Does Reverse Osmosis Soften Water?

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Reverse osmosis systems are considered the crΓ¨me de la crΓ¨me of all water filters, thanks to their ability to virtually purify drinking water – but does this purification process produce soft water?

In this guide, we’ve answered the common question: “Can a reverse osmosis system soften water?”

πŸ“Œ Key Takeaways:

  • A reverse osmosis system can produce soft water, but excess hard water scale will damage the membrane and shorten its lifespan.
  • The best method of water softening is ion exchange, used in a conventional whole-home water softener system.
  • Installing a water softener upstream of an RO system will protect the semi-permeable membrane and support its long-term performance.

πŸ“‘ Do Reverse Osmosis Systems Soften Water? Quick Answer

Yes, a reverse osmosis system does soften water because it removes all impurities from water, including the calcium and magnesium minerals that are responsible for hard water.

However, if you have hard water and your main goal is water softening, we don’t recommend using a reverse osmosis system solely for this purpose.

High levels of mineral hardness will build up on the surface of the RO membrane, preventing water from passing through and restricting its efficiency.

A reverse osmosis water filter wastes water steadily during the RO process. When contaminants rebound off the membrane, they’re sent down a drain with a small amount of wastewater.

If the membrane is clogged with scale and the water particles can’t easily pass through, they’ll end up rebounding, too, resulting in more water waste.

Scale buildup will eventually clog, damage, and degrade the RO membrane to the point that it needs to be replaced early. That means your maintenance costs will be higher, since the average lifespan of a reverse osmosis membrane is 2 years.

We only recommend using a reverse osmosis system for soft water treatment if your calcium hardness is mild or moderate. If you have hard or very hard water, use a water softener as your main port of call for softening.

Reverse osmosis water in a glass on a table

πŸ†š Water Softeners vs Reverse Osmosis Systems: Key Differences

The main difference between water softening systems and reverse osmosis water filtration systems is that water softeners soften water, while reverse osmosis systems filter water.

Let’s look in more detail at the differences in performance between these two water treatment solutions.

A water softener is installed at your main water line and uses a process called ion exchange, which exchanges magnesium and calcium ions (which are responsible for hard water scale) with sodium or salt ions.

Sodium is a good alternative to calcium and magnesium in water because it doesn’t have scale-forming effects. Exchanging hardness minerals with sodium ions is an effective way to prevent hard water issues, including soap scum, scale on your plumbing fixtures, and dry skin and hair.

Because water softeners are installed at your home’s point of entry, upstream of your water heater, they provide softening benefits throughout your entire home’s hot and cold water plumbing system.

A reverse osmosis (or RO) system is typically installed as a point-of-use system (such as under-sink or countertop) and filters water. This water treatment system uses a process called membrane separation to remove contaminants from water.

When water travels through the reverse osmosis membrane, the membrane pores are so small that only water particles can pass through. Reverse osmosis removes all total dissolved solids (TDS), including chemicals, dissolved minerals, salts, metals, and even many microorganisms. The end result is purified water that’s clean and safe to drink.

Most commonly, RO systems are used for tap water treatment. However, there are a few reverse osmosis units that are designed for installation at your home’s point of entry, providing RO filtered water to your whole home.

Related: Is Reverse Osmosis Water Hard or Soft?

Reverse osmosis versus water softener systems

βœ… Benefits of Using Reverse Osmosis & Water Softeners Together

What if you want soft water and pure water? Rather than leaving an RO system to do all the heavy lifting, we recommend installing both a water softener and a reverse osmosis filter in your home.

Some of the benefits of a water softener include:

  • Healthier skin & hair, and reduced issues with dryness and irritation
  • No more scale formation on your pipes, fixtures, and appliances
  • Reduced cleaning efforts due to the lack of scale on surfaces
  • Water that lathers better with soap, reducing your soap use
  • Softer clothes and laundry with reduced fading
  • No white spotting on glasses and dishware
  • Improved appliance efficiency and longevity

Some of the benefits of a reverse osmosis system include:

  • Environmentally friendly; enjoy clean water at home with no need to buy bottled water
  • Improved water quality because contaminants affecting taste and odor are removed
  • Purest drinking water that’s safer and healthier than normal tap water
  • Soft water (although hard or very hard water will damage the semipermeable membrane)

Combining water softeners and RO systems also means combining their benefits.

Related Article: Can you use reverse osmosis water in a humidifier?

Filling a glass with tap water

πŸ€” Should I Buy a Water Softener and a Reverse Osmosis System?

You don’t have to buy a water softener and an RO system if you don’t want to.

But we recommend thinking carefully about the sort of solution that will help you to save money and get the best value from your purchase in the long run.

RO systems can help you to save hundreds of dollars a year by ditching the bottled water, and water softeners save energy by preventing a decline in appliance efficiency caused by scale formation.

πŸ‘¨β€πŸ”§ If treating hard water is your top priority, the more economical solution is to install a water softener. Why? Because RO systems waste water and hard water will damage the membrane, increasing your maintenance costs. You may as well go with the solution that’s specifically designed for hard water treatment if that’s your biggest issue.

πŸ‘¨β€πŸ”§ If you’re most keen to purify your water, an RO system makes the most sense, since water softeners don’t filter water – they just address water hardness issues. Reverse osmosis removes more contaminants than any other water filter type, so we recommend this method of treatment if your priority is making your water as clean and safe to drink as possible.

However, if you’re torn between the two systems and your budget will allow it, it makes the most sense to buy them both, since a water softener will protect the RO system, so it can perform optimally throughout its lifespan.

  • Brian Campbell
    Founder, Water Treatment Specialist

    Brian Campbell is a water treatment specialist and water expert based in Denver, Colorado. He's always been obsessed with water quality, and has spent years testing all kinds of treatment devices from simple pitchers and portable devices to complex whole home systems.

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