Water Filter for the LG LFX31945ST (LT700P)

LFX31945ST specifics — where the filter actually lives

Finding the bay is the easy part — this chassis puts it top-left of the fresh-food compartment in most French-door layouts, away from the door bins, a deliberate placement that keeps the swap away from the door seals and drawer rails. The seat combines push-fit and twist-lock: seat the cartridge, give it the quarter turn, and the bay takes it from there.

Owners of the LFX31945ST report the same friction points: carbon fines in the first pours are normal for a fresh bed, and the filter timer only restarts when you hold the reset. The LF prefix is the tell: LF is LG’s own coding for French-door machines, and in that format the water path is long enough that a neglected cartridge shows up as flow drop before it shows up as taste. That ST suffix is trim-level shorthand. LG kept the LT700P bay common to every finish in the line.

LF vs LS — what the prefix tells you

Two prefixes, two missions: French-door against side-by-side, respectively. Filter bays rarely care — the media family carries over more often than not. Capacity check: the 31 cubic feet in the code is the box size, and bigger boxes push more water through the same cartridge between swaps.

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

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.

LFX31945ST filter questions