We Condition the Air. Why Don’t We Condition the Water?
We Condition the Air. Why Don't We Condition the Water?
By Mark · US Water Systems · 54 years in water treatment
When I was a little kid, a very, very long time ago, I remember having a huge monster furnace in our basement like this. It was scary. I was sometimes afraid to go down there.
Over the years, furnaces have evolved into what we now call HVAC systems. HVAC systems are no longer just a furnace, but usually an air conditioner, humidifier, and electronic air cleaner or even ultraviolet (UV) disinfection, such as shown below:
HVAC systems today are highly sophisticated because indoor air quality is vital to human health. You can only live for a few minutes without air.
How Long Can You Live Without Air, Water, or Food?
There is an old survival saying known as "The Rule of Threes."
A human being can supposedly survive:
3
Minutes
without air.
3
Days
without water.
3
Weeks
without food.
It is easy to remember, and it gets the priorities right. But the human body does not carry a stopwatch. The real numbers can vary enormously.
What is fascinating is the order.
You can miss dinner for weeks.
You can go for days without drinking water.
But stop breathing and suddenly every second matters.
It's probably for that reason that the HVAC industry is technologically ahead of the water treatment industry in terms of customer acceptance. Most modern homes have the requisite furnace, air conditioner, humidifier, and some type of electronic air cleaning or UV.
What a Modern Home Already Conditions
Furnace: about 60%
The EIA's 2020 Residential Energy Consumption Survey estimated 74.4 million homes used a central warm-air furnace as their main heating equipment, out of about 123.5 million occupied U.S. homes. That's roughly 60%.
That's an enormous installed base.
Air conditioning: 88%, but central A/C is about 67%
About 88% of American households use some type of air conditioning, according to EIA. But that includes window units, portable units, mini-splits, etc.
If we're talking about the traditional ducted HVAC system you're picturing, approximately 67% of U.S. homes have central air conditioning.
So I'd use 67% when talking about an HVAC equipment room or whole-home system.
Humidifiers: about 20% have one, but only a few percent have a whole-house unit
This one is interesting.
EIA's 2015 survey reported about 24 million of 118.2 million homes had a humidifier, or roughly 20%. But that includes portable bedroom humidifiers.
EPA market research found that portable humidifiers dominate the market. It estimated an installed base of roughly 3.5 million whole-house humidifiers at the time, which was only about 3% of American households. EPA also estimated that approximately 350,000 whole-house units were being sold annually, compared with 8 million portable units.
Given subsequent growth, I'd use roughly 3–5% of homes as a reasonable working estimate for an HVAC-mounted whole-house humidifier, while being clear that it is an estimate rather than a current Census/EIA figure.
Electronic air cleaner / UV: probably 10–20%, depending on what you count
This is the hardest category because there isn't a good EIA-style national census asking, "Do you have an electronic air cleaner, or UV lamp installed in your ductwork?"
An EPA study cited an estimate that about 10% of new homes had duct-mounted electronic air cleaners at the time of the research. More recent market research estimates residential UV-C penetration at roughly 12–18% of the addressable residential market, though I represent that as an industry estimate rather than a government statistic.
Share of U.S. homes, by what the HVAC system conditions
Same numbers, same sources as the table below. Tap the toggle at the bottom to read them as a table.
EIA 2020 RECS (74.4M of ~123.5M occupied homes)
EIA (includes window, portable, mini-split)
EIA, ducted whole-home systems
EIA 2015 (~24M of 118.2M homes)
EPA (~3.5M installed); estimate, not a Census/EIA figure
EPA study, at the time of the research
Industry estimate of the addressable market, not a government statistic
the figure as cited the upper end of a stated range or estimate
See the same numbers as a source table Furnace, A/C, humidifier, air cleaner and UV-C, with the citation for each
Scroll the table sideways to see every column.
| What the HVAC system conditions | Share of homes | Source, as cited above |
|---|---|---|
| Central warm-air furnace | ~60% | EIA 2020 RECS (74.4M of ~123.5M occupied homes) |
| Any air conditioning | ~88% | EIA (includes window, portable, mini-split) |
| Central air conditioning | ~67% | EIA, ducted whole-home systems |
| Humidifier of any kind | ~20% | EIA 2015 (~24M of 118.2M homes) |
| Whole-house humidifier | ~3% (working estimate 3–5%) | EPA (~3.5M installed); estimate, not a Census/EIA figure |
| Duct-mounted electronic air cleaner | ~10% of new homes | EPA study, at the time of the research |
| Residential UV-C | ~12–18% | Industry estimate of the addressable market, not a government statistic |
98% of New American Homes Have Central Air Conditioning
So, in the HVAC market, the picture among new homes changes quite a bit, particularly for air conditioning and furnaces. The newest Census Bureau data is excellent here. Of the 1.005 million single-family homes completed in 2025, 984,000 had central air conditioning, or 97.9%. That's dramatically higher than the roughly two-thirds of the overall U.S. housing stock with central A/C.
98% of new American homes have central air conditioning.
Virtually every homebuilder accepts that air should be conditioned before it circulates through the house.
Yet virtually every new house also has another distribution system running through it: the plumbing system.
That system carries water to the kitchen, bathrooms, showers, washing machine, dishwasher, water heater and every faucet in the home.
And unlike central air conditioning, whole-house water treatment is nowhere close to standard equipment.
Why Don't We Condition the Water?
About 98% of new homes have central air conditioning. Yet there is no evidence that anything close to that percentage receives whole-house water treatment. Nationally, only about one-quarter of households have a water softener, even though most softener purchases occur very early in the homeownership period.
Nobody Actually Tracks Water Softeners in New Homes
The evidence, and what it does not say
Three pieces of evidence and the limit of each. Tap any one to read the source in full.
25% of U.S. households own a water softener, and 72% of buyers bought within a year of moving in Water Quality Association, 2021 national survey
The best national evidence I found comes from the Water Quality Association. In its 2021 national survey, 25% of U.S. households reported owning a water softener, and importantly, 72% of people who bought a softener said they bought it within one year of buying or leasing their home. That tells us the first year of home ownership is a huge purchasing window, but it does not mean that 72% of new homes have softeners.
51% vs 17% Newer homes in a hard-water region run far higher, but that is one region Phoenix-area study · regional hard-water market, not a national number
There is also evidence that penetration is much higher in newer homes in hard-water areas. For example, a detailed Phoenix-area study found that 51% of homes built since 2000 had water softeners, compared with only 17% of homes built before 1970. But that was a regional hard-water market, not a national number.
20% to 30% My own estimate, and I am calling it an estimate Mark, US Water Systems · an estimate, not a Census statistic
I would "guess" that roughly 20% to 30% of the population have a softener installed either at construction or shortly after move-in… clearly, this is an estimate rather than a Census statistic.
Homebuilders routinely spend thousands to condition the air before the homeowner moves in but usually hand the homeowner untreated hard water on Day One.
It seems that home builders and homeowners understand that air is vitally important because you can only live a few minutes without it. They know you can live for days without water, so it evidently is not that important to them.
About 85% of the United States Has Hard Water
That number has been cited for years from USGS-based hardness mapping and is echoed by water-industry and extension sources. A Pacific Northwest National Laboratory report provides a slightly more conservative breakdown: almost 75% of homes have water classified from moderately hard through very hard, while other studies put overall hard-water exposure at 80% to 85% of U.S. homes.
And this makes the comparison we've been making much more compelling:
98%
of new homes have central air conditioning.
~85%
of America has hard water.
Only a small percentage
of homes have water softeners.
Yet only a relatively small percentage of homes have water softeners.
In other words:
We automatically condition the air in virtually every new home, even though air conditioning is primarily about comfort. Yet roughly 85% of America has hard water, and we still treat water conditioning as an option.
When a consumer realizes that they have poor water quality, they frequently opt for a water softener, or worse yet, a salt-free water conditioner (notice I did not call it a softener, and there's a reason). Others opt for a filter or a reverse osmosis drinking water system to go with the water softener.
Salt-Free Water Conditioners
Full disclosure: US Water Systems has sold salt-free water conditioners for over 20 years, but we never called them softeners because they did not soften the water, and frankly, the higher the hardness level, the less utility they have. In my 54 years of experience, I have to say this: Salt-free water conditioners work best on water with a hardness between 3.5 and 10.5 gpg (grains per gallon). Yes, I know that some companies say theirs handles water up to 81 gpg, while some say 25 gpg.
Depending upon the characteristics of the water supply, such as alkalinity, Langelier Index, and the ionic composition, a salt-free conditioner may work at levels over 10.5 gpg, but no way they will begin to work at 81 gpg! If someone tells you it will work at 81 gpg, be sure to get that guarantee in writing!
Where a salt-free conditioner actually lands
Hardness in grains per gallon, on one linear scale. Tap a zone to read what the author says about it.
"Salt-free water conditioners work best on water with a hardness between 3.5 and 10.5 gpg (grains per gallon)."
Mark · 54 years in water treatment
"Depending upon the characteristics of the water supply, such as alkalinity, Langelier Index, and the ionic composition, a salt-free conditioner may work at levels over 10.5 gpg."
Mark · 54 years in water treatment
"Yes, I know that some companies say theirs handles water up to 81 gpg, while some say 25 gpg."
Mark · 54 years in water treatment
"…but no way they will begin to work at 81 gpg! If someone tells you it will work at 81 gpg, be sure to get that guarantee in writing!"
Mark · 54 years in water treatment
What a Water Softener Actually Saves You
A water softener can save money in several very concrete ways, and the strongest argument is not "your skin will feel better." It prevents hardness minerals from taxing nearly everything in the house that uses water.
The biggest savings buckets are:
Less detergent.
Controlled WQRF-funded testing found that softened water could achieve equal or better laundry performance using 50% less detergent, and dishwasher detergent savings reached nearly 70% in very hard water.
Lower water-heating costs.
Calcium scale coats heating surfaces and acts as an insulator. The USGS specifically notes that scale can raise water-heating costs and reduce electric water-heater efficiency. The Battelle/WQRF testing found substantial efficiency losses as scale accumulated in hard-water equipment.
Longer life for water heaters and appliances.
Scale attacks water heaters, tankless heaters, dishwashers, washing machines, coffee makers and other water-using equipment. WQRF's research found equipment receiving softened water remained substantially freer of scale.
Fewer plumbing and fixture problems.
Hard-water scale accumulates on faucet aerators, showerheads, valves and other small passages. In Battelle's accelerated testing, hard-water showerheads lost substantial flow and faucet strainers clogged rapidly, while those receiving softened water performed much better.
Less cleaning expense.
Softened water means less mineral film on shower glass, faucets, sinks, tubs and toilets, so homeowners generally need fewer scale removers and cleaning products. WQRF identifies scale deposits and higher soap consumption as common costs of hard water.
A water softener isn't simply another appliance. It's an appliance that protects virtually every other water-using appliance in your home.
Think about a $3,000 tankless water heater, $1,000 dishwasher, $1,200 washing machine, expensive faucets, shower valves, coffee maker, and plumbing system.
$3,000
tankless water heater
$1,200
washing machine
$1,000
dishwasher
Hard water doesn't send you one big bill. It sends you lots of little bills.
- More detergent.
- More energy.
- More cleaning products.
- More descaling.
- More service calls.
- Premature appliance repairs and replacement.
So, a properly sized softener does more than solve one problem. It helps protect the entire home from the hidden costs of hard water. If we were to never build a new home without an air conditioner, why are we still building homes without conditioned water?
Shop Whole-Home Water Conditioning
How US Water Systems Conditions the Whole Home
At US Water Systems, we take a comprehensive approach to water treatment for the modern home. Let's look at a couple of common systems that we frequently provide our customers with for city water.
Which of the two is the starting point for you?
Pick the line that sounds like your house. Both complete configurations are laid out in full below either way.
Start with Option 1.
Four stages: a 5 micron Magna Filter, a water softener, ultraviolet disinfection, and reverse osmosis for drinking water. Read the full sequence immediately below.
Look at Option 2.
Option 2 adds an upflow, non-electric carbon filter ahead of everything else, which removes chemicals that can ordinarily be absorbed through the skin, such as chlorine and chloramine, as well as odors. It is what many consumers are now opting for. Read both sequences below, in order.
Get the hardness number first.
Hardness is the number that decides everything downstream. If you are on city water, your utility publishes a Consumer Confidence Report. For the full picture, including the alkalinity and ionic composition that decide how a conditioner behaves above 10.5 gpg, get a laboratory water analysis, then have the system sized rather than guessed.
Option 1: Pre-Filter, Water Softener, Ultraviolet Disinfection, and Reverse Osmosis for Drinking Water
5 Micron Magna Filter
Filters out large sand, silt, sediment, rocks, fish, and turtles… OK, I just made those last two up.
Made in AmericaWater Softener
Fully automatic, on-demand.
Made in AmericaUltraviolet Disinfection
Guarantees bacterially pure water throughout your home… or you can trust the city to do that.
Reverse Osmosis Drinking Water System
RO removes the widest spectrum of contaminants of any water treatment process, including arsenic, nitrate, PFAS, chlorine, chloramine, sodium, and a plethora of chemicals.
Made in America
However, today, many consumers are now opting for this system:
Option 2: Carbon Filter Pre-Filter, Sediment Pre-Filter, Water Softener, Ultraviolet Disinfection, and Reverse Osmosis for Drinking Water
Upflow, Non-Electric Carbon Filter
Removes chemicals that can ordinarily be absorbed through the skin, such as chlorine and chloramine, as well as odors.
5 Micron Magna Filter
Filters out large sand, silt, sediment, rocks, fish, and turtles… OK, I just made those last two up.
Made in AmericaWater Softener
Fully automatic, on-demand.
Made in AmericaUltraviolet Disinfection
Guarantees bacterially pure water throughout your home… or you can trust the city to do that.
Reverse Osmosis Drinking Water System
RO removes the widest spectrum of contaminants of any water treatment process, including arsenic, nitrate, PFAS, chlorine, chloramine, sodium, and numerous other chemicals.
Made in America
If you are on municipal water, you don't have to guess what is in your water. At US Water Systems, we can tell you. Let us size a system for you. We have more Certified Water Specialists on staff than anyone else. We are America's Water Company for a reason!
Your Next Steps
Step 1: Find Out How Hard Your Water Actually Is
Hardness is the number that decides everything downstream, including whether a salt-free conditioner is even a candidate. If you are on city water, your utility publishes a Consumer Confidence Report. If you want the full picture, including alkalinity and the ionic composition that determine how a conditioner behaves above 10.5 gpg, get a laboratory water analysis.
Step 2: Decide Between Option 1 and Option 2
Option 1 is the four-stage configuration: pre-filter, softener, UV, and reverse osmosis for drinking water. Option 2 adds an upflow, non-electric carbon filter ahead of everything else, which is what most consumers on chlorinated or chloraminated city water are now choosing.
Step 3: Have It Sized, Not Guessed
A properly sized softener protects the tankless heater, the dishwasher, the washing machine and every fixture in the house. An undersized one does not. Let our Certified Water Specialists size the system to your hardness, your flow rate and your household, the same way a builder sizes the HVAC before anyone moves in.
Get Expert Water Guidance
Our Certified Water Specialists will help you understand what's in your water and design a solution tailored to your home, no guesswork required.
Talk to a Water ExpertFrequently Asked Questions (FAQs)
-
Q: My builder installed a great HVAC system. Doesn't that mean the water is handled too?
A: No. The Census Survey of Construction tracks heating type and central A/C, but it does not track water softeners at all, and there is no reliable national statistic on new homes completed with one installed. Air and water are conditioned by two completely separate systems, and only one of them is close to standard equipment.
-
Q: Will a salt-free conditioner do the same job as a softener?
A: It is not the same thing, which is why we have never called ours a softener. Salt-free conditioners work best between roughly 3.5 and 10.5 gpg, and depending on alkalinity, Langelier Index and ionic composition they may work somewhat above that. If a company claims theirs works at 81 gpg, get that guarantee in writing.
-
Q: Is a softener really worth it if my water only feels a little hard?
A: Hard water does not send one big bill, it sends lots of little ones: more detergent, more energy, more cleaning products, more descaling, more service calls and earlier appliance replacement. WQRF-funded testing found softened water matched or beat laundry performance on 50% less detergent, with dishwasher detergent savings near 70% in very hard water.
If you are ready to condition your water the way your builder conditioned your air, US Water Systems can test it, size it and build the system around what your water actually contains.