LG ThinQ water filter replacement: which cartridge fits

If you searched for an LG ThinQ water filter replacement and ended up here, the short answer is that ThinQ does not name a cartridge. ThinQ is LG's smart-home platform: it is the app that reports filter life, not the part number stamped on the housing. Two refrigerators sold as "LG ThinQ" can take completely different cartridges, and two refrigerators with no ThinQ badge at all can take the same one.

The four LG housings that cover almost every model

LG has used a small number of filter housings for more than a decade. The cartridge is determined by the housing, and the housing is determined by the model number.

• LT1000P — the ADQ747935 family. Most LG French-door and side-by-side models from roughly 2017 onward. Also sold as LT1000PC, LT1000PCS, ADQ74793501, ADQ74793502, MDJ64844601 and Kenmore 46-9980.
• LT700P — the ADQ36006101 family. Older French-door and side-by-side models, still very common. Also sold as LT700PC, ADQ36006102 and Kenmore 46-9690.
• LT800P — the ADQ73613401 family. Fits a narrower set of French-door models.
• LT600P and LT500P — the 5231JA2006 and 5231JA2002 families, used on older bottom-freezer and side-by-side models.

If your refrigerator is a ThinQ model and you do not know which of these it takes, the model number decides it. Look up your LG model and the site will name the cartridge, the housing location and the reset procedure.

How to confirm in two minutes

Open the fresh-food compartment and look for the sticker with the model and serial number — usually on the left interior wall or the ceiling. The model code is the part that starts with LF, LM, LS or LRF. Failing that, pull the cartridge that is in the housing now: the part number is printed on its face, and that number is the definitive answer.

What the ThinQ app is actually telling you

The filter-life percentage in the ThinQ app is a timer, not a sensor. It counts down from the day the filter was installed or the light was last reset, and it will happily report 40 percent left on a cartridge that has been sitting in a vacation house with no water drawn through it. LG rates these cartridges at six months or 200 to 300 gallons, whichever comes first, and the gallon figure is the one that matters in a busy kitchen.

Should you buy the genuine LG cartridge or an aftermarket one?

Both fit the same housing. The genuine part carries the full certification set for that housing, and on chip-equipped models it is recognised by the control board without argument. Certified aftermarket cartridges — Waterdrop, Glacier Fresh and similar — typically cost a third to a half as much and are certified to NSF/ANSI 42, sometimes 53, but rarely 401. If lead or pharmaceutical reduction matters to you, check the certification list on the specific part before ordering rather than assuming it matches the original.

The filter light will not reset after the change

That is the most common ThinQ complaint and it is almost never a bad cartridge. The board needs the filter-life counter cleared manually: press and hold the Water Filter button for about three seconds, or use the reset entry in the settings menu on models without a dedicated button. Step-by-step reset instructions cover the button layouts by model family.