Filter cartridge replacement: the job, the schedule, the cost

Advertised prices, verified

How to replace a filter cartridge without leaks

1. Shut off and relieve the pressure. Close the inlet valve (and outlet, if the housing has one), then press the housing's pressure-relief button or open a downstream tap until flow stops. Unscrewing a pressurized housing sprays water and can crack the sump, so this step is not optional.
2. Drop the sump and swap the element. Use the housing wrench, catch the water in a bucket, and lift out the old cartridge. Wipe the sump clean, check the new cartridge is the matching size and media, and seat it on the standpipe so it centers rather than leaning against the housing wall.
3. Service the o-ring before closing up. The o-ring causes most post-swap leaks: remove it, wipe the groove, apply a light film of food-grade silicone grease, and reseat it flat. Hand-tighten the sump plus a small turn with the wrench; overtightening distorts the seal it is meant to protect.
4. Repressurize slowly and flush. Open the inlet gradually with a downstream tap open to purge air, check for weeping around the sump, and flush new carbon until any gray fines clear. Write the date on the housing so the next replacement is triggered by the calendar, not by a bad taste.

Getting the schedule right

Media sets the interval: sediment cartridges are done when pressure drop says so, carbon is done when its capacity is spent whether or not anything tastes different, and RO membranes run on years rather than months. The maker's rated interval is the starting point, shortened when your water is heavily loaded and never lengthened on the argument that the water still tastes fine.

Cost-wise, the cartridge stream outspends the housing over any system's life, which is why the vendor prices in the table above matter more than the sticker on the original unit. Buying compatible elements for standard housings trims the bill, and our replacement water filter cartridges page covers how to match size, media, and micron rating before ordering.

Common questions

How do I know when filter cartridge replacement is due?

By the calendar and the pressure gauge, not by taste: exhausted carbon gives no flavor warning, while a loaded sediment cartridge shows up as falling flow. Date the housing at every swap and follow the maker's interval.

Why does my filter housing leak after a cartridge change?

Almost always the o-ring: pinched during reassembly, dried out, or seated over grit in the groove. Clean the groove, grease the ring lightly with food-grade silicone, and hand-tighten the sump instead of cranking on the wrench.

What does a year of filter cartridge replacement cost?

Multiply your system's cartridge count by its change frequency and price it from the table above, where the median runs $1,531. Single-stage housings cost little to feed; multi-stage systems multiply every line of that math.

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