How to replace a Delta faucet cartridge

Start with the faucet type, then the part. Delta's parts page for kitchen leaks lists the single-handle options and how it describes each:

DST stands for DIAMOND Seal Technology. Delta's instruction insert says the RP50587 fits all DIAMOND Seal Technology kitchen and lavatory models that use the 36 mm Delta motion cartridge. If your faucet has a ball inside instead of a cartridge, you have a different repair and different parts.

When you can't tell, Delta's Product Identifier Tool walks you through questions and ends on a product page with a parts list and a diagram. You'll need the model number, which is often stamped under the spout or on the supply lines. Our page on how to fix a dripping faucet covers telling cartridge, ball and compression faucets apart.

Delta's RP50587 insert gives a short list. Here it is with the practical details added.

1. 1Shut off the water. Close the supply valves under the sink. If you're not sure how, see how to shut off water to a fixture. Cover the drain and open the faucet to release pressure.
2. 2Remove the handle, trim cap and bonnet nut. Delta notes that on some DST models the trim cap screws off, and on others it's pried off. Go gently either way. The bonnet nut is what holds the cartridge in the body.
3. 3Lift out the old cartridge.
4. 4Check the seal on the new cartridge. Delta says to insure the seal is in place on the bottom before you install it.
5. 5Set the new cartridge. Line up the guide pins on its bottom with the pin openings in the faucet body.
6. 6Tighten the bonnet nut with a wrench. Delta warns that failing to tighten it securely with a wrench could result in water damage. Hand tight isn't enough.
7. 7Reinstall the trim cap and handle. Then turn the water back on slowly.

The Home Depot's cartridge guide adds two tips that apply to any brand. Take the old O-ring, spring and cartridge to the store, and note the faucet's manufacturer and model number, so the new part matches. And if hot water comes out of the cold side afterward, rotate the cartridge half a turn and the taps will work as normal. Delta also says not to try to take the cartridge apart, because there are no repairable parts inside. That's the whole job. If a leak persists after the swap, or the faucet leaks from the spout, Delta's advice is to shut off the water and replace the valve cartridge again, making sure the bonnet nut is tight.

### Can you limit how hot the handle goes?

Yes. Delta says this faucet has an integrated handle limit stop with two positions. Position 1, to the left, allows full handle motion between all cold and all hot, and it's how the faucet leaves the factory. Position 2, to the right, allows half the normal motion, from all cold to a mixed hot and cold. To change it, remove the handle, move the valve stem to the all-cold position so the water is on, change the position, turn the water off and reinstall the handle. Delta cautions that the stop may help prevent scalding but won't always prevent it, because it doesn't compensate for incoming pressure or sudden temperature changes.

Tub and shower valves use different cartridges. Delta's instruction sheet for the 1300/1400 and 13/14 series covers two of them, and the first step is knowing which is installed, since Delta says the cartridges are not interchangeable.

• If the cap is white, it's a 1300/1400 series cartridge, part RP19804.
• If the cap is grey, it's a 13/14 MultiChoice cartridge, part RP46074.

The steps, in Delta's order:

1. 1Shut off the water supplies. Delta capitalizes the warning, and so should you.
2. 2Remove the handle, then pull off the sleeve. If needed, slide the O-ring toward you, but don't pull it over the bonnet.
3. 3Unscrew the brass bonnet counterclockwise.
4. 4Remove the cartridge. For a 13/14 MultiChoice, put a flat head screwdriver in the notch of the cap and turn to raise it out. For a 1300/1400, don't pry it with a screwdriver. Reinstall the handle on the brass stem and rotate counterclockwise while lifting the cartridge out of the two notches on the sides of the body.
5. 5Don't twist the new cartridge's cap and lower housing apart. If they separate, twist them back until they snap together, and never take the lower housing apart.
6. 6Install the cartridge with the words "Hot Side" over the hot water inlet, pressing it in until the keys fully engage the slots in the body. Delta says that applies to back-to-back or reversed installs too.
7. 7Reassemble the bonnet, slide the sleeve over the O-ring and reinstall the handle. On a 1300/1400 only, remove and throw away the black retention plug from the brass stem.

### Why flush before you use it?

Delta's last step is to flush the system. Turn the supplies on, check for leaks and let the lines run for one minute without moving the handle. If the valve feeds a showerhead, take the head off and divert the water for 30 seconds. Delta says this clears debris from the supply lines that can damage internal parts and cause leaks. Then test the valve to make sure cold water flows first.

### Set the rotational limit stop

The same sheet has a limit stop adjustment that matters for safety. Delta says most industry standards cap the maximum water temperature exiting the valve at 120 degrees Fahrenheit, and your local code may require less. Delta's method is to run the water, put the handle on, turn it counterclockwise until it stops, and hold a thermometer in a plastic tumbler in the stream. If it reads above 120, move the stop clockwise to cool it. Delta says each tooth can change the temperature by 4 to 16 degrees, and the setting may need a seasonal readjustment because cold water gets colder in winter. It also warns that leaving the disc off after setting the stop could cause scald injury.

Those use stem units, not one cartridge. Delta's instruction sheet for the RP47422 and RP54801 repair kits is short: remove the handle, unscrew the bonnet nut, pull out the stem unit, and reassemble in reverse order, with the tabs on the cartridge aligned with the slots in the body and the bonnet wrenched tight. Orientation matters here, because the stops have to point the right way for the handle to turn properly. If the faucet has very low flow, Delta says to clean the seats and springs of debris first.

If the valve is behind a wall, the bonnet won't budge or a fresh cartridge still leaks, it's worth a professional look. Phoenix water is hard, and scale can seize a bonnet nut or clog a seat. Our page on how hard water damages plumbing explains why. For a shower, how to replace a shower cartridge covers the general process. HQ Plumbing & Air is licensed and insured, gives free estimates and quotes an upfront price before work begins, and offers 24/7 service if a leak can't wait.