Reverse Osmosis vs Water Softener Systems

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Looking for a water treatment system for your home’s hard water supply? The obvious choice would be a water softener – but, in some cases, a reverse osmosis system might also be an option.

In this guide, we’ve compared the performance, intended outcome, and design of water softeners vs reverse osmosis systems.

πŸ“Œ Key Takeaways:

  • A water softener is a system that softens water by exchanging magnesium and calcium ions with sodium ions.
  • A reverse osmosis system is a multi-stage filtration system that removes up to 99.9% of total dissolved solids, including dissolved minerals, with a reverse osmosis membrane.
  • Water softeners are primarily intended to soften water, while reverse osmosis filtration systems are designed to purify water.

πŸ†š Reverse Osmosis Vs Water Softener Systems: Overview

Just looking for a quick overview of what makes softeners different from reverse osmosis systems?

Here’s a summary of the key differences between the two:

  • Design. Water softeners have two tanks – one that holds salt for softening, and one that holds the resin bed. Reverse osmosis systems have multiple stages of filtration, including sediment filters, carbon filters, and reverse osmosis membranes.
  • Performance. Water softener systems use ion exchange – the process of exchanging hard minerals with sodium ions – to produce soft water. Reverse osmosis filters use filtration and membrane separation to block most contaminants and produce the purest, bottled water-quality drinking water.
  • Intended result. The purpose of a water softener is to produce softened water. A reverse osmosis system’s purpose is to remove the majority of water contaminants and significantly improve water quality.
Reverse osmosis versus water softener

🚿 What Is A Water Softener?

A water softening system is a two-tank system designed to be installed at water’s point of entry into the home.

This system removes the hard water minerals – calcium and magnesium – from water, eliminating issues including:

  • Limescale on faucets and fixtures
  • Soap scum and poor lathering
  • Dry skin and hair
  • Clogged appliances and reduced water flow

In the water softening process, calcium and magnesium minerals are attracted to the resin bed which, is loaded with sodium ions. When the hardness minerals stick to the resin, the sodium ions are released into the water to balance out its charge.

πŸ‘‰ Check out our reviews of suitable systems.

salt based ion exchange softener

To continue to effectively soften water, a water softener must perform frequent regenerations. In the regeneration process, a softener flushes the resin bed, removing the hardness minerals and replenishing the sodium ions, so the softening process can begin again.

Water softeners come in a variety of sizes, depending on your home’s water pressure and water hardness.

πŸ“Œ Note: there’s also a salt-free softening solution called a water conditioner. Check out our salt-free water conditioner guide to learn more.

salt-free water conditioner

βš—οΈ What Is A Reverse Osmosis System?

A reverse osmosis system is a multi-stage filtration system that’s typically installed as a point-of-use unit (either beneath a kitchen sink or on a kitchen countertop). Some whole house RO systems are now also available.

Reverse osmosis uses a multi-stage water treatment process to remove contaminants and minerals from water, producing pure, bottled water-quality water. The stages of filtration in a conventional RO system are:

  1. A sediment filter
  2. An activated carbon filter
  3. A semipermeable membrane
  4. A carbon post-filter
  5. (Optional) a remineralization filter

In the reverse osmosis process, water flows through these filter stages in succession. The majority of contaminants are removed when water is forced through the semi-permeable membrane at a high pressure. This membrane contains pores so tiny that only pure water molecules can pass through.

Related: What’s the difference between a water softener and a water filter?

A small amount of water containing contaminants is drained at a constant rate throughout the RO filtration process.

Reverse osmosis systems aren’t designed specifically to soften water, but because they remove minerals, they are technically capable of softening and purifying water.

To learn more about all types of reverse osmosis systems click this page.

Tank-Based RO System

πŸ“Š Key Differences Between Water Softeners And Reverse Osmosis Systems

Wondering exactly what makes a water softener vs reverse osmosis system different from one another? We’ve outlined the key differences below.


A conventional water softener has two tanks: a brine tank containing the salt, and a resin tank containing the resin (where the ion exchange process takes place). The unit is controlled by a control head on top of the resin tank.

An RO system has multiple filtration stages and an RO membrane combined in a single unit. Conventional RO filters come with a water storage tank, which stores pressurized water that is delivered to your faucet.

Verdict: Water softening systems and RO systems have very different designs.


A water softener exchanges magnesium and calcium ions with sodium ions to eliminate water hardness.

Reverse osmosis systems use physical filtration and membrane separation to remove almost all impurities from water.

Verdict: Water softening systems use a softening process, while reverse osmosis systems use a filtration process.


A water softener is an efficient system, as long as it has been correctly programmed. Water softening systems do waste some water, however, during regeneration cycles.

Reverse osmosis units are traditionally not very efficient. A conventional RO system wastes 4 gallons of water for every 1 gallon purified. Modern systems are more efficient, wasting only 1 or 2 gallons of water for every 1 gallon purified.

Verdict: RO filters are less efficient than water softening systems.

Reduced amount of water passing through the ro system

Install Location

Water softeners are point-of-entry units, meaning that they’re installed at the main water line upstream of the water heater.

Reverse osmosis systems are most commonly used solely for drinking water treatment, as point-of-use units, meaning that they’re installed under a kitchen sink or on a countertop. Some RO systems are intended for point-of-entry installation.

Verdict: Water softener units are POE systems, while RO units are predominantly POU systems.

Maintenance Requirements

A water softener needs minimal maintenance. Just top up the salt tank every 3 weeks or so and replace the sediment pre-filter every 4-6 months.

Reverse osmosis systems need more frequent maintenance. Each separate filter stage will need to be regularly replaced. Filter lifespan ranges from 6-24 months on average.

Verdict: Water softeners require less maintenance than RO systems.

Pouring iron out in water softener

Intended Result

The goal of water softening is to remove scale-causing minerals and prevent associated problems in the home.

The purpose of an RO system is to remove all tap water impurities, producing water that’s clean and safe to drink.

Verdict: Water softeners soften water, while RO filters purify water.

❇️ Benefits of Water Softeners

The benefits of water softeners include:

  • Don’t need a lot of maintenance – Compared to reverse osmosis systems, a salt-based water softener requires minimal upkeep once you’ve installed it.
  • Provides specific soft water benefits – Water softeners are designed specifically to soften water and reduce scale in your plumbing and appliances, so they’re the best choice if you have very hard water.
  • More efficient – Water softeners are far more efficient than RO systems, so you can benefit from soft water without wasting a large amount of water when the system regenerates.
limescale before after water softener install

❇️ Benefits of Reverse Osmosis Water Filtration

What about the benefits of a reverse osmosis filter?

  • Better-quality water – RO systems don’t only remove magnesium and calcium minerals; they also remove contaminants like chlorine, lead, and bacteria. This improves water quality all around.
  • Protects against pathogens – A reverse osmosis filter can also protect against microbiological contamination, ensuring that drinking water is safe for consumption.
  • Most thorough filtration method – An RO system is the best solution to improve your water quality, removing up to 99.9% of all impurities from drinking water.

πŸ€” Can I Use a Water Softener and RO System Together?

Yes, you can use both a water softener and a reverse osmosis system together – and, in fact, we recommend this if you have hard or very hard water.

High concentrations of hardness minerals will damage and shorten the lifespan of the membrane in a reverse osmosis system, so it’s a good idea to protect the membrane by installing a water softener system upstream of the RO system.

If you have soft or moderately hard water, you should be fine to use an RO system to purify and soften your water concurrently.

Keep Reading: The Perfect Pairing: Reverse Osmosis With Water Softener Systems

πŸ“‘ Final Word

Both water softener and reverse osmosis systems are highly effective water treatment methods – but they don’t produce the same outcome.

If you’re mostly looking to purify your drinking water, install an RO system. But if you mostly want to remove dissolved minerals and eliminate hard water effects, install a water softening system.

Keep in mind the primary purpose of each of these systems. That should help you to decide between a water softener vs reverse osmosis system – or perhaps even pick both.

  • Michael Claybourn
    Water Treatment Specialist

    With 25+ years in water treatment, Michael Claybourn Sr. (WT Specialist 3) leads his company, Water of Texas LLC, in solving industrial, commercial, and residential water challenges. From filtration to ozone, he tackles any task, from initial consultation to equipment maintenance. His passion, honed in nuclear power and Culligan of Brazosport, fuels his commitment to delivering pure, healthy water for every client.

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