Hard water and water softeners: do you need one, and what to know before buying
Updated · KeystoneProGuide editorial team
What is hard water?
Water with a lot of dissolved calcium and magnesium. Penn State Extension says those two minerals have no adverse health effects and are in fact essential nutrients, but that when water carries enough of them they build up on surfaces, can plug pipes and damage water heaters, and make soap and detergent less effective. The signs it describes are white or gray scale when water is heated, soap that does not lather well, and film on fixtures and washed clothes.
How hard is too hard?
Penn State gives a scale in grains per gallon, the unit most water reports use, alongside milligrams per liter:
| Classification | Grains per gallon | Milligrams per liter |
|---|---|---|
| Soft | Less than 1.0 | Less than 17 |
| Slightly hard | 1.0 to 3.5 | 17 to 60 |
| Moderately hard | 3.5 to 7.0 | 60 to 120 |
| Hard | 7.0 to 10.5 | 120 to 180 |
| Very hard | More than 10.5 | More than 180 |
Its rule of thumb is that water below 7.0 grains per gallon will probably not cause major scaling and soap film.
Do you need a water softener?
Penn State's answer is that it is a preference, not a necessity. Softening removes hardness minerals and the nuisances they cause; it does not purify water. The extension says the idea that softening is a purifying or cleansing process has spread largely through exaggerated advertising, and that softeners will not necessarily remove the more serious contamination problems. If your concern is health rather than scale, Penn State's advice is to have a certified lab identify the actual problem and its level first. For lead, for example, the EPA's advice is a filter certified to remove lead, not a softener.
The benefits Penn State does credit are less scale on cookware and fixtures, less soap film and detergent curd, more effective cleaning, and longer life for water heaters, which scale can shorten.
How does a softener work?
By ion exchange. Penn State explains that water passes through a bed of resin coated with sodium ions, which the resin trades for calcium and magnesium. When the resin is full of hardness minerals, the softener regenerates by flushing it with a salt brine and sending the minerals to the drain. Timed models regenerate on a schedule whether or not the resin needs it, wasting water and salt; demand-controlled models regenerate after a set volume of water, which suits households whose use varies.
What are the drawbacks?
Penn State lists three.
- Sodium. Softening adds 7.5 milligrams of sodium per quart for each grain per gallon removed, a concern for anyone on a low-sodium diet. It also removes the calcium and magnesium from the water you drink.
- Upkeep. Every softener needs maintenance: the brine tank kept supplied, and the resin kept clear of mud, iron, bacteria and fungi, sometimes with filtering or disinfection upstream. Read the maker's instructions before adding any cleaner.
- Septic load. Each regeneration uses about 50 gallons of water, which Penn State says may or may not overload a septic system's drainfield. The EPA's general septic advice is that the less water a household sends down its pipes, the better the system works.
Penn State also notes that a softener can easily bypass toilets and outdoor faucets, and that softened and unsoftened water can be blended to reach a lower hardness rather than removing it all.
What does a water softener cost?
Penn State puts the hardware alone at about $500 to $1,500, rising with convenience features. Angi gives $200 to $500 for water softener installation.
How do you avoid being oversold?
Test first, with someone who is not selling the equipment. Penn State says many softening companies offer free hardness testing but that a third-party test from an independent lab is not expensive and will protect you from buying more than you need. Its advice on water treatment in general is just as direct: do not rely on in-home tests by treatment vendors, use a certified lab, visit several vendors, compare prices, service and warranties, ask for references, and get everything in writing. It adds that, despite claims to the contrary, no single device removes every contaminant.
If you are on public water, your utility's annual Consumer Confidence Report, which the EPA requires by July 1 each year, is a place to start for what is in your water. If you have a private well, Penn State says hardness and iron are among the most common nuisance problems, and recommends annual coliform testing in any case.
Who installs a softener?
Angi lists water softener installation among the jobs plumbers price, and Penn State refers owners to their softener dealer for resin replacement. Either way, the usual checks apply: a local plumbing license where your municipality requires one, a written price, and a permit if your code office calls for one. Plumbing scams to avoid covers water treatment pitches, septic system homes covers the drainfield question, and plumbers are listed on the plumbers directory page.
Sources
- Water Softening, Penn State Extension
- Private Water Systems FAQs, Penn State Extension
- How Much Does Plumbing Repair Cost? [2026 Data], Angi
- Basic Information about Lead in Drinking Water, U.S. Environmental Protection Agency
- How to Care for Your Septic System, U.S. Environmental Protection Agency