Adding a water softener is a popular option for homeowners if they live in an area with very hard water. At the bottom of this article you’ll see links to all my articles on water softeners given my personal experience with both basic manual models and higher end fully automated ones.
But what about a reverse osmosis system? Is this something you need in your home especially if you already have a whole house water softener?
Since they perform different functions, a reverse osmosis system can be used in conjunction with a water softener to provide water that has been filtered to remove contaminants while also removing dissolved solids.
Below we’ll take a look at the purpose of both reverse osmosis systems and water softeners as well as pros and cons and options that are available.
Can I use a water softener in conjunction with a reverse osmosis system?
Yes, you can use both a reverse osmosis system and a water softener in your home. While you don’t have to use both in conjunction with one another, you can do so if the benefits that each offer make sense for your household.
A reverse osmosis (RO) system is used to remove contaminants from water to make it tastier to drink and cook with. When water is highly concentrated with certain contaminants it can not only be a concern to your health but perhaps more noticeably to your drinking water and water used for cooking.
A water softener is used to remove high levels of dissolved solids from your water which offers benefits to your skin and hair while bathing, to your clothes when they are being washed and to your pipes and water-using appliances. Hard water – which has a high degree of dissolved solids such as calcium and magnesium – is harder on the body, clothing and your pipes which is why softened water is desirable.
What does a reverse osmosis system do?
A reverse osmosis system is a water filtration system that can reduce up to 98% of contaminants in water depending on the model and quality of the system installed.
An RO system uses a semi-permeable membrane which means it allows water through but the holes are small enough to block certain dissolved solids. The water is forced through under some pressure – about 35 pounds per square inch – so the process is unlike your water pitcher where water seeps through a charcoal filter using gravity.
A quality RO system can remove contaminants like pesticides, herbicides, lead, mercury, chromium and total dissolved solids as well as other potentially harmful particles.
What kind of RO systems are available?
There are several kinds of reverse osmosis systems that are available depending on how you’re comparing them. Here are the main ways RO systems are classified:
Type of RO systems
Whole house reverse osmosis system – This is typically installed right at the point where the water supply enters your home, probably in your basement if you have one, at the water main. This means that all water that circulates inside the home has been treated by the RO system and is thus filtered.
A whole house reverse osmosis system is an expensive and most likely unnecessary option for US households and those who live in an area with minimum water standards from their municipal water supply.
If you’re on well water and have contamination or multiple problems you can’t rectify such as high levels of dangerous chemicals, then an RO system might be worth studying.
Undersink reverse osmosis system – This unit is attached to one single tap in your house – typically the kitchen faucet – and it supplies filtered water to that tap only. The benefit of this option is that it’s cheaper to install. The downside is that it only supplies filtered water to one particular part of your home.
It’s a cheaper and quicker option for someone who would like water filtered by an RO system but doesn’t want or need a whole house RO system.
Type of RO filters
You can also segment reverse osmosis systems by filter type. Quality RO systems don’t have a single filter but several levels of filtration, up to 5 in fact. Often this includes a pre-filter to immediately remove sediment along with multiple levels of other filtration up to and including a post-filter option at the end.
The common filter types are:
Thin Film Composite – Also known as TFC or TFM (Thin Film Membrane), these are very common in household RO systems and stop about 98% of contaminants.
The issue with this filter type is that it can only be used with chlorine-free water so if you water has a high level of the chemical, it may not be suitable.
Cellulose Triacetate – Also known as CTA, this membrane tends to stop about 93% of contaminants from remaining the water supply.
Why would I need a reverse osmosis system in my home?
If you’re the type of person who notices differing taste of water depending on the source, an RO system might be right for you.
If you live in an area known to have tasteless or poor tasting water or have a supply that includes the presence of pesticides, herbicides and other harmful chemicals, you may benefit from an RO system.
As mentioned above, a whole house RO system may be overkill unless you live in an area with contaminated water or water that has multiple problems that you haven’t been able to solve.
But an undersink, one tap reverse osmosis filter in your kitchen might be something you invest in for personal reasons to improve the taste of your water for drinking and cooking reasons.
And if you live in an area known to have clean, decent-tasting water and you’ve had the water tested and determined it’s well within various chemical limits, you may not even benefit from an RO system.
Pros and cons of a reverse osmosis system
The main purpose of a reverse osmosis (RO) system is to remove contaminants from water that can be dangerous to consume in large amounts and that can negatively impact the taste of the water.
Here are the main pros and cons of a reverse osmosis system in detail.
| Reverse osmosis system pros | Reverse osmosis system cons |
| A whole house system installed at the main water source coming into your home provides filtered water for the whole house. You may also choose an undersink option for a dedicated filtered water supply. You have choices depending on what you need. | High up front cost: A whole house system may cost around $1,500 on average although an under the counter single tap option will be cheaper. |
| Modern RO systems are fully automated and operate on their own. | There is routine maintenance and filter changes required on your part typically every 6-9 months. Cleaning and sterilization is often once yearly. |
| People often note better tasting water and better tasting food that was cooked with water purified by an RO system. | System clogging is common due to the small pores in the system which may get blocked from chlorine in the water. |
| A quality RO system might last 10-15 years so it can work for some time when properly maintained. | Whole house RO systems are generally unnecessary when you’re on a municipal water supply which is governed by minimum standards. |
| Higher end systems with the best water filtration systems can remove up to 98% of contaminants which can help solve otherwise troublesome water contamination problems. | Tends to use a significant amount of water at a rate of 4:1 i.e. 4 gallons of water are needed to produce 1 gallon of filtered water. |
Does reverse osmosis remove hardness of water?
While an RO system can remove salt from your water supply, its main purpose and design is to filter out harmful contaminants at a rate of up to 98% for the best systems. Its ability to remove large amounts of the minerals that make water hard – calcium and magnesium – is not as good.
That’s where a water softener comes in. Its design and purpose is to remove high levels of calcium and magnesium by way of a salt brine and thus turn hard water into softened water.
This is why use of a reverse osmosis system in conjunction with a water softener may make sense for you: The RO system removes harmful contaminants and then the water softener removes the harsh minerals like calcium and magnesium that make water hard.
If your main goal is to reduce water hardness and have soft water in your home, a water softener is a better choice.
Summary
Using a reverse osmosis system in your home along with a water softener can make sense if you need to remove harmful contaminants while also dealing with hard water. If you’re on a municipal water supply, you can most likely forego a whole house RO system but can still use an undersink one for your kitchen.
Then you can use a water softener to remove calcium and magnesium from your water to make it soft which provides benefits when showering and bathing as well as being easier on your pipes and appliances that use water. It can also reduce your detergent usage since soft water is generally better for washing.
Since being on a municipal water supply ensures minimum water standards that must be provided, you’re more likely to require a water softener since many water supplies are naturally hard.
If you’d like to learn more about water softeners, I’ve written a few other articles on this website:
5 Common Problems With Water Softeners