Install Water Softener Before or After Reverse Osmosis System?

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One of the most important considerations when it comes to installing a reverse osmosis system alongside a water softener is the order of installation.

You might think that this is irrelevant, but you couldn’t be further from the truth.

Read on to find out what you should actually be doing.

Key Takeaways

  • When using a water softener and reverse osmosis system together, the water softener should always be installed first.
  • That way, the water softener protects the reverse osmosis membrane from hardness minerals which could cause clogging and improves its efficiency.
  • This applies to both point of use and point of entry reverse osmosis systems.

Install Water Softener Before or After Reverse Osmosis System?

So, should you install the water softener before the reverse osmosis system? Or should you install the reverse osmosis systems before the water softener?

In most cases, your reverse osmosis system will probably be at a single point of use, like under your kitchen sink, feeding directly to a dedicated faucet. On the other hand, water softeners are almost always installed at the point of entry, filtering the entire household’s water supply. In this case, it doesn’t make much sense to consider installing the water softener after the reverse osmosis system. A whole house water softener will always come before a POU RO system.

If, however, both of your systems are whole house models, you should pay attention to how you’re installing them. The water softener should always be installed first. That’s because hardness minerals can accumulate on a reverse osmosis membrane and clog pretty quickly. By using a water softener before your reverse osmosis, you can improve the lifespan of the latter.

water softener installation

In addition to that, traditional water softeners add sodium to the water – it’s part of the ion exchange process. This might not be ideal if you’re on a salt-restricted diet or if you’re using that water for your plants, for example. In this case, a reverse osmosis system will help you by removing any excess sodium. But this can only happen if the reverse osmosis system comes later in the filtration chain.

If you are using a salt-free water softener, aka water conditioner, installing it before or after the whole house reverse osmosis system does not matter.

Why Use Both? Do Their Pair Well Together?

Using both a reverse osmosis system and a water softener is quite common. Both systems are designed to address different problems and they can work very well together. In fact, a water softener can somewhat improve the efficiency of a reverse osmosis system and make it last longer.

Water Softeners vs RO Systems – What Do They Do?

The main purpose of a water softener, as the name implies, is to soften your water. It achieves that by removing hard water minerals like calcium and magnesium.

On the other hand, reverse osmosis systems are designed to remove all harmful contamination from your water. While this technically includes minerals, you should not rely on a reverse osmosis system exclusively for softening your water. This will not only decrease the efficiency of the system, but it will also make it clog up faster.

A Water Softener Eliminates Hardness and Protects RO System

A water softener will remove all minerals before water reaches your reverse osmosis system. That way, no minerals will be allowed to accumulate on the reverse osmosis membrane, clogging it in the process. The reverse osmosis membrane will last longer and also work more efficiently in general.

A Reverse Osmosis Removes Contamination and Softening Salt

Once water has passed through your water softener, you might want to run it through a reverse osmosis system to get rid of the excess salt added to it. But the reverse osmosis system will not only get rid of all that sodium, but also all other impurities in the water.

You Get the Best of Both Worlds!

In the end, once water reaches your faucet, you get the best of both worlds. Your water will be as soft as possible while also being free of pretty much all contaminants. As such, you can safely use it for drinking, cooking, and even watering your plants without risking any harm.

Do I Need to Install an RO If I Already Have a Water Softener and Vice Versa?

Whether you need to install one type of system when you already have the other mainly depends on the quality of your water.

  • If your water is “merely” contaminated but not actually hard, you can safely use a reverse osmosis system alone.
  • On the other hand, if your water is simply hard but doesn’t contain any harmful contaminants, you probably don’t need to use a reverse osmosis system and can just go with a water softener.
  • If you have hard water that also contains dangerous contaminants like lead or pesticides, you probably want to use both water softener plus reverse osmosis system.

plumber installing reverse osmosis system under sink

The only way to know which of those is true is to have your water tested. You can buy a kit for testing your water yourself at home, or you can use a professional laboratory service.

We recommend the latter option for various reasons. Most importantly, those DIY kits are not very precise and they are limited in the number of contaminants they can detect. A laboratory analysis, while it would cost you more money, will give you the full picture and you will know exactly what kinds of impurities you’re dealing with.

If you have any questions about installing reverse osmosis before or after the water softener please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
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