Water softener installation and whole-house filtration

Softener or filter — which do you need?

They solve different problems. A water softener removes hardness — calcium and magnesium — which leaves scale in kettles and water heaters, spots on glass and a film in the shower. A filter removes or reduces specific contaminants: chlorine taste and smell, sediment, lead, or chemicals such as PFAS, depending on the filter.

Hardness is a nuisance rather than a health issue. EPA’s WaterSense guide says some hardness “is generally not a health hazard” and that softeners “can be used to remove excessive hardness” (EPA). Plenty of homes with hard water and a contaminant concern end up with both: a filter and a softener on the same line.

Test your water first

Buy for what is in your water, not for what a salesperson says is in it. On a public supply, your utility’s annual Consumer Confidence Report lists what it tests for; on a private well, EPA advises periodic testing by a state-certified lab (EPA WaterSense).

Hardness is usually reported in milligrams per litre (mg/L) or grains per gallon. The US Geological Survey classes 0–60 mg/L as soft, 61–120 as moderately hard, 121–180 as hard and over 180 as very hard (USGS). One grain per gallon is about 17.1 mg/L.

Types of system

• Salt-based ion-exchange softeners swap calcium and magnesium for sodium (or potassium). They regenerate with salt and flush brine to a drain.
• Twin-tank softeners do the same with two tanks, so one is always in service.
• “Salt-free” conditioners change how minerals behave so they scale less; they do not remove hardness. Look for certification to IAPMO/ANSI Z601 if you go this way.
• Carbon and sediment filters, often whole-house, for chlorine taste and particles.
• UV systems, which disinfect against microorganisms (common on wells) but do not remove chemicals.
• Reverse osmosis, usually under one sink for drinking water.

Sizing a softener is arithmetic: your hardness in grains per gallon, times the gallons your household uses a day, sets the capacity it needs between regenerations. A pro should show you that calculation.

Whole-house water filtration

A whole-house (point-of-entry) filter treats every tap; an under-sink unit treats one. Whole-house carbon is the usual answer to chlorine taste and smell. For lead or PFAS, what matters is the certification for that contaminant, not the size of the system — and many people treat drinking water at one tap instead.

EPA’s guide notes that carbon filtration does not remove nitrates, bacteria or dissolved minerals (EPA WaterSense). If your test shows those, you need a different technology — and a well with bacteria needs its cause found as well as treated.

How to choose a water treatment pro

• Insist on a written water test result before a quote, and keep a copy.
• Ask which certification the system carries for the problem you have. EPA points to NSF/ANSI 44 for softeners, NSF/ANSI 42 for taste and odour, NSF/ANSI 53 for health contaminants, NSF/ANSI 58 for reverse osmosis and NSF/ANSI 55 for UV.
• Ask about regeneration. EPA advises demand-initiated regeneration, which regenerates by water use rather than on a timer and wastes less water and salt.
• Ask about local rules. EPA notes some jurisdictions restrict softeners because of the salt they discharge — check before you buy.
• Get the running costs in writing: salt, filter cartridges, membranes, and how often.
• Ask who does the plumbing. Installing a softener means cutting into the main line and adding a bypass and a drain; in many places that needs a licensed plumber.

What affects the cost

• Type and capacity of the system.
• Installation: how easy the main line is to reach, whether a drain and power outlet are close by, and any bypass or loop that needs adding.
• Water testing, if it is not included.
• Running costs: salt or potassium, filter changes, and service visits.
• Rent or buy. Some dealers rent systems monthly; compare the total over the years you expect to stay.

Water Softening cost guide: the factors pros price on →

DIY or pro?

Topping up salt, changing cartridges and bypassing the system for outside taps are owner jobs. The install itself means working on your main water line; if you are not comfortable soldering or fitting a bypass, or your area requires a permit, hire a licensed plumber or a dealer who uses one.

Common questions

Do I need a water softener or a water filter?

A softener if your problem is scale and hardness; a filter if it is a contaminant, taste or smell. A water test tells you which — and some homes need both.

Is hard water bad for your health?

EPA’s WaterSense guide says some hardness is generally not a health hazard. It is mainly a nuisance for plumbing, appliances and cleaning.

What size water softener do I need?

Multiply your hardness in grains per gallon by your household’s daily water use. That figure sets the capacity needed between regenerations; a good installer shows you the sum.

How long do water softeners last?

Sources disagree, and it depends on the unit, your hardness and maintenance. Ask the installer what the warranty covers and for how long — it is the most concrete answer you will get.

Do salt-free softeners actually soften water?

No. They condition minerals so they form less scale, but the hardness is still in the water. If you want soft water, you want an ion-exchange softener.

What certification should a water filter have?

The one for the contaminant you are treating. EPA points to NSF/ANSI 42 for taste and odour, 53 for health contaminants such as lead, 58 for reverse osmosis and 401 for emerging compounds.

Does a whole-house filter remove PFAS or lead?

Only if it is certified to reduce that contaminant. For PFAS, EPA advises checking the packaging for NSF/ANSI 53 or NSF/ANSI 58 certification (EPA); for lead, look for NSF/ANSI 53 certification that names lead.

Are water softeners banned where I live?

Some local jurisdictions restrict them because of the salt they discharge, EPA notes. Check with your city or water utility before buying.

Sources

Safety and standards advice on this page comes from these publishers. Dates are the ones each page shows.

• US EPA WaterSense, Guide to Selecting Water Treatment Systems (November 2024)
• US Geological Survey, Hardness of Water (August 24, 2026)
• US EPA, Reducing PFAS in Your Drinking Water with a Home Filter (April 2024)