Is Reverse Osmosis Water Hard Or Soft?

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You probably know that reverse osmosis removes virtually all drinking water contaminants. But does this purification process produce water that’s hard or soft? Does it have an effect on your initial water hardness?

Find all the answers you need to know in this short guide.

📌 Key Takeaways:

  • The water produced by a reverse osmosis system is soft because RO purification removes virtually all dissolved minerals, including calcium and magnesium.
  • However, the reverse osmosis process is different from the water softening process, which exchanges hardness minerals with sodium ions and is intentionally designed for long-term softening.
  • You can enjoy the best benefits of softened, filtered water by installing a water softener alongside a reverse osmosis system.

🤔 Is Reverse Osmosis Water Soft Or Hard?

Water from a reverse osmosis filter is soft because it’s free from all minerals, including hardness minerals.

Calcium and magnesium minerals are responsible for hard water scale. These minerals are naturally present in most drinking water supplies.

The RO process removes all dissolved minerals in water, including calcium and magnesium. That means that RO water is classed as soft water.

Keep in mind that most reverse osmosis systems are point-of-use (POU) units, meaning that they provide purified tap water to a specific sink or faucet. So, if you want to enjoy soft water benefits around your home, you’ll need to install a softener.

Filling a glass with filtered RO water

🆚 Water Softening Vs Reverse Osmosis Process

How do the water softening and reverse osmosis processes differ?

The main differences are the treatment method itself and the intended end result.

Water Treatment Process

The treatment process in a water softener is ion exchange. This process takes place in the resin tank, which contains a resin bed that’s loaded with sodium ions.

When water flows into the tank, the hard minerals are attracted to the resin bed. These minerals stick to the resin, and equal amounts of sodium (or salt) ions are released into the water to balance out its charge.

The treatment process in an RO system is a type of filtration known as membrane separation, which occurs in the RO membrane. This membrane consists of hundreds of tiny pores, which are so small that only water particles can pass through. The majority of total dissolved solids (TDS) are drained out of the system with wastewater.

All contaminants, including heavy metals, chemicals, and minerals like calcium and magnesium, are removed, resulting in pure water.

Intended End Result

The intended end result of a water softener system is to eliminate the effects of hard water, including scale buildup and soap scum, by softening the water. Water softeners also reduce iron, copper, and a few other contaminants, but their main purpose – and what they’re best at – is water softening.

The intended end result of a reverse osmosis system, on the other hand, is to produce the purest drinking water, making it clean and safe by removing all impurities. It just so happens that water is softened as part of this process.

Water filter versus reverse osmosis system comparison

🚰 Benefits Of Using A Water Softener To Treat Hard Water

The obvious benefit of using a water softener to treat hard water is that it’s specifically designed for this purpose.

The main role of a water softener is to soften water. The ion exchange process is highly effective at this job, eliminating hard water minerals and preventing scale formation and other hardness issues in your plumbing system.

A reverse osmosis system, on the other hand, is designed to filter water, and too much water hardness could be detrimental, resulting in scale formation on the surface of the RO membrane and reducing its performance efficiency.

Another benefit of water softeners for treating hard water is that they’re installed as point-of-use systems upstream of your water heater, so they provide soft water throughout your home – including in all your appliances and fixtures. That means you get the best value for money from your purchase.

Some reverse osmosis systems are also designed for POE installation, but these systems are about 7x the cost of a water softener and waste a lot of water.

Limescale before after water softener install

⚗️ Benefits Of Using A Reverse Osmosis System To Treat Hard Water

The biggest benefit of using an RO system to treat hard water is that this system doesn’t only remove hardness minerals – it also removes the majority of other total dissolved solids, meaning that you get soft and purified water in one.

A water softener can’t compete in this aspect because it’s not intended to be a purification solution. So, if you want to improve your water quality as thoroughly as possible, a reverse osmosis filter could be what you’re looking for.

Another benefit of RO water filtration systems is that they help you to save money and reduce your environmental impact by ditching the bottled water. If you currently drink bottled water rather than water from your faucet, installing an RO system should offer a more economical solution.

Still, despite their benefits, we don’t recommend exclusively using RO systems to soften water because of two reasons:

  1. Hard water scale will damage the semi-permeable membrane.
  2. An under-sink or countertop RO system won’t protect your plumbing system from hardness minerals.

If you want to enjoy the benefits of soft and pure water, installing both a water softener and an RO system is best.

Related: Is distilled water soft or hard?

❇️ Benefits Of Installing A Water Softener And A Reverse Osmosis System

Let’s take a look at the key benefits of installing a water softener and an RO system together.

Provides All-In-One Water Treatment

If you want to soften water and improve its taste and health properties, you can only effectively achieve this in the long run with a softener and an RO unit.

Money-Saving Solution

Water softeners save energy by improving appliance efficiency, and RO systems are both penny-saving and environmentally friendly because they eliminate the need for bottled water. Installing both these systems together can help you to save money – and your investment should soon pay for itself.

Faucet water flowing

Sustains The RO System Performance

Finally, installing a water softener before a reverse osmosis water filter helps to protect the semi-permeable membrane and lengthen its lifespan. RO systems are better at filtering soft water, since there are no hardness minerals to reduce the system’s efficiency and damage the membrane.

🙋‍♂️ Should You Install A Water Softener, A Reverse Osmosis System, Or Both?

You might only need an RO system or a water softener – or you might benefit the most from both.

👨‍🔧 If your main water quality issue is limescale and your top priority is to resolve your plumbing issues and enhance the performance of your household appliances, you need a water softener.

👨‍🔧 If your main water quality issue is contaminants affecting water taste and your top priority is to drink tastier, healthier water, you need an RO filter.

However, if you want clean water that’s safe to drink and will protect your entire home from mineral damage, you’ll do best with a water softener and an RO water filter.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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