric Pro Water Hardness Test Kit | Quick & Easy Hard Water Test Strips for Water Softener Dishwasher Well Spa and Pool Water | 50 Tester Strips at 0-425 ppm | Calcium & Magnesium Hardness
  • ✅ EASY TO READ COLOR CHART - From red to green, the large color chart makes distinguishing your test results effortless. The total hardness is...
  • ✅ QUICK AND ACCURATE - Save time and get the test results within seconds. No need to visit a hardware store or wait for someone else to check the...

Typically, when shopping for a water softener, you’d calculate at what capacity you’ll need your water softener to perform. Here’s how that would work:

The level of “hardness” of water is measured in grains per gallon (gpg). The rated capacity of a water softener is the maximum number of grains of water hardness the unit can remove before regeneration must occur.

You’d want to consider the number of people who will be using the water from day to day.

In a house, for example, each person uses an average of 80 gallons per day (YIKES, that seems like a LOT!). In an RV, you should (hopefully!) calculate significantly lower usage than that (for example, when we’re in “extreme boondocking” mode and are trying to extend our fresh water supply, we typically use about 6 gallons of water per day… or about 3 gallons/person per day).

So, you’d multiply the number of people using the water regularly by your calculated daily usage per person, and then multiply that number by the grains of hardness in your water. This would determine how many grains need to be removed daily. You would then purchase an RV water softener that would handle that load.

That would be the technical way to calculate the capacity you’d want to buy.

Most four-person sticks-and-bricks households use a 33,000-grain unit (for an 80-gallon per person average). An RV likely requires a unit of roughly half that capacity.

So, a four-person RVing household would look for around a 16,000-grain unit and a two-person RVing household about half of that.

Leaving the technicalities behind, you might want to consider which units are most popular and most highly rated among RVers.

This 16,000-grain unit is the largest compact RV water softener on the market. It supplies 40% more softened water than any other unit available and takes about 30 minutes to regenerate using two boxes of table salt.

It’s a very popular, highly-rated water softener that uses a standard garden hose connection between the campground’s water source and your RV. It’s also compact, and requires no tools or electricity.

On The Go OTG4-DBLSOFT-Portable 16,000 Grain RV Water Softener (NOT made in China, assembled by U.S. Workers in Indiana)
  • The Double Standard Softener & Conditioner produces twice the gallons compared to the standard model and is the largest compact RV softener on the...
  • Built for the owner of any RV/Marine model, this 16,000 grain unit is a perfect fit and supplies approx. 40% more soft water than any other unit on...

This 8,000-grain unit would be sufficient for a smaller RV with fewer water-related appliances or fewer RVers in the household:

On The Go OTG3NTP3M Portable Water Softener
  • Removes Dirt, Paint, Rust, And Scale
  • Package length: 7.0"

Neither of these units requires frequent regeneration, each uses a box or two of common table salt for the process, and both are reasonable in terms of price and footprint (size and weight).

All of these things are important to consider when shopping for an RV water softener.

What is the Best Alternative to Softening Water?

As an alternative to an RV water softener, you can choose to deal with calcification (if it occurs) by descaling your appliances. For example, you can descale your RV water heater by using white vinegar.

You can also use a product like CLR in appliances like RV washing machines and dishwashers, or to remove scale from shower heads and faucet aerators. (Unfortunately, you can’t descale your RV’s pipes with the same method.)

CLR Calcium, Lime & Rust Remover, Blasts Calcium, Dissolves Lime, Zaps Rust Stains, 28 Ounce Bottle (Packaging May Vary)
  • Industrial Strength: CLR Calcium, Lime and Rust Remover is a non-toxic, multipurpose cleaner designed for bathrooms or kitchen-related surfaces. It...
  • Fast Acting: Quickly removes calcium, lime and hard water deposits, soap scum, discoloration and dirt. Cleans and shines stainless steel, countertops,...

Or, if you’d rather use something less harsh (and/or more readily available), you can use white vinegar as a descaler on your plumbing fixtures and appliances.

Do You Need an RV Water Softener?

The answer to this question really depends on the sources of the water you bring into your RV’s plumbing system, and whether or not you’ve got a problem with “hard” water.

If you tend to be static in – or spend a lot of time in – an area where the water is particularly hard (such as the Desert Southwest, parts of Florida, Wyoming, Montana, Nevada, and others), you may want to consider adding an RV water softener.

However, if you’ve been traveling for some time and your manner of RVing hasn’t raised concerns for you such as mineral build-up in your shower head or sink faucets, or evidence of rust in your sinks or toilets, you may not need a water softener at all.

If you have experienced some or all of these issues, grabbing a test kit to see how hard the water is in the places that you frequent, might be a good idea.

If you’ve been dealing with issues like these, it’s good to know that there may be a solution at hand in an RV water softener.

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Tuesday 16th of November 2021

I use an in-line water filter on my hose, can I add a water softener in-line with the water filter? If so, which should be closer to the faucet, I'm assuming the water softener?


Tuesday 16th of November 2021

Absolutely, Gary. You can certainly add a water softener in-line with an existing water filter. We'd suggest putting the water softener downstream of (after) the inline water filter... that way the water filter will first remove any sediment or particulate contaminants before the water softener does its job.

John Schretlen

Monday 15th of November 2021

This is a good read. I know you have almost perfectly clean soft water at your BC home but Arizona is a different story. Do you have one of these units installed on your rig and, if so, do you use it only when using hard water?


Monday 15th of November 2021

TOO much water in BC these days we hear (we've been seeing the reports of the rain and flooding and mud/rock slides and hoping everyone's staying safe!), but yes... our water in BC is quite wonderful and needs no softening. As we mentioned in our reply to an earlier comment from Mark, we DON'T have one... partly due to lack of storage space (full-timing) and partly because our time in hard water areas in the desert southwest is limited enough (and we don't ALWAYS go south for the winter) that we can get by without one well enough. SHOULD we have & use one when we're down in that area. Yeah... it would make things a lot nicer with the water there. But we just haven't pulled the trigger ourselves... yet. ????


Monday 15th of November 2021

In a normal campground, not boondocking, we use about 20 gallons per day. So we purchased the 8,000 grain unit from On The Go and it works wonderfully.

One suggestion - When you receive the package there is an adapter, female to female, for back flushing. We added quick connects to this unit so we don't have to mess with the hoses when we backflush.


Monday 15th of November 2021

Great idea, Mark! Sounds like that's a really simple, but helpful, upgrade. Thanks for sharing!


Monday 15th of November 2021

So, for all the years you two have been on the road, in your current rig, do you have a water softener?


Monday 15th of November 2021

Hi Mark. We've WANTED one for many years, but haven't made the room (full timing means our basement is pretty chock full) and haven't spent long enough in parts of the world where we need it (desert southwest for us) to pull the trigger. We typically pick up a large, water bottle or two and refill them at the reverse osmosis stations throughout the area. That serves us for drinking water, and we don't find the hard desert water to be TOO much of a problem since we're only there a few months. Soaking the showerhead and faucet aerators in white vinegar is enough to remove the scale from them. And, of course, we use our borescope to inspect our water heater (after flushing it out) and treat it with white vinegar if needed.

Using a water softener would eliminate the need for any of that, of course!

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