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Water Filter for the LG LFX25978ST (LT700P)
✓ 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:
✓
LFX25978ST specifics — where the filter actually lives
Where the filter actually lives: upper rear of the fresh-food section in most French-door builds with interior dispensers, a deliberate placement that keeps the swap away from the door seals and drawer rails. Mechanically it is a push-and-twist seat: seat first, rotate second — reversing the order is the only way to fight this bay, and it will not let you.
Two quirks worth knowing before you order: a stubborn first twist when the old o-ring has set, and a change-filter light that will not clear itself until you hold the reset. Read the prefix and the maintenance writes itself: LF machines come from the French-door program, and LG’s parts system rewards you for knowing it: one cartridge family covers the run. The ST tail marks finish variants of one chassis; the filter bay is shared across the entire finish range.
LF vs LS — what the prefix tells you
Same parts shelf, two cabinet missions — LF answers to French-door; LS answers to side-by-side; the water-filter answer is shared. capacity 25 cubic feet: a mid-to-full-size cabinet whose dispenser traffic sets the realistic change cadence.
Swap it in 5 minutes
- Press the release (if fitted), twist the old cartridge free, and pull it from the header.
- Wet the new cartridge’s o-ring with cold tap water so it seats without dragging.
- Push the cartridge square onto the header, then give it the locking quarter turn.
- 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.
LFX25978ST filter questions
Clearing the filter status light on a LG LFX25978ST?
Lock in the new cartridge first, then hold the reset control for a few seconds — the LFX25978ST manual documents the button for each panel variant.
Is a bypass plug required for the LFX25978ST when the cartridge is removed?
No bypass needed: the LT700P bay closes on its own, and running empty simply means the water skips filtration until you seat a new cartridge.
Are off-brand filters safe for a LG 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 LT700P 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 LFX25978ST?
Every six months or at the rated gallon capacity, whichever comes first — the LT700P 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 LT700P. 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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