Water Filtration Maintenance: A Simple Schedule for Every System

A water filter is only as good as its last cartridge change. Once a filter is full, it can't catch more. A clogged sediment filter chokes water pressure. A spent carbon filter lets chlorine taste come back. And the CDC warns that you need to maintain any filter "to keep it working properly and prevent germs from growing in it" (CDC).

This guide gives you one schedule for every common home system. It also shows how to change a whole house filter, what maintenance costs, and when a professional water filtration service is worth it.

Water filtration maintenance schedule at a glance

These are typical intervals drawn from manufacturer instructions and public health guidance. Your system's manual may say something different. When it does, follow the manual.

Sources: Aquasana, iSpring, Connecticut DPH, HomeGuide, UNL Extension, CDC.

Maintenance by system type

Whole house filters (point of entry)

Most whole house setups use two or three stages. A sediment filter comes first, then carbon, sometimes followed by a fine post-filter.

Sediment pre-filter. This is the part you'll change most. It catches sand, silt, and rust before they reach the carbon. Aquasana, for example, tells owners of its 20-inch pre-filter to "replace every 2 months" and sooner if flow drops (Aquasana). Well water with lots of sediment may need even faster changes.

Carbon cartridge or tank. Carbon reduces chlorine, taste, and odor. Cartridge systems usually need a new carbon filter every 6 to 12 months. Large tank systems are often rated by total gallons, so check your water meter or usage.

Tip: install pressure gauges. A gauge before and after the filter housing shows you when a cartridge is clogging. When the gap between the two readings grows noticeably compared with a fresh cartridge, it's time to change it. Many manufacturers list an exact pressure-drop trigger in the manual.

Under-sink and reverse osmosis systems

RO systems have several stages, and each wears out on its own schedule. iSpring's guidance for its RO systems is a useful example (iSpring):

• Stages 1–3 pre-filters: every 6–12 months, or sooner if flow slows
• RO membrane: every 2–3 years, or sooner if TDS starts rising
• Carbon post-filter: every 12 months
• UV lamp (if included): every 12 months

The pre-filters protect the membrane. Skipping them is the fastest way to ruin an expensive membrane.

Check TDS to know when the membrane is done. A handheld TDS meter compares the total dissolved solids in tap water and RO water. If the RO water reading creeps up over time, the membrane is losing performance. See our guide on how to use a TDS meter.

Don't forget the RO storage tank (if your system has one). Many manufacturers recommend checking its air pressure and sanitizing the system when you change the membrane. Follow your manual's steps.

UV disinfection systems

UV lights are common on well water. They only work if the light reaches the water. The Connecticut Department of Public Health says UV lamps "gradually lose effectiveness with use" and should be cleaned regularly and replaced at least once a year (CT DPH).

The same publication recommends:

• Keeping the quartz sleeve clean, because film blocks the light
• Disinfecting the whole plumbing system with chlorine after servicing the UV unit
• Testing treated water for coliform bacteria monthly for the first 6 months after installation
• Keeping a maintenance logbook

Don't turn a UV system off to "save" the lamp. It's designed to run continuously.

Water softeners

Softeners need less attention than filters, but they still need some:

• Salt: Check monthly. HomeGuide says the average softener uses 40 to 60 pounds of salt a month (HomeGuide).
• Salt bridges: Push a broom handle down each time you add salt.
• Brine valve and float: UNL Extension recommends cleaning and inspecting them at least once a year (UNL Extension).
• Brine tank cleaning: Every 1–5 years, depending on salt purity and water source.
• Resin: Can last 10+ years on city water but may need replacing in 5–10 years on well water with iron, according to HomeGuide.

If something goes wrong, see our water softener repair guide.

Private wells

Well owners are responsible for their own water safety. The CDC recommends testing well water at least once a year for total coliform bacteria, nitrates, total dissolved solids, and pH, and checking the well for mechanical problems every spring (CDC). Annual testing also tells you whether your treatment equipment is still doing its job. Read more about well water filtration systems.

How to change a whole house water filter

This is the most common maintenance job. It takes about 15 minutes.

You'll need: the correct replacement cartridge, the housing wrench, a bucket, a towel, food-grade silicone grease, and gloves.

1. Shut off the water. Close the valve before the filter, or switch to bypass if you have one.
2. Relieve pressure. Open a nearby faucet for a minute or two. Press the pressure-release button on the housing if it has one.
3. Remove the housing. Place the bucket underneath. Unscrew the housing with the wrench.
4. Swap the cartridge. Dump the old cartridge and water. Wash the inside of the housing with mild soapy water and rinse it.
5. Check the O-ring. Wipe it clean and coat it lightly with silicone grease. Aquasana's instructions specifically say not to use petroleum jelly (Aquasana).
6. Reassemble. Seat the new cartridge in the center. Screw the housing on hand-tight, then snug with the wrench. Don't overtighten.
7. Turn the water back on slowly. Check for drips. Run water for a few minutes to flush air and carbon fines.
8. Write down the date. A label on the housing works great.

Health tip: The CDC advises wearing gloves when changing filters and washing your hands afterward. If you have a weakened immune system, the CDC suggests you avoid changing filters yourself (CDC).

Monthly, quarterly, and yearly checklist

Every month

• Check softener salt and look for bridges
• Glance at filter pressure gauges
• Look for drips at housings and fittings

Every 2–6 months

• Replace sediment pre-filters (or per manual)
• Check RO flow rate and taste

Every 6–12 months

• Replace carbon cartridges and RO pre-filters
• Test RO water with a TDS meter
• Replace UV lamp (yearly) and clean the quartz sleeve
• Inspect softener brine valve and float
• Test well water (coliform, nitrate, TDS, pH)

Every 2–3 years

• Replace RO membrane (or when TDS rises)
• Clean the softener brine tank

A note on whole house carbon and chlorine

Whole house carbon filters remove chlorine from all your water. That's often the goal. But the CDC notes a trade-off: if a whole-home filter removes chlorine or other disinfectants, "more germs may grow in your plumbing" (CDC). This is one more reason to change cartridges on time, flush lines after long trips, and keep housings clean.

What water filtration maintenance costs

Sources: Angi (filters, upkeep, pro maintenance), HomeGuide (softener service).

Planning a new system? Factor these yearly costs in. Our guides to whole house water filtration system cost and water softener cost include running costs.

DIY or professional water filtration service?

Most homeowners can handle cartridge swaps, salt, and TDS checks. A professional water filtration service makes more sense when:

• You have a multi-stage well system with UV, iron filters, or chemical feed
• A control valve or backwashing filter isn't cycling correctly
• You need plumbing changes, like adding a bypass or gauges
• You're immunocompromised (per the CDC tip above)
• Your warranty requires professional service

Ask any service company what's included, whether filters are priced separately, and whether they test water before and after.

Seasonal and special-situation maintenance

Some jobs aren't on a calendar. They're triggered by events.

Before and after a long trip. Water that sits in filter housings and pipes for weeks can go stale. When you get home, run each tap for a few minutes. The Connecticut Department of Public Health notes that the plumbing system "should be thoroughly flushed following a period of no use," and that UV lamps need a few minutes to warm up after a shutdown (CT DPH).

Freezing weather. Filter housings and softener tanks in garages or crawl spaces can crack if they freeze. Insulate them, or keep the space above freezing. A cracked housing is a common repair that's easy to prevent.

After flooding or well work. The EPA recommends testing your private well right away if there's flooding nearby or if you repair or replace any part of the well system (EPA). If floodwater reached your well or treatment equipment, contact your local health department before drinking the water. Plan on replacing cartridges that may have been exposed, and follow your manufacturer's sanitizing steps.

After servicing a UV system. CT DPH advises disinfecting the entire plumbing system, such as with chlorine, before relying on UV again.

When your water changes. A new taste, smell, color, or stain is a signal. The CDC suggests testing well water if you notice changes in color, taste, or smell (CDC). City customers can check their utility's annual water quality report.

Keep a simple maintenance log

Connecticut's public health guidance recommends keeping a logbook for treatment equipment maintenance and repairs. It doesn't need to be fancy. A note on your phone or a card taped to the filter works.

Record these for each system:

After a few cycles, your log tells you the real interval for your water. That may be shorter or longer than the manual's general advice.

Signs your filter needs attention now

Don't wait for the calendar if you notice:

• Lower water pressure at every faucet
• Chlorine or "pool" smell returning
• Cloudy, discolored, or gritty water
• A UV alarm or warning light
• Higher TDS readings from your RO tap
• Hard water spots returning (softener issue)

FAQ

Sources

• CDC, About Choosing Home Water Filters
• CDC, Guidelines for Testing Well Water
• U.S. EPA, Protect Your Home's Water (private wells)
• iSpring, How often should I replace the cartridges?
• Connecticut Department of Public Health, Ultraviolet Radiation Treatment of Private Drinking Water Systems
• Aquasana, Whole House Pre-filter Cartridge Replacement
• Angi, How Much Does a Water Treatment System Cost?
• HomeGuide, Water Softener Repair, Service, or Maintenance Cost (updated Jul 2025)
• University of Nebraska–Lincoln Extension, Water Softening (Ion Exchange), G1491

This schedule is compiled from manufacturer instructions, public health agencies, and national cost data. It is not a substitute for your system's manual. Filtiva has not hands-on tested the products mentioned.