How to Replace an LG Refrigerator Water Filter (LT500P, LT700P, LT800P & Legacy Models)

Replacing a legacy LG water filter — the LT500P, LT700P, and LT800P families that predate the current LT1000P standard — is the same twist-and-turn job as modern LGs: open the housing cover, twist the old cartridge counterclockwise until it releases, pull it out, seat and clockwise-lock the new cartridge, purge about two gallons, reset the indicator. The mechanics take three minutes; the part-number decisions around legacy models are where the real work sits, and that is what this page is for.

This is the companion to our main LG filter change guide, which covers current LT1000P models in full. The focus here is the installed base that guide does not dwell on: smaller-capacity cartridges whose real-world interval lands under six months, the Kenmore 795 cross-references that confuse parts searches, and the discontinued part numbers whose replacement path runs through supersessions and, sometimes, the used-appliance market.

The Legacy LG Cartridge Table

Reading the table correctly matters because the cartridges are not cross-fittable. The LT700P is deliberately shallower for slim-door housings; an LT1000P will not seat in an LT700P slot no matter how cooperative the twist feels at first.

The capacity math that shortens the six-month rule

The six-month interval is a calendar ceiling paired with a gallon rating, and smaller-capacity cartridges hit the gallon ceiling first. A compact household runs through a small-capacity cartridge’s rated gallons well before the calendar turns — and a family of four running the dispenser and ice maker hard can exhaust one in four months. The interval rule, with the arithmetic, is covered in how long a refrigerator filter lasts; the short version: when the cartridge’s rated gallons divide by your weekly usage and the answer is under 26 weeks, ignore the calendar and count gallons. Flow drop and returning chlorine taste are the two signals that the ceiling has been hit regardless of what any calendar says.

Kenmore 795: the Cross-Reference That Finds Your Filter

Sears never built a refrigerator. Kenmore 795-prefix models are LG-built, and their water cartridges are LT-family parts wearing Kenmore 46- part numbers:

Two practical consequences. First, if a Kenmore-branded search dead-ends or prices badly, search the LG number — the same cartridge usually lists cheaper under its manufacturer part number. Second, the cross-reference runs one direction: the Kenmore 46- part must be matched to the correct LG cartridge, not to “any Kenmore filter,” because Kenmore’s other prefixes are Whirlpool-built (106), Frigidaire-built (253), and GE-built (363) with completely different cartridges. The full prefix-decoding system is in our Kenmore filter guide.

A pattern from repair forums worth internalizing: “my Kenmore Elite filter won’t fit” threads are almost always prefix confusion — an owner bought a 46- number for the wrong manufacturing family. Thirty seconds with the model-number prefix beats an hour of forcing cartridges. Elite-specific coverage lives in our Kenmore Elite guide.

Replacement Steps (Legacy Twist Mechanism)

Identical mechanics across the legacy families, differing only in housing location — door interior on slim French-door models, upper-left fresh-food compartment on bottom-freezers, top grille on older side-by-sides:

1. Open the housing cover. Swing or lift, per the hinge style.
2. Twist the old cartridge counterclockwise until the lock releases, then pull straight out along the cartridge axis. Towel under the housing — an ounce or two comes along.
3. Prep the new cartridge: strip the packaging, verify both O-rings sit flat in their grooves.
4. Insert to the bottom of the housing and twist clockwise to the detent. A firm, definite stop. Anything mushy means misaligned notches — back out and realign rather than force.
5. Purge about two gallons through the dispenser; discard the first two ice batches. Sputter (air) and gray tint (carbon fines) are normal in the first gallon.

No supply-valve shutoff needed. Reset the indicator per your panel — the methods by panel generation are tabulated in the LG reset guide.

Discontinued and Superseded Part Numbers

Legacy LG ownership eventually meets a part number that retail has stopped stocking. The replacement path, in order of preference:

1. Check the supersession. LG’s internal numbering (ADQ…) has cycled generations — a discontinued retail number often has a direct successor under the ADQ line. Our main LG guide’s table carries the current mappings.
2. Buy the compatible. The LT500P/LT700P compatible market is mature precisely because the installed base is old and price-sensitive. Same two-tier certification reality: NSF 42 standard compatibles, 42+53 premium compatibles — the tier definitions are in NSF 42 vs 53.
3. Do not substitute across families. A “close fit” from a different LT number will either not lock or seep. The 2025 notch change on current-generation cartridges adds one more reason to match the family exactly — the compatibility note in the main guide explains the tank-slot version check.

Pricing Reality for Legacy Cartridges

Genuine legacy cartridges list in the $35-50 band, with multi-packs pushing per-cartridge cost into the $20s; compatibles run well below that. The legacy market skews price-sensitive for a structural reason — nobody wants to pay half the fridge’s resale value per year in cartridges on a 12-year-old appliance — and that is exactly the segment where an honest compatible with published certification wins the order. The legal and warranty context for that choice is covered in OEM vs aftermarket filters.

Troubleshooting Legacy Swaps

• Twist releases but cartridge will not withdraw: swollen O-rings bonded to the housing spud. Steady pull with a slight rocking rotation; if the head tears off, stop and follow the stuck-filter extraction sequence before reaching for pliers.
• Slow drip after replacement: O-ring fold or a cross-family “close fit.” Inspect, reseat, and verify the part number family before ordering again — full leak diagnosis in the leak guide.
• Weak flow after replacement: air in the reservoir. Hold the dispenser pad through two minutes of sputtering before diagnosing further.
• Indicator refuses to reset: cartridge short of the detent. Re-seat, then apply the panel method again.

Frequently Asked Questions

Are LT500P, LT700P, and LT1000P interchangeable? No. Each is sized for a different housing generation — the LT700P is deliberately shallower, and the LT1000P does not seat in older slots. Match the number on the old cartridge exactly.

How often do smaller LG cartridges actually need replacing? Whenever the rated gallon capacity or six months arrives first — and small-capacity cartridges hit their gallon ceiling early in busy households. Count gallons, not just calendar months; the method is in how long a filter lasts.

My Kenmore 795 fridge — which filter do I buy? An LT-family cartridge. Decode the 46- number to its LG equivalent (46-9980 → LT1000P and so on) using the cross-reference table above, or buy the LG number directly at typically better pricing.

Is ADQ36006101 the same as LT700P? Yes — ADQ36006101 is LG’s internal/part-number label for the LT700P retail cartridge. Same part, different packaging generation.

Where do I find filters for a discontinued LG model? Supersession first (the ADQ numbering often has a direct successor), then certified compatibles — the LT legacy compatible market is large and mature. Avoid cross-family “close fits”; they leak.

Related Guides

• How to Change an LG Refrigerator Water Filter — current LT1000P models, the 2025 notch change, ThinQ reset.
• How to Replace a Kenmore Refrigerator Water Filter — the 106/253/363/795 prefix decoder that ends wrong-cartridge orders.
• Kenmore Elite Filter Guide — the 795-vs-106 split inside the Elite line.
• How to Reset the LG Filter Light — panel and ThinQ methods.
• OEM vs Aftermarket Water Filters — the price-and-certification decision for legacy models.

Shop this guide: LG refrigerator water filters · LT700P – exact-fit chart