Water Softeners and Filters

What is the difference between a softener and a filter?

A water softener deals with hardness, which comes from dissolved minerals such as calcium and magnesium. It trades those minerals for another ion, so scale builds up less in pipes, water heaters and fixtures. It is not designed to catch dirt, bacteria or most chemicals.

A filter, by contrast, physically or chemically catches certain things as water passes through. Different filters target different items, such as sand and rust particles, tastes and odors, or specific substances. Neither device is a general purpose cleaner, and neither replaces a lab test.

How do I know whether I need a softener?

Signs of hard water include scale on faucets and kettles, spotted dishes, soap that does not lather well and a water heater that wears out sooner than expected. A lab test or a simple local test can confirm hardness and show whether iron or manganese are also present, which affects equipment choice.

Softening is mostly about comfort, appliance life and cleaning. It is not normally a health requirement. If anyone in the household is on a low sodium diet, ask a doctor about water treated by a softener, since the process adds sodium or potassium depending on the supplies used.

Also ask about how wastewater from a softener affects your septic system. Recommendations differ by system and by local rules, so your county health office or a septic professional is the right source.

• Scale on fixtures and kettles
• Dry feeling skin and hair after washing, for some people
• Soap that is hard to rinse
• Short life for water heaters

What kinds of filters are common?

Sediment filters catch sand, silt and rust. Carbon filters can reduce some tastes, odors and chemicals. Iron filters handle dissolved iron in specific ways. Specialty cartridges target named substances, and some are meant only for a single tap.

The label should state what the filter has been independently tested to reduce. If it does not, treat the claim cautiously. A filter that is overdue for replacement can stop working, and in some cases can become a place where microorganisms grow.

Remember that point of use filters under the sink often handle only the kitchen tap. If you want treated water for the whole house, ask a professional whether a whole house unit and a drinking water unit together make sense.

How much upkeep do they need?

Softeners need salt or a similar supply and occasional cleaning of the brine tank. They also need periodic checks that the settings still match your water. Filters need cartridges replaced on schedule, and pressure can drop as they clog.

Put the replacement date on a calendar when you install anything. Keep the manual, model number and the name of a local service contact. Many problems come from a unit forgotten under the stairs for years.

• Check salt level on a regular basis
• Replace cartridges on the maker's schedule
• Watch for pressure drops after a filter change
• Keep service records

What if the water is also unsafe to drink?

Softeners and general filters do not make unsafe water safe. If a test shows bacteria, nitrate or another health concern, the answer starts with advice from your county health department, then a suitable treatment designed for that substance.

In the meantime, ask what to use for drinking and cooking. Do not assume equipment already in the house is handling the problem. Test the treated water, not only the water before treatment, to see what actually reaches your tap.

How do I choose a vendor or installer?

Get an independent lab report first, then ask more than one local professional for a written proposal. Compare what each says it will treat, the equipment specifications, installation, yearly cost and warranty.

Be wary of high pressure sales or claims that a single machine fixes every problem. Your cooperative extension office and health department can give unbiased background before you talk to anyone selling equipment.

What are the common mistakes?

The most common mistake is buying equipment before testing. A second is expecting one device to do everything. A third is skipping maintenance, which turns a helpful unit into a source of trouble. Some owners also install treatment ahead of a problem that is actually in the plumbing, such as a corroded line or a failing water heater.

Another mistake is forgetting that equipment needs power and sometimes a drain. Think about where the discharge goes, whether the room stays above freezing and whether you can reach the unit for service. A tidy plan on paper prevents a hard installation later.

If you are renting, ask the landlord before changing anything, since equipment and plumbing changes may need permission.

Last reviewed: November 12, 2026. Written by the Rural Farm Life Editorial Team. See our editorial policy.