I’ll never forget the look on a customer’s face when he brought his Class A into a service shop in Florida and the technician showed him the inside of his water heater tank. Two years of hard water had deposited a thick layer of calcium and mineral scale on the heating element and the tank walls. The element was working twice as hard to heat the water, burning through propane at an alarming rate, and the tank was losing capacity due to the buildup. The repair bill was over $400, and it was entirely preventable with a $150 water softener.
Hard water is one of those invisible problems in the RV world. You can’t see it, you can’t smell it (usually), and the damage happens so gradually that most RV owners don’t notice until something fails. But the minerals in hard water—primarily calcium and magnesium—are silently coating the inside of your water heater, your plumbing lines, your faucet aerators, and your showerhead every time you hook up at a campground with hard water. And hard water is common across large portions of the United States, particularly in the Southwest, Midwest, and Florida.
Water softeners remove those minerals before they enter your RV’s plumbing system. De-ionizing filters go a step further, removing virtually all dissolved minerals and producing spot-free water that’s also ideal for washing your RV’s exterior without leaving water spots. This roundup covers the best portable water treatment systems we carry at the RV Upgrade Store.
Best for: RV owners who want spot-free wash water and the purest possible water for their plumbing system
De-ionized water is what you get when you remove all dissolved minerals from the water supply. Unlike softened water, which replaces calcium and magnesium with sodium, de-ionized water contains virtually no dissolved solids at all. The practical benefit for RV owners is twofold: inside your rig, it eliminates scale buildup entirely. Outside, it produces spot-free rinse water that dries clean without leaving mineral deposits on your paint, glass, or gelcoat.
The On The Go mixed bed deionizer is a portable unit that connects inline between the campground water supply and your RV’s water inlet. The mixed bed resin inside the tank exchanges hydrogen and hydroxide ions for the dissolved minerals in the water, producing water that’s cleaner than what most people drink at home. It’s the same technology used in laboratories, car washes, and commercial cleaning operations, scaled down to a size that works for RV use.
I recommend de-ionizers particularly for RV owners who are fastidious about the exterior appearance of their rig. Anyone who’s spent an afternoon washing a dark-colored motorhome only to have water spots appear as it dries knows the frustration. De-ionized water eliminates that problem completely. Wash, rinse, and walk away—the water dries clear without any spotting.
The resin in the deionizer does need to be replaced periodically as it becomes exhausted. How often depends on the hardness of the water you’re treating and how much water you use. In areas with very hard water, the resin may last a few hundred gallons. In areas with moderate water, you might get several thousand gallons before replacement is needed. A simple TDS (total dissolved solids) meter will tell you when the resin is no longer doing its job.
Pro Tip: Use a TDS meter to test the output water regularly. Fresh resin produces water with 0–2 ppm TDS. When the reading starts climbing above 10–15 ppm, the resin is approaching exhaustion and should be replaced for optimal results.
Buy the On The Go Water Deionizer
Best for: Premium water treatment with longer resin life and more durable construction
The dual bed version of On The Go’s deionizer system takes the concept a step further with a two-stage filtration design. Instead of a single mixed bed of resin, the dual bed system separates the cation and anion exchange resins into two stages. The practical advantage is longer resin life and more efficient mineral removal, especially in areas with particularly hard water.
The brass fittings are a meaningful upgrade over the plastic fittings found on less expensive models. Brass doesn’t crack in cold weather, doesn’t strip when you over-tighten it, and doesn’t develop the pinhole leaks that plague plastic fittings after years of UV exposure and repeated connection cycles. For a piece of equipment that lives outside and gets connected and disconnected regularly, brass fittings are worth the premium.
This is the model I recommend for RV owners who spend extended time in hard water areas—the Southwest, parts of Texas, Florida, and the Great Plains states. If you’re a full-timer or extended traveler passing through these regions regularly, the dual bed design extends your resin life significantly, reducing the frequency and cost of replacements over the long term.
The overall build quality is a step above the standard model, with a more robust tank and better pressure handling. If you’re investing in a water treatment system for the long haul rather than trying it out to see if you like it, this is the model to buy.
Pro Tip: When storing your deionizer between trips, keep the resin wet. Dry resin loses its exchange capacity and won’t rehydrate to full effectiveness. Cap both ends with the provided plugs and store it in an upright position with some water inside.
Buy the On The Go Dual Bed Deionizer
Best for: Protecting your RV’s plumbing and water heater from hard water damage
If your primary concern is protecting your RV’s internal plumbing rather than producing spot-free wash water, a traditional water softener is the more practical choice. Water softeners use an ion exchange process to replace the calcium and magnesium in hard water with sodium, which doesn’t form scale deposits in your plumbing, water heater, or fixtures.
The On The Go portable water softener is the most popular RV water softener on the market, and it’s earned that position through years of reliable service. The compact design fits in a basement compartment or beside your RV’s water hookup, and it connects inline with a standard garden hose. Water flows through the softening resin before entering your RV, and you’ll notice the difference immediately—soap lathers better, dishes come out cleaner, and your skin and hair feel softer after a shower.
The key advantage of a softener over a deionizer is regeneration. When the softening resin becomes exhausted, you don’t replace it—you regenerate it by flushing it with ordinary table salt. A simple regeneration takes about 30 minutes and uses a couple of pounds of salt, restoring the resin to full effectiveness. Over the life of the unit, this is dramatically cheaper than replacing deionizer resin cartridges.
The tradeoff is that softened water isn’t spot-free—it still contains sodium and other dissolved solids. For interior plumbing protection and daily use, that’s perfectly fine. If you also want spot-free wash water, you can run a deionizer after the softener for exterior washing only.
Pro Tip: Regenerate your water softener before each trip, not after. Fresh resin gives you maximum protection from the start. Keep a bag of table salt in your RV’s storage—it’s cheap, lasts indefinitely, and means you can regenerate anywhere without hunting for a store.
Buy the On The Go Water Softener
Best for: Budget-conscious RV owners who want basic hard water protection at a lower price point
The FlowPur RV Pro 10,000 offers the core benefits of water softening—scale prevention, better soap performance, and plumbing protection—at a price point that makes it accessible to RV owners who aren’t ready to invest in a premium system. The “10,000” in the name refers to the grain capacity, which indicates how much hardness the resin can remove before it needs regeneration.
The 10,000-grain capacity is adequate for weekend and short-trip RV use in moderately hard water areas. Full-timers in very hard water areas will find themselves regenerating more frequently, which is where a larger unit like the On The Go becomes more practical. But for seasonal RVers who primarily camp in regions with moderate water quality, the FlowPur does the job at a fraction of the cost.
Like the On The Go, the FlowPur regenerates with table salt—no special chemicals, no expensive cartridges, no professional service required. The regeneration process is straightforward and the instructions are clear. Connect a garden hose, add salt, run water through the unit for about 30 minutes, and the resin is ready for another round of service.
Build quality is basic but functional. The tank is smaller and lighter than the On The Go, which some owners actually prefer because it’s easier to handle and store. The fittings are standard garden hose connections. It’s not going to win any beauty contests, but it protects your plumbing, extends the life of your water heater, and makes your shower feel noticeably better. For the price, it’s hard to argue with.
Pro Tip: Check the hardness of the water at your campground before deciding how aggressively to use your softener. Many campgrounds have water quality reports posted at the office. If the hardness is below 3 grains per gallon, you may not need the softener at all for that stop. Save the resin capacity for the campgrounds where you really need it.
Buy the FlowPur Water Softener
The choice between a water softener and a de-ionizer depends on what problem you’re trying to solve. If your main goal is protecting your RV’s plumbing, water heater, and fixtures from scale buildup, a water softener is the right choice. It’s cheaper to maintain (salt vs replacement resin), produces water that’s perfectly fine for drinking, cooking, and bathing, and handles the high flow rates of daily RV water use efficiently.
If your primary concern is spot-free washing for your RV’s exterior—or if you want the absolute purest water for your plumbing system—a de-ionizer is the answer. De-ionized water leaves zero mineral residue on any surface, which makes exterior washing a breeze. The tradeoff is a higher ongoing cost (replacement resin vs cheap salt) and lower flow rates that make de-ionizers less practical as your primary water supply for all daily use.
The ideal setup for serious RV owners combines both: a water softener inline for daily water use, protecting your plumbing and improving your shower, with a de-ionizer available for exterior washing and final rinses. This dual approach gives you the best of both worlds without overworking either system.
Hard water damage is entirely preventable, and the prevention costs a fraction of the repair. A portable water softener or de-ionizer pays for itself the first time it saves you a water heater replacement, a faucet rebuild, or an afternoon of buffing water spots off your coach.
Every system in this roundup is designed for portable RV use—compact enough to store in a compartment, simple enough to connect and disconnect at each campground, and effective enough to make a real difference in your water quality. Start with the system that matches your primary concern and budget, and upgrade from there as you experience the benefits. Once you’ve used treated water in your RV, going back to raw campground water feels like a compromise you’re no longer willing to make.
I’m Bill Rowell, the founder of RVupgrades.com. In 2002, I launched the business to help fellow RV enthusiasts find unique and hard-to-find products. Over the years, it’s grown to offer more than 15,000 items, with a warehouse in Eastlake, Ohio. Having owned and repaired nearly every type of RV, I bring over two decades of hands-on experience to the table. For me, this isn’t just a business – it’s a passion and a way of life that I love sharing with the RV community.
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