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Water Filter for the GE ZIS420NMB (MWF)
✓ 100% compatible — no bypass plug needed
🔧 5-min push-in swap
🇺🇸 Ships from Indiana
Every cartridge that fits this model — pulled live from the catalogue:
✓
ZIS420NMB specifics — where the filter actually lives
Finding the bay is the easy part — this chassis puts it in the lower fresh-food zone in most side-by-side layouts, knee height or below, a deliberate placement that keeps the swap away from the door seals and drawer rails. It is a twist-lock bay: half a turn of wrist work in each direction is the whole procedure; everything else is towel management.
The recurring owner notes: the change light ignores the new cartridge until you reset it, and the first removal always takes more muscle than the manual implies. Read the prefix and the maintenance writes itself: ZIS machines come from the Monogram built-in side-by-side program, and GE’s parts system rewards you for knowing it: one cartridge family covers the run. Finish codes such as MB change the look, not the plumbing — order the cartridge by model, ignore the finish letter.
ZIS vs PSS — what the prefix tells you
The ZIS prefix sits next to PSS in the catalog and the split is cabinet mission: Monogram built-in side-by-side builds carry ZIS; Profile side-by-side builds carry PSS. Filter-wise the two lines converge on one cartridge family. Cabinet decode: 42 cubic feet — the number that tells you whether this cartridge feeds a family-size dispenser or a compact one.
Swap it in 5 minutes
- Twist the old cartridge a quarter turn counterclockwise and pull it straight down — keep a towel in reach for the dribble.
- Fill the new cartridge with cold tap water so the chamber is not fighting an air pocket.
- Offer the new cartridge to the bay, push up, and twist a quarter turn clockwise until the stop catches.
- Run two gallons through the dispenser to flush carbon fines, then hold the filter-reset control until the status light clears.
What this filter takes out of your water
| What it targets | Standard that covers it |
|---|---|
| Chlorine taste & odor | NSF/ANSI 42 — aesthetic effects |
| Particulates, Class I | NSF/ANSI 42 — fine sediment |
| Lead | NSF/ANSI 53 — health effects |
| Cysts (cryptosporidium, giardia) | NSF/ANSI 53 — microbial |
| PFOA & PFOS | NSF/ANSI 53 (P473) — varies by cartridge |
Coverage above lists what the standard addresses, not a performance claim for any specific cartridge — removal claims vary by certificate, so check the NSF listing for the exact part number you are buying.
ZIS420NMB filter questions
Clearing the filter status light on a GE ZIS420NMB?
Hold the filter-reset control a few seconds after seating the new cartridge; placements vary by control panel, and the ZIS420NMB manual’s filter-status page has the exact spot.
Running the ZIS420NMB with an empty filter bay — does it need a cap?
You can, but unfiltered — the MWF bay needs no bypass plug; it just passes water through without filtering while the cartridge is out.
Are off-brand filters safe for a GE refrigerator?
Certified aftermarket cartridges are built to the same NSF test standards as the OEM part, and federal warranty law (Magnuson-Moss) protects your coverage when you use them.
Why is the OEM MWF cartridge so much more expensive?
Part of the OEM price is the badge and the distribution chain. Certified alternatives meet the same test standards at a lower unit price, especially in multi-packs.
How often should I replace the filter in my ZIS420NMB?
Every six months or at the rated gallon capacity, whichever comes first — the MWF class cartridges all share that service interval.
Do I need to turn off the water supply to change it?
No — the bay is designed for a live swap. Expect a small dribble, keep a towel in reach, and flush a couple of gallons through the new cartridge before the first glass.
Every filter that fits your fridge
This bay takes the OEM MWF. ClearFit verified-fit alternatives for this exact slot are being staged — every compatible option for your fridge is one lookup away.
Check every filter that fits →This filter expires six months from today
Your HVAC filter is probably on a different cycle. Track them all in one place.
months until this filter should be replaced (200-gal rated life)
Free tool · tracks fridge + HVAC + whole-house · auto-refill optional
More models using this filter
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