Wondering if you should install a whole house water filter before or after a water softener? Most of us in developed nations have easy access to drinking water, but not all tap water is equal.
This is why many people turn to water filter and softening systems to improve their household’s water quality. Water filtration and softening are two different devices with two different jobs.
So what comes first? The answer depends on your water source, the type of softener you use, and how your filtration system is staged.
For municipal water, install your carbon water filter before the softener to remove chlorine that damages the resin bed. For well water, install a sediment pre-filter first, then decide on softener placement based on flow rate needs and your specific water quality.
Water Filtration vs Softening
Before deciding on installation order, you need to understand what each system does. They serve completely different purposes.
Water Filtration
Water filtration is a process that reduces or removes contaminants and impurities from the water supply. These include particles such as iron, salt, and more.
This is usually for drinking water. The impurities being filtered include parasites, bacteria, fungi, viruses, as well as chemical or biological contaminants such as pesticides, iron, sulfur, and fluoride.
There are three main methods of filtering water:
- Physical barrier filtration
- Biological process filtration
- Chemical process filtration
Many filtering systems use a combination of these methods in their various filtration stages. The end product after filtration will have unequal levels of purity depending on the quality of the system.
Please note that no water filtration system can remove 100% of contaminants.
Water Softening
Softening is the process of removing calcium and magnesium found in “hard water.” Water softening doesn’t reduce contaminants such as iron.
Instead, it only deals with hard water minerals.
The problem with hard water is that it causes scale buildup in appliances and plumbing, shortening their lifespan. You’ve probably seen scale buildup in your kettle or coffee maker.
The scale (or limescale) is the result of calcium and mineral deposits that have dried up and stuck to fixtures, appliances, or your water line. Although a kettle is easy enough to descale, it’s a lot harder when you’re dealing with washing machines, dishwashers, and plumbing pipes.
By preventing hard water from entering your appliances in the first place, you can prevent this scale buildup. This makes sure your appliances last longer.
Soft water also allows you to use less soap to clean. Your clothes may wear out less quickly with repeated washes as well.
Hard water isn’t a health issue, but it’s a nuisance for many households.
| Feature | Water Filter | Water Softener |
|---|---|---|
| Purpose | Removes contaminants (bacteria, chemicals, metals) | Removes calcium and magnesium (hard water minerals) |
| Health Impact | Improves drinking water safety | Not a health issue, prevents scale damage |
| Targets | Parasites, pesticides, iron, chlorine, VOCs | Calcium, magnesium (hardness minerals only) |
| Benefit | Cleaner, safer drinking water | Longer appliance life, less soap needed |
Do You Need A Water Softener If You Have A Whole House Filter?
Whether you need both a water filter and a water softener depends on the kind of water that comes into your home. Generally, most of the USA has hard water.
However, you should be able to get a water report from your local water provider to find out more about your particular water supply. If you use a private well or rainwater, you can get the water tested by a certified lab for hardness.
This can help you decide exactly what kind of system to consider installing.
Why Do I Need All The Water In My Home Softened?
Even if you’ve a whole house water filtration device installed, you can still have hard water with all the problems it causes. To change hard water into soft water, you need a softening system.
There are several advantages to installing a whole house softening system:
- Whites stay whiter without the gray caused by hard water
- Appliances may last longer as scale won’t build up
- You don’t need to remember to remove scale from your washing machine, dishwasher, and other appliances
- The pipes may last longer without scale buildup
- Reduced soap curd makes cleaning easier and quicker
- You’ll use less soap and shampoo, which saves you money
If you only clean and soften your kitchen tap with an under-sink device or use a countertop system, you lose these whole-home advantages. This is why it’s much better to install a whole house water softening device if you live in a hard water area.
How Does A Water Softening System Work?
There are essentially two types of water softening systems: salt-based and salt-free. A salt-free softener is usually called a water “conditioner” as it doesn’t truly soften the water.
Salt-free devices are generally considered healthier as they don’t add sodium to the water. Some cities are even banning traditional salt-based systems for health and environmental reasons.
Although salt-free systems are effective at preventing scale and even eliminating pre-existing scale buildup, they don’t provide many of the benefits of actual water softening. Which system you choose depends on where you live, the hardness of your water supply, and your personal health goals.
Salt-based softeners use ion exchange to truly soften water, but they add sodium and need more water flow for backwashing. Salt-free conditioners prevent scale without adding sodium, but they don't provide all the benefits of true softening. Your choice depends on your water hardness, health goals, and local regulations.
What Types Of Water Filtration Options Are There?
There’s a range of options for filtering the water you use at home:
- Portable water filters that you can use on the go
- Fridge water filters that connect to your refrigerator for cold filtered water
- Countertop water filters that you refill from the tap
- Under-sink water filters that clean water for just one tap
- Whole house water filters that clean all the water used throughout your home
All these filtering systems are available at different price points and quality levels.
What Is A Whole House Filter?
Installation for whole house water filters should be at the Point of Entry (PoE), right after the water meter. This means that all the water in your house is filtered, including the water for your washing machine, toilets, dishwasher, all taps, your bath, and shower.
By having all the water in the house filtered, you don’t have to remember to grab the “special” water from the filter jug or use a separate tap on the sink. A whole house water filter also means your shower water is free from vapors created by standard treated municipal water.
The convenience and health benefits of whole house water filters have led to the increasing popularity of these systems.
As you can see, water softeners and water filters perform different jobs. In a whole house setup, both the filtration equipment and water softener need to be installed as close as possible to the point of entry.
The question of where to install the softener relative to the filter is more complex than it first appears. Your water source plays a major role in determining the installation order.
Where Do You Get Your Water From?
Households get their water from different sources, and each source affects how you set up your filtration and softening system.
Well Water
Around 13 million people in the US get their water from a private well. Wells are supplied by groundwater or aquifers.
Because well water comes from groundwater, the quality can be affected by seepage from fertilizers, underground fuel tanks, failed septic tanks, landfills, and other runoff. Our guide on installing a whole house water filter on a well covers the specifics. If you get your water from a well, you want to test it regularly to make sure you’re not ingesting heavy metals, harmful chemicals, or pathogens.
The Centers for Disease Control and Prevention recommends that you get your well tested every year.
Another consideration with well water is turbidity. Turbidity is the measure of the clarity of a liquid.
Things that cause water to be turbid include clay, silt, as well as other inorganic and organic matter.
It’s important that you know the well water quality before installing a water system. A well water setup starts with a pump to bring the water to the surface and then a water pressure tank to provide pressure.
You can install any filter or softener after the water pressure tank but before any taps, appliances, or faucets.
Rainwater
Rainwater harvesting is becoming more popular, especially as droughts and depletion of groundwater aquifers are increasing. A rainwater harvesting setup is similar to a well water setup.
You harvest the rainwater in tanks, taking care to keep foreign matter and debris out with screens. Then it goes into a pressure tank followed by a filtration system.
Filtration systems for rainwater usually contain a UV stage at the end or a chlorine injection stage to disinfect the water and be sure to it’s free of pathogens.
Rainwater is a naturally soft water source as it doesn’t contain the dissolved minerals found in streams, groundwater, and municipal water. Although rainwater will need thorough filtration since it’s vulnerable to environmental pollution, you won’t need a water softener.
Municipal Water
If you’ve municipal water (sometimes called town water or city water), it’s most likely treated with chlorine compounds. Many people don’t like the taste and find the vapors when showering bothersome.
When installing a water filter, you’ll want to choose one that especially targets chlorine, such as a carbon filter. Getting rid of the chlorine taste is one of the main reasons people choose a filtration system.
Municipal water enters the home usually at ground level or below. You install any systems as close to the point of entry to your home as possible.
| Water Source | Key Concerns | Softener Needed? | Special Considerations |
|---|---|---|---|
| Well Water | Sediment, heavy metals, bacteria, turbidity | Usually yes | Annual testing recommended, sediment pre-filter critical |
| Rainwater | Pathogens, environmental pollutants | No (naturally soft) | UV or chlorine disinfection stage needed |
| Municipal Water | Chlorine, chemicals, lead from old pipes | Usually yes | Carbon filter to remove chlorine taste and protect softener |
Filtration Stages
To decide whether your water filter should come before or after your softener, you first need to understand the different stages in a filtration system.
Generally, a filter starts by trapping the largest particulates in your water supply. From there it works its way to finer particles such as iron.
Each filtration stage has a well-defined purpose in targeting specific contaminants.
The Three-Stage Process
A common three-stage filtration device starts by filtering out the larger particles through a filter, often with a 5-micron pore size. That filter blocks every particle larger than 5 microns, but smaller particles still pass through.
Even though the sediment pre-filter only catches the largest particles, it plays a key role. It keeps the next-stage filters and your water softener functional for a longer period.
Without this pre-filter, the other stages would need more frequent filter media changes. They would get blocked more quickly with the larger particles.
The next two stages are often carbon filters. This includes a Granular Activated Carbon (GAC) filter to remove some of the chlorine taste, odor, and other contaminants.
An Activated Carbon Block (ACB) stage uses fine powder to filter out even more chlorine from treated municipal water, along with chemicals, contaminants such as lead, and volatile organic compounds (VOCs). The downside of the activated carbon filter is that it can reduce the flow rate, which is a consideration when combining it with a salt-based water softener.
Additional Stages
Additional post-filter stages can be added to a filtration system, including reverse osmosis, ion exchange, ultraviolet disinfection, and ionization. Your personal health goals, the particular contaminants in your local water supply, and your budget will influence what kind of treatments you want to install.
Every filtration system should start with a sediment pre-filter to protect downstream equipment. Carbon stages remove chlorine and chemicals but can reduce flow rate. This flow rate reduction is important to consider when placing a salt-based softener, which needs strong flow for its backwash cycle.
Where Should A Whole House Water Filter Be Installed?
You now understand that the source of your water influences how you set up your filtration system. You also understand that filtering systems have different stages, each with their own purpose.
Where you install your filter and your softener in a whole house system depends on your specific situation. Here are some general guidelines.
Well Water System Installation
In a well water system, it’s recommended to install a pre-filtering stage after the pressure tank to remove the larger particulates. If the turbidity of your well water is high, you’ll especially want to use a sediment filter.
Sediment filters are relatively cheap to replace. By installing them at the start of your setup, you protect all your other filtering and softening equipment.
If you use a salt-free conditioner: Run the water through the carbon filtering stages and then through the conditioner, followed by any post-filtering stages such as UV disinfection or ionization.
If you use a salt-based softener: The softener needs more water flow for proper backwash. The backwashing cycle is when water runs through the resin tank “backward” at a fast speed to flush minerals from the resin bed and out to the drain.
The filtering stages can reduce the flow of the water. If that’s the case, you can install the water softener before the carbon stages but after the sediment filter to protect your equipment.
Another option is to install a higher-quality carbon filter that still offers a good flow rate for the water softener. Since there’s no chlorine in well water, you don’t need to filter before the softener to protect the resin from chlorine damage.
Municipal Water System Installation
Most municipal water is treated with chlorine compounds. Chlorine is a highly efficient disinfectant added to public water supplies to kill disease-causing pathogens such as bacteria, viruses, and protozoans.
As good as chlorine is at disinfecting water, it unfortunately deteriorates the resin in water softening systems. This is the reason you would install your water filtering system before the water softener.
However, some people argue they would rather “sacrifice” the resin bed and replace it more often than have bacteria or microorganisms sitting in the resin tank. Allowing chlorinated water to enter the softener would prevent any pathogens from taking hold there.
Another consideration is the flow needed for the backwash of a salt-based water softener. This concern can be addressed by choosing a carbon filter with a good flow rate that’s still sufficient for the softener.
| Water Source | Installation Order | Reason |
|---|---|---|
| Municipal (salt-based) | Sediment filter → Carbon filter → Softener → Post-filters | Carbon removes chlorine that damages softener resin |
| Municipal (salt-free) | Sediment filter → Carbon filter → Other filters → Conditioner → Post-filters | Conditioners are less sensitive to flow rate |
| Well (salt-based) | Sediment filter → Softener → Carbon filter → Post-filters | No chlorine to worry about, softener needs high flow rate |
| Well (salt-free) | Sediment filter → Carbon filter → Other filters → Conditioner → Post-filters | Conditioner placed after filtration stages |
Selling Your House: Take Or Leave The System?
The purchase of water treatment equipment is an investment in your home. You could consider a properly working water treatment system a selling point, in which case you’ll want to leave it when you move.
Another point in favor of leaving the system is that it’s specific to that water supply. A water treatment system isn’t the same as a refrigerator or microwave.
It not only meets your standards but is also designed with your specific water supply in mind.
Before you decide whether to take the system or leave it, investigate the water supply at your new house. Many homeowners don’t realize that your water can be completely different from the water at your neighbor’s house.
Variations in water sources can make a big difference in what is in your current home’s water versus your new home. The filtration system at your current home may be completely unsuitable for the new house.
It’s also possible that the water supply at your new house isn’t hard at all, meaning you wouldn’t even need a softener. If you do decide to take the water treatment systems with you, make sure to leave all plumbing in good order for the new owners.
Conclusion
The answer to whether you should install a whole house water filter before or after a water softener depends on your water source and setup. Placing any carbon filtration stages before the softener will remove chlorine and protect the softener’s resin bed.
The filters are commonly cheaper to replace than the resin bed in the softener tank. On the other hand, some people worry about the risk of bacteria growing in a softener that receives non-chlorinated water.
A similar concern applies to well water, which is why some well owners inject chlorine into their water tanks. That said, most people opt to install their water softener after their water filtering systems.
The final choice depends on your specific water source and what you aim to achieve with your filtration setup. For any issues or if you’ve a clog, be sure to contact a plumber or professional.
Most people should install their water filter before the water softener. For municipal water, carbon filtration protects the softener's resin from chlorine damage. For well water, always start with a sediment pre-filter, then decide on softener placement based on flow rate needs. The right configuration depends on your water source, softener type, and personal priorities.
Frequently Asked Questions
On city water, carbon filtration goes before the softener. Chlorine eats away at the resin bed, so you want it gone before the water hits the softener. With well water, lead with a sediment pre-filter, then the softener if you're using a salt-based system, and finally the rest of your filtration stages.
A filter and a softener do completely different jobs. The filter removes contaminants, but it won't do anything about hard water. If you've got scale building up in your pipes and on your fixtures, you need a softener too. Get a water test or request a report from your local provider to see what you're dealing with.
You can, but know what you're getting. A salt-free system is really a water conditioner, not a true softener. It'll prevent new scale and can break down existing buildup, but you won't get the full benefits like less soap usage and softer laundry. Worth noting that some cities are banning salt-based systems for environmental reasons, which makes salt-free the only option.
Honestly, you're probably better off leaving it. The system is configured for that specific water supply and may not work as well at your new place. Plus, it adds real value to the property for buyers. If you do take it, just make sure you leave the plumbing in good shape for the new owners.
