Water Softener vs Filter — Which One Do You Need?

Updated on:
March 8, 2024

In your quest for the best water filtration system for your home, no doubt your neighbor has suggested installing a water softener and your other neighbor says you need a water filter. What’s the difference? How do these two technologies compare and do you need both to achieve your water quality goals?

You can’t make the best decision for your home and family until you understand what each device removes from your dodgy water.

To put it simply, a water softener addresses hard water, while a water filter removes all the impurities to make your water clean and drinkable.

Let’s dig deeper and find out which is best for your needs.

What Is a Water Softener?

A water softener is specifically designed to soften water by reducing the amount of hardness-causing minerals—calcium and magnesium—in the water.

To fully understand the use of a water softener, it’s important to understand the basics of hard water.

What is hard water?

Water that contains a high amount of dissolved calcium and magnesium minerals—up to 121 to 180 mg/L—is considered hard water. The ground beneath our feet is a mixture of many minerals. As water passes through the rocks and soil of the earth’s crust, it absorbs these minerals and carries them to the water supply.

Did you know that almost 85% of the US has hard water? Some areas have larger deposits of minerals than others, of course, which is why the mineral makeup of water varies from region to region. Minerals in water are also the result of unmindful human activities like farming and unsupervised industrial waste disposal.

You can’t tell if your water is hard just by looking at it, but there are other ways to recognize it. Here are some common signs of hard water:

  • Hard water makes it hard to rinse soap away from your skin, thanks to the reaction between soap compounds and the calcium and magnesium minerals in the water. A resulting chalky and grayish film firmly adheres to the skin and takes a lot of time and scrubbing to rinse off.
  • Mineral-laden water damages your skin and makes your hair dry, dull, and brittle. Hard water can even trigger skin conditions, such as eczema and dermatitis, if you have sensitive skin.
  • You’ll notice hard water scale buildup around toilet rings, bathtubs, sinks, floor tiles, showerheads, shower curtains, and faucets. If not cleaned in time, it can attract mold and give off a bad smell.
  • Hard water will leave white and powdery stains on washed clothes and kitchenware. 
  • Instead of a fluffy lather, hard water will form detergent curds and reduce the life of your favorite wardrobe items and utensils.
  • If you’re experiencing fluctuating water pressure around the house, you probably have a lot of scale buildup in your pipes and plumbing system. Hard water scale buildup can clog pipes and make the inner diameter narrower by depositing minerals.
  • Mineral-laden water is also responsible for clogging the systems of the appliances that use water, such as your dishwasher, water heater, washing machine, coffee maker, and refrigerator.
  • Hard water tastes salty and bitter. Although drinking hard water has no significant adverse effects, it lacks freshness and may discourage you from fulfilling your daily water intake.

How do water softeners work?

A water softener uses ion-exchange technology to swap calcium and magnesium minerals in water with sodium (or potassium in some designs). In essence, it is a type of water filter that treats and removes only magnesium, calcium, and a small concentration of iron.

It contains a bed of negatively charged plastic resin beads treated with positive sodium ions. As the water passes through the resin, the positive calcium and magnesium ions are trapped by the anionic bed.

This process continues until the resin bed is saturated with calcium and magnesium ions and can no longer capture minerals further. At this point, the water softener regenerates itself by washing the resin bed with a sodium chloride solution. Sodium replaces the captured mineral ions, which are flushed down the drain.

If you’re on a low-sodium diet and concerned about the increased sodium levels in your water, opt for a water softener that uses potassium instead of sodium. However, you should know that potassium salt is a tad more expensive and harder to find in stores. Also, a potassium-based unit (also called salt-free water conditioner) is not as effective as a sodium-based water softener.

What Is a Water Filter?

Water filtration equipment can remove all kinds of pollutants from water, such as dirt, bacteria, viruses, chlorine, sulfur, heavy metals, minerals, volatile organic compounds (VOCs), fertilizers, herbicides, and other chemical compounds.

Not only are water filters suitable for removing toxic impurities, but some filters can also retain useful minerals and electrolytes in water so you can drink healthily. By removing minerals and other contaminants, water filters will significantly improve the life of your pipes and appliances. You won’t have to spend hours scrubbing the scale and mineral deposits off your fixtures. Washing laundry in filtered water improves the life of your clothes and makes them look brighter.

Ultimately, a drinking water filtration system that can remove as many contaminants as possible makes it safe for you and your family to drink, and a water softener can’t do that. Water filters make your water squeaky clean, fresh, and delicious by banishing nasty organic and chemical odors and tastes. There are many different types of water filters, though, and it can be hard to choose the best one for your needs.

Types of water filters

Water filters use many filtering technologies to tackle one or a combination of contaminants. A few of the most popular filtering systems include activated carbon, air-injection oxidation, ultraviolet treatment, and reverse osmosis. Water filters come in many sizes and designs, such as countertop filters, under-sink filters, water pitchers, tap attachments, and whole-house systems.

Depending on your region and the particular cocktail of contaminants you’re dealing with, you might need to install a combination of these units to remove all the impurities in your water.

Activated carbon

Activated carbon, or carbon block, filters use porous carbon to capture odor-causing chlorine, chlorine by-products, and sulfur compounds in water. Some carbon filters can also reduce the amount of fluoride and lead in water. But activated carbon cannot treat bacteria, viruses, or other organic and inorganic compounds.

Carbon filtration units are easy on the pocket and cost around $500.

Air-injection oxidation (AIO)

Air-injection oxidation is designed to oxidize soluble metals in the water into insoluble metal compounds that precipitate out easily. These systems require periodic backwashing and regeneration to remove the accumulated metals oxides in the filters and replenish the oxygen in the tank.

AIO filters can tackle massive amounts of iron, sulfur, and manganese without using any chemicals. This system will cost you around $600–$1,500. 

Ultraviolet filter

UV filters are designed to clean all the microbial contamination in water. UV rays destroy the cell walls of living organisms in water, making them inactive and impotent. These units, however, cannot tackle solid particles, heavy metals, and other chemical pollutants in water.

UV filters will cost you around $800.

Reverse-osmosis system (RO)

Reverse osmosis uses a semipermeable membrane of pore size 0.0001 microns to filter almost 99% of the contaminants in the water. From microbes to heavy metals, a reverse-osmosis system with its multistage design—including sediment and carbon filters—can make your water super clean and healthy.

Whole-house RO systems run from $1,000 to $4,000 depending on the quality and size of the unit. Countertop and under-sink models are more common than whole-house ones, and much more affordable. Depending on which you choose you could spend less than $100 on a countertop system or $150–$600 on an under-sink system.

So, Which One Should You Buy—Water Softener or Water Filter?

The answer to this question lies in your water test results.

You first need to test your water, either at home or in an accredited laboratory. Many affordable water testing kits are available online and in local home improvement stores that can test for a wide array of contaminants. If you want to analyze your water quality more accurately, you can always contact a nearby laboratory and send them samples of your tap water.

You can also demand an annual water quality report from your local water supplier to get a general idea of what is lurking in the groundwater.

Why get a water softener?

If your test results indicate the presence of only calcium and magnesium in high amounts, you need to invest in a whole-house water softener system. The up-front cost of a water softener is a little high, but it pays off tremendously in the long run. The equipment will cost around $1,500 and you can expect to spend around $200–$500 on its installation.

Water-softening systems are usually available as whole-house equipment because the destructive effects of hard water extend beyond just drinking water. As I mentioned earlier, hard water can deposit minerals into every corner and crevice of your plumbing fixtures and water-using appliances. Using a water softener will save you a lot of the money, effort, and time that goes into the maintenance of your plumbing system and the electricity bills of your clogged appliances.

Soft water, when mixed with soap, will form a light, bubbly lather that will clean your skin, hair, and laundry perfectly. You can forever bid farewell to the detergent curds and clumps in washing machines and dishwashers.

Why get a water filter?

If your test results indicate the presence of other contaminants, like bacteria, arsenic, chlorine, lead, or sulfur, you need a water filtration system. A water softener system is only good for hard minerals.

A whole-house water filter is the best choice for all your water problems. If your tap water has suddenly turned yellow or smells like rotten eggs, or your water supply has a high concentration of chlorine and its dangerous by-products, a purification unit like reverse osmosis will take care of every pollutant.

You can even resolve moderately hard water with an RO unit, but I recommend you install a water softener if you have very high concentrations of hard minerals. RO membranes can clog with excessive salt and mineral sediments, and frequent filter replacements will set you back hundreds of dollars. Ion swapping in an ion-exchange water softener is the best way to treat hard water.

Do you need a water softener if you have a water filtration system?

If you’re super unlucky and have hard minerals and other contaminants in your water supply, you need to invest in both a water softener and a water filter.

A water softener will soften your water effectively but you still need a drinking-water filtration system to remove other harmful contaminants that could be fatal to consume.

The most common and popular configuration in areas with very hard groundwater is a water softener at the point of entry (where water enters the home) followed by a reverse-osmosis filter at the point of use (usually the kitchen sink). 

In cases where water is laden with multiple dangerous contaminants, you might consider a whole-house water filtration system that treats all the water coming to your house. Some contaminants can be absorbed in your skin while bathing and showering, so it is essential to treat water coming from all the taps and not just your kitchen sink. 

Moreover, instead of buying water conditioners, softeners, and filters separately, you can go for an all-in-one whole-house filter that combines filters and water-softening technologies to treat all kinds of problems in your water supply. Needless to say, expect this to be an expensive choice.

Final Thoughts—Water Softener vs Filter

If you’re suffering from excessive scale buildup in your shower heads, toilet rings, tubs, and tiles, you have high mineral content in your water. Hard water dries your skin, makes your hair dull and brittle, and damages expensive appliances. In this case, a water softener is your best bet.

But water softeners cannot treat any other pollutant in water, so you may still need to invest in a water filter to make your water drinkable. Water filtration systems like activated carbon, reverse osmosis, and UV filters will improve the taste, color, and smell of your drinking water while making it safe to consume.

In the end, it boils down to what contaminants lurk in your water. Get your tap water tested to decide which equipment is best for your needs. And then get moving on the right system for your home. Safe water is a necessity for everyone. 

If you’re in search of further information regarding various water filters and the distinctions between them, we invite you to explore our articles comparing “Faucet Filter vs Pitcher Filter,” “Difference Between a Water Softener And a Water Conditioner,” “Is Reverse Osmosis Water The Same as Distilled Water?,” “Distilled vs Purified Water,” and “Berkey Vs Reverse Osmosis: Which is Best For You?” These resources will provide valuable insights into the dissimilarities and advantages offered by each filtration system.

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