A water filter you don’t maintain is a false sense of security. Clogged cartridges pass water around the media instead of through it. Old carbon releases trapped contaminants back into your water. Here’s how to keep every filter in your system working properly.
The Dirty Truth About Filter Maintenance
We opened up a 2-year-old pitcher filter from a family member who “replaced the cartridge when the light told them to.” The filter media was black with biofilm. Replacement was 8 months overdue.
Filters don’t just stop working — they can become net negative. Saturated carbon releases contaminants. Bacteria colonize old filter media. A maintained filter saves you. An unmaintained one betrays you.
Maintenance Schedule by Filter Type
Pitcher Filters (Brita, Pur, etc.)
- Replace cartridge every 2 months (40 gallons) or per indicator
- Rinse the pitcher with soap and warm water weekly
- Store in the refrigerator to slow bacterial growth
- Never let a wet cartridge sit idle — mold
Faucet-Mounted Filters
- Replace cartridge every 2-3 months (100-200 gallons)
- Check O-ring seal periodically — leaks defeat the purpose
- Sanitize the mounting hardware monthly
Under-Sink Filters
- Stage 1 (sediment): every 6 months
- Stage 2 (carbon): every 6-12 months
- Stage 3 (specialty): per manufacturer spec
- Check for leaks quarterly — under-sink leaks cause real damage
Gravity Filters (Berkey, Alexapure, etc.)
- Clean the chamber with mild soap and water monthly
- Scrub the filter elements with a Scotch-Brite pad when flow slows (don’t use soap on elements)
- Replace Black Berkey elements every 6,000 gallons per pair
- PFAS filters: replace every 1,000 gallons or annually
- Prime new elements properly — follow manufacturer instructions exactly
Reverse Osmosis
- Sediment prefilter: every 6 months
- Carbon prefilter: every 6-12 months
- RO membrane: every 2-3 years
- Post-filter carbon: every 12 months
- Sanitize the system annually with hydrogen peroxide or mild bleach solution
- Check TDS levels monthly with a TDS meter — rising TDS = failing membrane
The Rotation Rule
Buy replacement cartridges in bulk and store them sealed. A year’s supply of pitcher filters costs $30-40. During a supply chain disruption, you can’t overstock.
Label your installation dates. Set calendar reminders. Your filter can’t remind itself.