(SOLVED) Water Softener Before or After Water Heater?

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Installing your water softener in the right location will help protect your home’s plumbing system as much as possible, without water pressure or flow issues affecting the system’s performance.

In this guide, we’ve shared the answer to the question, “Should I install a water softener before or after my water heater?”

📌 Key Takeaways:

  • In most circumstances, it’s best to install a water softener before (upstream of) a water heater.
  • However, you may need to install a water softener after a water heater if you have no install space upstream of the heater or you don’t want to drink soft water.

📑 Water Softener: Key Points To Know

To understand the pros and cons of installing a water softener before or after a water heater, you need to know what water softening systems are and how they work.

Here are the main facts about water softeners:

  • Water softeners are whole-home systems that soften water.
  • A water softener may be installed alone or alongside a whole house filtration system to improve water quality and prevent limescale damage.
  • Water softeners work by exchanging calcium and magnesium ions with sodium ions, in a process known as ion exchange. This adds a small amount of salt to the water.
  • A water softener can be used with either a well water supply or a municipal water supply.
Water softener system

🤔 Should I Install A Water Softener Before Or After My Water Heater?

In most cases, you should install a water softener before your water heater, as close as possible to your main water supply line’s entry point into your home.

However, there are a few occasions when you might benefit from installing a water softener after a water heater.

It just depends on your priorities and the areas you might be happy to compromise in.

📖 Reasons To Install Water Softener Before Water Heater

Here are the reasons why you should install a water softener before the water heater.

Protects Your Entire Plumbing Supply

The most obvious benefit of installing a water softener before (upstream of) a water heater is that you’ll get softened hot and cold water – not hot or cold water.

The softener will be installed before the hot and cold water lines split off, meaning that your entire home’s water supply is protected against scale and sediment buildup.

Plus, installing a softener at your POE means that any whole house water filter units will also be protected against hard water damage.

If you want to maximize the benefits of a water softener system and get the most out of your investment, you’ll need to install the unit upstream of your hot water heater.

Prevents Scale Buildup In Heater Tank

Installing a water softener before the water heater doesn’t only guarantee a soft, mineral-free hot and cold water supply – it also protects the heating unit itself.

Whether you have an electric or gas water heater, hardness minerals will damage the heater with limescale – a thick, chalky layer of mineral deposits that reduces water flow and heating efficiency. Limescale makes water heaters work harder because it acts as an insulating layer around the heating elements, increasing the time it takes to heat water.

You can completely eliminate the minerals that cause limescale with a water softener, protecting your heater and maintaining its efficient performance. Water softeners can even extend the lifespan of a heating system.

Water heater element with limescale buildup

Correct Water Flow & Pressure

The majority of water softeners are designed to be installed at water’s point of entry into your home, upstream of any gas or electric water heater models. That means a water softener is designed for a certain water pressure and flow rate.

Installing your water softener upstream of the water heater means the system should operate optimally because it’ll have the right flow of water for softening and regeneration cycles. However, this isn’t guaranteed if you install the softener after your water heater, when the flow rate and water pressure are reduced.

Out-Of-The-Way Installation

In most homes, the POE of a water supply line is in an unobvious location, such as a basement or a garage. This is the ideal place to install a water softener, since there’s often enough space for the softener to take up room without being an eyesore in an inhabited part of your home.

New homes with a water softener loop (which massively simplifies the installation process) usually have this loop somewhere out of the way, like a garage.

Some people even install their softened water systems outside, giving them more options to conceal the unit without taking up valuable indoor space. POE locations tend to be nearest to a floor drain for connecting the drain hose, too.

You won’t get as many discreet installation location options if you want to install the softener after the water heater.

Water filtration and softening systems next to water heater

📋 Reasons To Install Water Softener After Water Heater

There are a few reasons why you might want to install a water softener after a water heater.

Puts Less Strain On Water Softener

Installing a water softener after a water heater means that the softener only has to treat your home’s hot water supply. That means the softener does less work because only hot water flows through the system.

Because a lower volume of water is treated, the softener uses salt at a lower rate and regenerates less frequently, so it doesn’t get worn as quickly as a softener that treats an entire home’s water supply.

Less Expensive

Installing a water softener after a water heater also costs less.

You can spend less upfront on a slightly smaller system that’s suitable for your reduced water treatment needs.

Plus, ongoing costs will be lower because the brine tank won’t need as frequent salt top-ups and the sodium in the resin bed will be used at a slower rate, so a regeneration cycle is needed less frequently.

Salt-Free Drinking Water

There are a few disadvantages to only softening your hot water supply – most obviously that the cold water pipes in your home will still be damaged by scale formation.

But one advantage of installing a water softener after the water heater, for hot water only, is that your cold drinking water will still have an enjoyable hard water taste.

That’s because the water will be untreated, so it’ll still contain healthy hard water minerals. If you enjoy the taste of hard water or you’re watching your salt intake and prefer not to drink salt-softened water, you’ll probably want to install a water softener after the water heater.

Municipal treated tap water

🧐 Will A Water Softener Damage A Water Heater?

You may have heard that softened water is corrosive and may damage a hot water heater. This isn’t true.

What is true is that naturally soft water tends to have more corrosive properties because it’s lower in pH and TDS, so it’s “hungrier” and more open to leaching from metals.

That means that a naturally soft water supply could corrode the anode rod in your heater at a faster rate. Eventually, the anode rod could become so corroded that the heater tank itself begins to corrode because it’s no longer protected by the rod.

However, salt-softened water that has been treated in an ion exchange system doesn’t have this problem. This water doesn’t have a low pH or low TDS, so it doesn’t have corrosive properties.

In fact, because salt-softened water is much lower in iron, aluminum, and other culprits of corrosion, installing a water softener before your water heater should actually protect the heater from corrosion.

Continue reading: Water heater with water softener systems: Everything you need to know

❔ Water Softener Before Or After A Water Heater: FAQ

Can you put softened water in a water heater?

Yes. Water heaters, like all water treatment systems in your plumbing setup, are designed to be used with both softened and unsoftened water. The advantage of using softened water in your water heater is that you’ll protect the tank from limescale (which shortens the heater’s lifespan and reduces its efficiency).

How far does water softener need to be from water heater?

Your water softener should be at least 10 feet (in piping) away from the water heater. This should prevent the softener sucking hot water into the system during the regeneration cycle, which could damage the resin bed and plastic tubing.

Does a water softener have to be next to the water heater?

No, a water softener doesn’t have to be next to a water heater – it should ideally be as close as possible to water’s entry point into your home, upstream of the heater. Some plumbers advise installing the softener near your water heater to centralize the appliance, but from what we can tell, this is just a case of personal opinion.

Can you put a water softener on water heater?

No, you can’t put a water softener on a water heater. However, you can install the softener upstream of the heater to protect it from scale formation. Most folks install water softeners at their main water line, before the heater, for this reason.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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