Home Water Filter Replacement Schedule: When to Replace Every Filter Type

Sediment filters use mechanical filtration to trap particulate matter. Over time they clog and break down. Very high sediment loads, organics, or chemical contamination from wells or job sites or other environmental factors such as may necessitate weekly or even daily changes. Here are basic replacement schedules:

• Melt-blown polypropylene: Replace every 3–6 months for typical residential use. Clean municipal water may extend life to 9 months, while sediment-heavy well water could require monthly replacement.
• String-wound: Replace every 3–6 months. Can handle limited washing for reuse in high-sediment applications, though filtration efficiency decreases with each cleaning.
• Pleated polyester: Replace every 3–6 months. Can be carefully rinsed once or twice to extend life. The pleated design offers high surface area and dirt-holding capacity.
• Bag filters: Replace every 1–6 months depending on size and application. Monitor pressure drop and flow rate to determine replacement timing.

Watch for decreased water pressure at fixtures as your primary signal that sediment filters need replacement. Visible dirt accumulation and red or brown discoloring also indicate it's time for a change.

Carbon filters use molecular-level chemical adsorption to trap and remove chlorine, chemicals, and contaminants affecting taste and odor. While some carbon media can be backwashed to reduce sediment buildup and extend the physical life of the filter, backwashing does not restore the carbon's adsorption properties. Eventually, the carbon will be exhausted. Such is the life of most carbon media. Here's when to change carbon filters:

• Granular activated carbon (GAC): Replace every 6–12 months depending on cartridge size and water quality. Typically rated at 20–25 microns, GAC excels at chlorine reduction and taste improvement.
• Carbon block: Replace every 6–12 months depending on cartridge size and water quality. Also known as bonded PAC (powdered activated carbon), carbon block filters offer 0.5–10 micron filtration. Lower micron filters will require more frequent replacement if also capturing sediment.
• Catalytic carbon: Replace every 6–12 months depending on cartridge size and water quality. These specialized filters target chloramines and hydrogen sulfide more effectively than standard GAC.
• Carbon-impregnated polyester: Replace every 3–6 months. Sometimes grouped with sediment filters, these dual-purpose cartridges combine mechanical sediment removal with chemical adsorption.

While 6 months is often a reasonable baseline recommendation, carbon may need more frequent replacement based on pre-filtration, usage, and overall quality.

Different applications require specialized replacement schedules based on usage patterns and filter design:

• Refrigerator filters: Replace fridge filters every 6 months or when your indicator light signals replacement. Signs include decreased water flow, bad taste or odor, reduced ice production, or visible particles. For more information on when to change and how to troubleshoot refrigerator filters, read our story.
• RV inline filters: Replace once per camping season, or within 3–4 months once wet. Full-time RVers should expect more frequent RV filter replacement. Dry completely between trips and store in a refrigerator during extended non-use to prevent mold.
• Descaler cartridges: Replace every 6–12 months depending on cartridge size and water quality. These polyphosphate filters prevent scale formation without electricity or salt.

Reverse osmosis systems require coordinated filter replacement to protect the semi-permeable membrane. The membrane removes dissolved contaminants through 0.0001 micron pores—far tighter than sediment and carbon pre-filters. While many users prefer an easy annual replacement cycle, here's the maintenance schedule:

• Sediment pre-filter: Replace every 6–12 months to protect the RO membrane from particulate damage
• Carbon pre-filter: Replace every 6–12 months to remove chlorine that would degrade the membrane
• Post-filter (polishing filter): Replace every 6–12 months for final taste improvement
• RO membrane: Replace every 2–3 years with proper pre-filtration and storage when the system isn't used for long periods of time.

RO membranes can be flushed following system directions to help extend service life. This process is automated on tankless models with booster pumps and straightforward on traditional tank-based systems. Regular pre-filter replacement is the best way to maximize membrane lifespan.

How often should I change my water filter?

Replacement frequency depends on filter type, water quality, and usage. Sediment filters typically need replacement every 3–6 months, carbon filters every 6–12 months, refrigerator filters every 6 months, and RO membranes every 2–3 years. Heavy sediment loads, poor water quality, or high usage require more frequent changes.

What happens if I don't replace my filter on time?

Exhausted filters reduce water flow, allow contaminants to pass through untreated, and in some cases can release trapped impurities back into your water. Old filters also strain pumps and appliances, potentially causing damage. Sediment filters clog and restrict flow, while carbon filters lose chemical adsorption capacity even when they appear clean.

Can I wash and reuse water filters?

Some filters allow limited washing. Pleated polyester sediment filters can be carefully rinsed once or twice to extend life, and string-wound filters tolerate limited washing in high-sediment applications, though efficiency decreases with each cleaning. Most carbon filters, refrigerator filters, and RO membranes cannot be effectively cleaned and must be replaced. When in doubt, replace rather than attempt cleaning.

How do I know when my water filter needs replacing?

Watch for decreased water pressure or flow rate, return of chlorine taste or odor, visible sediment in filtered water, or your refrigerator's filter indicator light. Some whole-house systems benefit from pressure gauges that show when filters are clogging. Don't wait for problems—establish a replacement schedule based on your water quality and stick to it.

How do I set a water filter replacement schedule?

Start by noting your installation date and the recommended replacement interval for each filter type. Request email reminders from your filter supplier—All Filters offers automatic notifications at checkout. Alternatively, set phone calendar reminders for each filter's replacement date, or use a traditional wall calendar to track maintenance. For multi-stage systems, consider replacing all filters on the same annual schedule for simplicity, even if some could last longer.