Every six to twelve months for most whole-house filters, though it depends on the media type, your water’s sediment load, and household usage. Sediment cartridges typically need changing more often than carbon; a pressure drop across the system is the reliable signal.

Typical Intervals

  • Sediment cartridges: every 3–6 months, more often on well water or after nearby main work stirs up particulate
  • Carbon filters: every 6–12 months
  • Combination cartridges: generally 6–12 months
  • Large-tank backwashing media systems: media replacement measured in years rather than months

The Reliable Signal

A pressure drop. Install pressure gauges before and after the filter housing, and when the difference between them grows noticeably, the cartridge is loading up. This is far more accurate than a calendar, because it responds to your actual water rather than an assumption about it. Reduced flow at fixtures is the same signal without the gauges.

Other Signs It Is Overdue

  • Chlorine taste or smell returning, meaning carbon media is exhausted
  • Visible discoloration on the cartridge when you inspect it
  • Reduced water pressure throughout the house
  • Sediment appearing at fixtures again

Why Not Stretching It Matters

An exhausted carbon filter stops removing chlorine — it is not harmful, it is simply doing nothing. A loaded sediment cartridge is worse: it restricts flow, which stresses everything upstream, and in extreme cases can channel or bypass, sending accumulated material downstream. Neither situation is catastrophic, but you are paying for a system that has stopped working.

What Extends Cartridge Life

A sediment pre-filter ahead of the carbon stage — the sediment cartridge is cheaper to replace and protects the more expensive carbon media from clogging with particulate.

Related Maintenance

If you have a softener downstream, the carbon filter is also protecting its resin from chlorine degradation — another reason not to let it lapse. And RO systems have their own separate cartridge and membrane schedule.

Care Club members get scheduled service. Contact B. Carlson about whole-house filtration.