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The Best Compact Water Softeners for Tiny Home, Dorm or RV

Fact checked by Stephen Conklin

best compact water softener

Living in a tiny house, cramped apartment, or motorhome is never a hindrance to enjoying the many benefits of soft water. One only needs the best compact water softener to install. The whole family can protect their plumbing and water appliances against limescale buildup, enjoy more pleasant bath times, and make cleanups more efficient.

Compact water softeners work like ordinary water softening units, replacing hard water minerals with sodium ions. Their only difference is the unit’s physical dimensions, making them suitable in small living spaces. That is why many people also call these products space saving water softeners.

We identified three essential factors when picking a compact water softener for the home, apartment, dorm, or RV.

  • Physical Dimensions: Compact water softeners come in different sizes and shapes. Most products have a conventional cylindrical tank, while others come in boxy rectangular shapes. The water softener’s physical dimensions are essential in determining the installation location. The smaller the unit, the better it is for homes with tight spaces.
  • Water Softening Capacity: One obvious drawback of a compact water softener is its capacity. Larger units can accommodate more ion exchange resin, allowing them to soften as much as 64,000 grains of hard minerals between regenerations. Hence, a 16,000-grain portable water softener is better than a 10,000-grain unit.
  • Maintenance Requirements: Water softeners require periodic salt regeneration and resin replacement after several years. Because these appliances are suitable for homes with small spaces, it would be best to get a water softener with minimal maintenance requirements. Maintaining these units can be tedious because of the tiny space they are in.

Other factors can impact one’s decision to buy a compact water softener. We will examine these further in the buying guide section and discuss them in the following product reviews.

Top 1


Dimensions 9.5 x 22 Inches
Weight 35.1 Pounds
Capacity 16,000 Grain

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Top 2

Mobile-Soft-Water MSW0918-M-16S

Dimensions 10 x 21 Inches
Weight 33 Pounds
Capacity 16,000 Grain

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Top 3


Dimensions 15 x 19 Inches
Weight 88 Pounds
Capacity 22, 000 Grain

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Table of Contents

Top 7 Compact Water Softener Reviews

1. On The Go OTG4-VM-DBLSOFT Portable Water Softener

I consider the On The Go OTG4-VM-DBLSOFT the best water softener for small spaces because of its compact design, reliable construction, and noteworthy water softening capability. It is astounding how such a tiny device can protect water appliances and plumbing systems against limescale.

I love this water softener’s tiny footprint, requiring only 9.5 inches of floor space. It stands about 22 inches, allowing it to fit almost anywhere. One can secure this water softener in an apartment, small house, boat, and other tiny living spaces. It also comes with a handle, improving its portability.

This water softener can also be an excellent tool for car wash owners, saving their clients’ vehicles from hard water stains. RVers and travel campers will also love bringing this water softener to their adventures.

Besides its space-saving design, I also like its water softening capacity. It ships preloaded with a high-quality ion exchange resin that accommodates up to 16,000 grains of hard minerals. I find it astonishing, given the water softener’s compact design. Its grain rating is sufficient for a family of four, enabling them to enjoy more pleasant washings without harming their plumbing system.

This mini water softener already comes with brass fittings and other hardware, making installation as hassle-free as possible. Maintaining this water softener is also pain-free because it only requires two boxes of ordinary table salt to recharge the resin. The backflush adapter also allows for effortless maintenance, especially when regenerating the system.

My only comment about this product is its modest flow rate of only three gallons per minute (3 GPM). However, considering its minuscule size, I still think its flow rate is admirable.
  • Space-saving design (9.5 x 22 inches)
  • High water softening capacity, protects against limescale
  • Hassle-free installation with brass fittings and other hardware
  • Portable and versatile design with handle
  • Low salt requirement & backflush adapter for regeneration
  • Modest flow rate at 3 GMP
This compact water softener is one of the best anyone can get. It is perfect for people living in tiny spaces, and its water softening capacity and hassle-free installation are also worth every penny spent on this device.

2. Mobile-Soft-Water MSW 16Kgr Portable Water Softener

People looking for a portable water softener for apartment, tiny house, RV, or boat should consider the Mobile-Soft-Water MSW 16Kgr. This appliance will never demand too much floor space for installation while performing its water softening action.

I love this water softener’s compact design. It only requires a 10-inch diameter floor space and a vertical space of at least 21 inches. One can install the water softener in a motorhome’s under-sink cabinet or bottom compartment. People can also place it against the wall without causing anyone to bump into it.

I am also glad this unit comes preloaded with ½ cubic foot of ion-exchange resin, sufficient for handling 16,000 grains of calcium and magnesium carbonate. I also love its iron removal capabilities, protecting any plumbing system against corrosion and limescale formation.

Surprisingly, this product has one of the highest water flow rates among small home water softener systems, delivering 5 GPM with a water hardness level of 10 grains per gallon (GPG). It might not be as substantial as conventional water softeners. However, it is still astonishing, given its small footprint.

I like the fittings that come with the tank because they adhere to EPA and NSF 61 standards. I know people will appreciate a water softener with certification from reputable quality organizations, giving them confidence in the product.

Although the tank is plastic, I am happy the company reinforced it with fiberglass. The overall design lends the water softener an excellent combination of strength and lightweight characteristics. Moving this product from place to place is never a concern.

On the downside, this softener shouldn’t be used outdoors without a cover.
  • Lightweight and fits in tight spaces (10 x 21 inches)
  • ½ cubic foot resin with high-grain capacity for calcium, magnesium, and iron
  • 16 000-grain capacity
  • Excellent water flow rate (5 GPM) for its size
  • Robust construction with fiberglass-reinforced plastic
  • NSF61 certified and EPA approved water connections
  • Reqiuires covering for outdoor use
Regardless, this water softener remains an excellent product to buy. Small households no longer need to worry about a bulky water softener because this unit fits right into any space.

3. Water Boss 74011 Water Softener

The Water Boss 74011 is an excellent water softener for small families living in apartments, boats, and motorhomes. It has one of the most efficient water softening capabilities among the products I reviewed, making it an exceptional choice for people who want a dependable system to soften their water.

Although the Waterboss water softener is bulkier and heftier than cylindrical compact water softeners, it still has a small footprint compared to traditional water softeners. The tank only needs a 15-inch-wide and 19-inch-deep floor space for installation.

I find the product’s water softening capacity nothing short of splendid. Where other brands can only accommodate 16,000 grains, this product can handle up to 22,000 grains of limescale-producing minerals. A family of four or five can have all the soft water they need without worrying about plumbing repairs and unpleasant water use.

People will also like the water softener’s iron and sediment removal capabilities. According to product documentation, this compact water softener can handle a maximum of 10 ppm iron content. It is good news for households that have high iron concentrations in their water.

Unlike other apartment size water softeners, this product only uses 2.5 to 4 pounds of ordinary table salt to regenerate. Given its 22,000-grain capacity, this salt requirement is surprisingly low. One can only guess it has something to do with the product’s excellent design.

I also like the water softener’s extended warranty – a decade on the media tank and five years for other components, including the electronics.

As mentioned, the only downside is the water softener’s bulkier and heftier physical dimensions compared to other brands.
  • Requires only 15-inch-wide and 19-inch-deep floor space
  • For apartments, boats, and motorhomes
  • High water softening capacity for its size (22,000 grains)
  • Removes hard minerals, iron, and sediments
  • Low regeneration salt requirements (2.5 to 4 pounds)
  • Extended warranty to a decade
  • A bit bulkier and heftier than other compact water softeners
Nevertheless, it is still a compact water softener that behaves like its full-sized cousins – the traditional ion exchange water softeners. With its high-grain capacity, it is one of the best compact water softening systems anyone can buy.

4. On The Go Portable Water Softener

Motorhome owners need not worry about hard water wherever they decide to park their RV ever again. With this portable water softener, a family of two to three can get more effective washings and more pleasant bath times wherever their adventure takes them.

This low profile water softener is one of the smallest I have seen. The tank only reaches a maximum height of 19.5 inches, standing tall on its cradle base. The tank’s diameter is only seven inches, making this water softener among the most compact units anyone can ever use.

Surprisingly, this ultra compact water softener also packs a punch. Not only does it remove 8,000 grains of carbonate from the water, but it also handles dirt, silt, and other sediments. One can look at the device as a multi-purpose system, safeguarding the family’s water appliances and fixtures against clogs, rusts, and limescale formation.

I love the 360-degree swiveling port, allowing for effortless installation. The carry handle also aids in the device’s transportation and correct placement. It does not require special tools to hook up to a public water utility source.

Maintaining the compact water softener is also pain-free. The backflush adapter and shutoff valve help shorten maintenance time to 15 minutes. I also like its low-salt requirements, using only a box of ordinary table salt to keep the system going.

This water softener is perfect for motorhomes. However, ordinary homeowners can also use it if only two to three people are in the household.

I must reiterate this product is not for medium to large-size families. Its 8,000-grain capacity is insufficient to meet the soft water needs of a large household.
  • Super-compact design (119.5 inches tall) with handle
  • Removes sediments, iron, and hard minerals to protect appliances & fixtures
  • Effortless installation with swiveling port & no special tools
  • Has backflush adapter and shutoff valve for 15-minute maintenance
  • For a small household only (8000 grains)
This water softener is a miracle worker for small families. Its portable design is not the only thing outstanding with this product. Its water softening and sediment elimination capabilities are also noteworthy.

5. PRO+AQUA FBA-WS-P-16 Portable RV Water Softener

Many water softener small size units are taller than 20 inches, making them challenging to install in places with limited headroom. The PRO+AQUA FBA-WS-P-16 is not.

This water softener’s 10-inch tank diameter is half the size of its height. Its base is sufficiently wide to give the tank stability. It is also not too tall, lowering the device’s center of gravity and further improving its steadiness on any surface.

Although this water softener for small household is slightly larger than the 7×19.5-inch OTG3NTP3M, it makes up for it by doubling its competitor’s water softening capacity. While the OTG3NTP3M can only accommodate 8,000 grains, this product removes 16,000 grains of carbonates, lead, iron, sediments, rust, silt, and other large particles.

However, it is not the device’s water softening abilities that amazed me, but its thoughtful tank construction. This water softener features polyethylene materials for its inner shell, reinforced with extra-strong fiberglass wrapping. Outside the tank is a neoprene sleeve, protecting the water softener against dents, shocks, vibrations, and other effects of physical forces.

This product’s flow rate is also commendable. People can use five gallons of soft water per minute, making the system an excellent choice for small-shop car wash owners.

Installation is a breeze because of the product’s garden hose connections and a removable control valve head. Maintenance is also pain-free, requiring only two boxes of salt to regenerate within 30 minutes. It is the perfect solution for RVers living in the fast lane.

Unfortunately, these innovations make this water softener pricier than others.
  • Short and stable space-saving design at 10 inches tall)
  • High water softening capacity (16,000 grains)
  • Excellent tank construction and protection
  • High flow rate, suitable for car washing
  • Effortless installation (garden hose connector, removable head)
  • Quick maintenance with two salt boxes
  • Costs more than standard models
I think it is worth it because this water softener does not take up too much space and works as efficiently as conventional water softening systems. I believe this compact water softener offers exceptional value.

6. Watts RV PRO-1000 OR M7002 Portable Water Softener

This slim water softener is almost similar to the PRO+AQUA, except it is taller by two inches. It should fit anywhere in a boat, motorhome, travel trailer, or RV. People living in small apartments and tiny homes can also use this unit to soften their water.

This water softener small spaces model is a compact device that protects plumbing fixtures and water appliances against scale formation while allowing users to appreciate the many benefits of soft water. Never again will families have to worry about scaly faucets, unpleasant showers, and hard water stains on objects.

I love its water flow restrictor technology because it improves the unit’s regeneration. It only requires two pounds of ordinary table salt (about 55% less than other brands) to maintain the ion exchange resin’s water softening capabilities. Other brands need at least four pounds.

This attribute is crucial because the water softener removes 10,000 grains of hard minerals from the water. Other brands only have an 8,000-grain capacity, yet they require more salt to recharge. I can only think of the product’s ingenious ion exchange resin formulation as the reason behind this water softener’s excellent performance.

Hooking up the unit to any water source is also a cinch with its garden hose port. One can use almost any water tubing to run hard water through the cylinder and have it come out as soft water. It helps to know this product also removes trace amounts of iron compounds.
  • Small footprint, can remove iron
  • Recommended for RVs, travel trailers, boats, and more
  • 55% lower salt requirement for regeneration
  • Hassle-free hookups with its garden hose port
  • Higher water softening capacity than other RV water softeners
  • Modest water flow
One thing that might make this water softener unappealing to some people is its 4-GPM flow rate. Despite this, I still recommend this compact water softener to owners of RVs, apartment units, and tiny homes. It works as advertised, is effortless to hook up, and is economical to maintain.

7. Whirlpool WHES30E Whole House Water Softener

To say I like the Whirlpool WHES30E is an understatement. I love it! It reminds me of a GE water softener. Although it is not as compact as the other water softeners in this list, it remains a space-saver among conventional water softening systems.

I adore this water softener because it has an elegant design with powerful water softening capabilities. As an inline water softener, this product is perfect for integrating into one’s existing plumbing system. It can complement other water treatment technologies, such as carbon filters, sediment filters, reverse osmosis systems, and UV treatment systems.

Protecting plumbing fixtures against limescale is never a problem because of this product’s 30,000-grain capacity. A small household can enjoy soft water for several weeks without regenerating it. The good news is that this water softener also removes ferrous iron compounds up to 8 mg/L or 8 ppm.

I also adore this water softener’s automatic regeneration technology, featuring an on-demand system that constantly measures ion exchange resin performance. If the resin performs below its calibrated settings, the system instantly regenerates by calculating the correct amounts of water and salt needed for regeneration.

There are no worries about its performance or quality because it comes with an NSF certification. It reassures people who might be wary of unproven and unreliable products.

As one can expect, this water softener is pricier than most compact units. However, I would not mind paying this much because I know how efficient this water softener is. Furthermore, it feels reassuring that the product is US-engineered, designed, and assembled. Some products have US brands but are sourced from other countries.
  • Ideal for whole-house water softening and can complement other filters
  • Space-saving with high water softening capacity (30,000 grains)
  • Removes hard minerals, including ferrous iron
  • Fully automatic regeneration for cost savings
  • NSF certification. US-engineered, designed, and assembled
  • Not budget-friendly
Overall, this water softener is perfect for small families who want a dependable system for softening their water. Not only does it remove magnesium and calcium, but also ferrous substances to make it an all-around water softener-treatment unit.

What to Look for When Buying Compact Water Softeners


Buying a water softener for small spaces is not that dissimilar from choosing a conventional ion-exchange water softener, differing only in the product’s physical dimensions. Nonetheless, there are several parameters one must consider when buying a compact water softener.

  • Physical Dimensions

In general, compact water softeners have smaller physical dimensions than conventional water softeners. A typical ion-exchange unit weighs more than 80 pounds and measures at least four feet tall and 16 inches in tank diameter, depending on the grain capacity.

A compact water softener will have smaller dimensions. Ideally, it should not be taller than two feet and no wider than 12 inches.

One’s choice of a compact water softener should reflect the available floor space. For example, RVs and motorhomes have less available space than tiny homes and apartments. Hence, one must pick a more compact water softener for RV use than a unit for home or apartment use.

It would be best to determine the location where one intends to install the compact water softener. One must measure the space dimensions to guide in choosing the right water softener size.

  • Water Softening Capacity

After figuring out the water softener’s ideal physical dimensions, the next order of business is to determine how much water softening one needs. Although compact water softeners are a fraction of a conventional water softener’s size, some brands can mimic traditional systems’ water softening performance.

Determining the best small water softener for apartment, RV, boat, or small home use requires calculating water softening requirements.

  • Determine Hard Water Levels

Checking the water’s hard mineral levels is as straightforward as getting a water sample and using a water test kit to check the levels. Unfortunately, test results come in milligrams per liter (mg/L) or parts per million (ppm) values, not grains per gallon (GPG).

Still, it is not an issue because one can convert the mg/L results to GPG values by dividing it by 17.1. For example, a 250 mg/L or 250 ppm water hardness level is equivalent to 14.6 GPG (250 ÷ 17.1 = 14.619). A 100 ppm water hardness level is 5.85 GPG (100 ÷ 17.1 = 5.8479).

Unfortunately, the calculation does not end there. One must also account for the water’s iron content to make the necessary GPG adjustments. As a rule, buyers must add three GPG for every 1 mg/L or 1 ppm of iron. Suppose the water has 10 GPG and 3 ppm iron. In that case, the final water hardness level is 19 GPG (3 ppm x 3 GPG = 9; 9 GPG + 10 GPG = 19 GPG).

  • Determine Average Daily Water Consumption

The next step involves looking at one’s monthly water bill to determine the average daily water consumption. For example, if a family consumes 12,000 gallons monthly, the water consumption is 400 gallons per day (12,000 ÷ 30 = 400).

  • Calculate Water Softening Requirements

Calculating a family’s daily water softening requirement entails multiplying the water hardness level by the average daily water use. Suppose a household consumes 400 gallons of water every day, and the water hardness level is 10 grains per gallon. In that case, the family’s water softening requirement is 4,000 grains per day (400 x 10 = 4000).

One can use the water softening requirement to look for a suitable compact water softener. For instance, an 8,000-grain unit can deliver soft water for two days before requiring regeneration. On the other hand, a 16,000-grain water softener will only require recharging after about four days.

  • Maintenance Requirements

Compact water softeners use salts to recharge the ion exchange resin. That is why it is essential to look at the product’s maintenance requirements before buying.

In general, the lower the device’s water softening capacity, the less salt it needs for regeneration. Some products can recharge using ordinary table salt, while other water softeners might require a specific regeneration product.

It would also be ideal to buy a system with automatic regeneration technology. It monitors resin performance and immediately recharges the unit if the ion exchanger’s performance dips below a preset level.

  • Installation Requirements

Compact water softeners are more straightforward to install than conventional systems. However, some products require professional installation because of their complicated setups. It would be best to check the water softener’s setup requirements before buying.

One must also check the hardware included in the package. It does not make sense to buy an expensive product that has incomplete or no installation hardware. Having an installation manual or CD can also aid in the water softener’s successful setup.

  • Overall Construction

Traditional water softeners have reinforced steel tanks, making them sturdy yet heavy. On the other hand, compact water softeners use lighter materials to improve their portability.

Most products use fiberglass-reinforced plastic tanks. Some brands wrap their water softeners in neoprene sleeves, protecting them against vibrations and impact forces.

  • Quality Assurance

While not absolute, a water softener with a third-party quality certification is better than one without. Ideally, the assurance must come from the Environmental Protection Agency (EPA), National Sanitation Foundation (NSF), Water Quality Association (WQA), or other reputable quality standards organizations.

  • Warranty

One way to gauge a water softener’s quality construction and performance is its warranty. Companies that believe in their products’ quality provide extended guarantees for as long as ten years. Unfortunately, some brands only cover their water softeners for 12 to 24 months.

  • Price

Just because a compact water softener is small does not automatically translate to affordability. While it is more affordable than conventional water softeners, a compact unit can still command a high price if it comes with advanced technologies, high water softening capacity, and other features not found in other products.

What Is the Smallest Size Water Softener


The smallest water softener in this list is the On The Go OTG3NTP3M, with a 7-inch-diameter, 19.5-inch tall tank. The On The Go OTG4-VM-DBLSOFT has a similar diameter but is taller by 2.5 inches and wider by more than 2 inches.

The PRO+AQUA is also small at only 20 by 10 inches. Its principal advantage over the OTG3NTP3M is its higher water softening capacity (16,000 grains vs. 8,000 grains), making the PRO+AQUA a better choice.

The Mobile-Soft-Water and Watts RV PRO-1000 are not far behind at 10×21 inches and 10×22 inches, respectively.

People who want a non-cylindrical water softener can choose the Water Boss 74011 because it only measures 15 inches wide, 19 inches deep, and 26 inches high. The good thing about this product is that it has the second-highest water softening capacity among the products reviewed, next only to Whirlpool’s 30,000-grain capacity unit.

Can You Use a Compact Water Softener in RV

Yes, you can use compact water softener systems in marine vessels, motorhomes, travel trailers, and RVs. However, it would be best to measure the space for water softener installation. Doing so helps determine the most appropriate size water softener.

Of the seven compact water softeners reviewed, the On The Go OTG3NTP3M water softener fits the bill perfectly because of its petite physicality (7-inch diameter, 19.5-inch tall). The PRO+AQUA is a close second with its 10-inch diameter, 20-inch tall dimensions.

These products also have garden hose ports for effortless hookups to any water source.

How Much Salt Does a Compact Water Softener Consume

A water softener’s salt requirements for regeneration depend on its water softening capacity. For example, a 24,000-grain unit might require 27 pounds of salt for recharging the system. On the other hand, a 36,000-grain water softener will need about 36 pounds of salt for regeneration.

Small water softener systems can use anywhere between eight and eighteen pounds of salt to regenerate. Some manufacturers can use less, others more.

Some manufacturers use an upflow technology to minimize salt consumption. For example, a conventional water softener might need 20 pounds of salt. A water softener with an upflow technology can reduce the salt requirements by 30 percent, prompting the owner to use only 14 pounds of salt for regeneration.

Unfortunately, many water softener manufacturers do not put their products’ salt requirements in their marketing materials. One must research the water softener’s actual salt consumption before buying. If one cannot find the information, he can estimate the salt requirements by dividing the water softener’s grain rating by 888.8889.

For example, a 16,000-grain compact water softener might require 18 pounds of salt (16,000 grains ÷ 888.8889 = 17.999999775).

How Many People Can Depend on a Compact Water Softener

The number of people using a compact water softener depends on the appliance’s water softening capacity and the water hardness level.

One must determine the water hardness level in their home using a water test kit, then use this information to determine how many people an apartment size water softener can accommodate.

Suppose the water softener can handle 8,000 grains before recharging and the water hardness level is 12 GPG. In that case, it would be safe to assume that the unit can deliver 666 to 667 gallons of soft water before regeneration (8,000 ÷ 12 = 666.66667).

If one person consumes 70 gallons of soft water every day, the 8,000-grain unit will provide soft water for nine to ten days (666 ÷ 70 = 9.5). If there are three people in the household, the device might only provide soft water for three days.

In general, compact water softeners are ideal for a four-member household or less.


The best compact water softener is perfect for small families and RV owners. The device’s small footprint fits into the tightest spaces without undermining its water softening capabilities. People can enjoy the many advantages of conventional water softeners without giving up precious floor space and shelling out handsome amounts of money.

Picking the right compact water softener for the home or RV entails understanding one’s water softening needs, installation and maintenance requirements, and a few other parameters. If one wants to narrow down his choices, our review of the market’s top-rated compact water softeners is an excellent starting point.

5/5 - (2 votes)