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In short
A new cartridge that still drips usually means one of five things. Check them in this order.
Shut off the water before you take the trim apart again. On pressure-balancing valves, always use a matching pressure-balance part. Never swap in a plain cartridge or remove the balancing spool to "fix" low flow, because that removes the scald protection.
1. The seats and springs are worn (Delta and similar)
Some valves seal against separate rubber seats pushed by small springs behind the cartridge. A new cartridge won't fix worn seats.
- Delta Monitor 1300/1400: Delta's parts diagram lists RP4993 seats & springs next to the RP19804 cartridge, and a Delta staff answer names RP4993 as the rebuild kit. Delta RP4993 on deltafaucet.com
- Glacier Bay / Pegasus (Danco 89932 style): Danco support names its model 80684 for the seats and springs behind that cartridge.
2. Debris or scale in the valve body
Moen recommends cleaning and flushing the valve body every time you install a cartridge, because mineral build-up and loose debris can damage a new cartridge or block flow. Kohler says the same for Rite-Temp valves and adds burrs: clean with 50/50 white vinegar and water, and remove brass burrs with a Scotch-Brite pad without scratching the sealing surfaces.
3. The cartridge isn't fully seated, or an O-ring moved
- Moen 1222: the H&C tab must be up and flush with the valve body, and you shouldn't rotate the cartridge while inserting it. The oval grommets aren't fixed in place and can fall off. If the retainer clip won't slide in, the cartridge isn't flush.
- Kohler Rite-Temp: press the PBU in straight. Kohler says tilting and rotating it moves the small O-rings and causes leaks.
- Water left in the bottom of the valve body can stop a cartridge seating fully. Moen says to blot it out with a rolled paper towel.
4. It's the wrong cartridge
A cartridge that "almost" fits can still leak. Compare the part number against your valve model, not just the brand. Moen 1222 vs 1225 and Delta RP46074 vs RP19804 are the classic mix-ups. See Moen 1222 vs 1225 and the Delta identifier.
5. Pressure-balance spool stuck (Delta)
Delta lists these symptoms for its RP46074: drips when off, a leak inside the handle, low flow on one temperature, or only one temperature. Its check: remove the cartridge with the handle in the full-on position and shake it. A rattle means the spool is free. No rattle: tap it, soak it in 1:1 water and white vinegar for 30 minutes, or replace it.
Where is it dripping?
- From the spout or showerhead with the handle off: seats, cartridge seals, or debris (sections 1 to 3).
- From behind the handle or escutcheon: cartridge O-rings or bonnet/cap seals. If water shows up inside the wall, shut it off and call a plumber.
- Showerhead drips for a minute after shutting off: often just water draining from the pipe above the valve. Wait and see whether it stops.
Sources
Fetched and checked 2026-10-21. Part numbers change; confirm against your own valve and the maker before buying.
- Delta parts diagram: Monitor 1300 & 1400 (RP4993 seats & springs)
- Delta product page: RP19804 (staff answer naming RP4993)
- Delta product page: RP4993 Seats & Springs
- Delta support: RP46074 (symptoms, rattle test); read through a search-index copy because the direct fetch failed
- Moen Solutions: Valve Body Cleaning and Flushing
- Moen Solutions: 1222 Cartridge (seating and clip)
- Kohler Assist: Rite-Temp K-304 service parts (O-rings, burrs)
- The Home Depot: Danco 89932 (Danco answer on seats and springs, 80684)
