What you need to know before you start

A Delta shower cartridge controls water temperature and flow. When it fails, you get no hot water, no cold water, or water that won't shut off. Replacing it yourself takes about an hour and costs $30 to $150 for the cartridge alone, depending on the model. You do not need a plumber for this job.

The first step is identifying which Delta cartridge you have. Delta makes several types — the most common are RP, RP-Delta, and Monitor models. The cartridge number is stamped on the cartridge itself or printed in your original paperwork. If you cannot find it, you can remove the old one and take it to a hardware store to match it, or call Delta's customer service line with your faucet model number and they will tell you which cartridge fits.

You will need basic tools: an adjustable wrench, a screwdriver (usually Phillips), a cartridge puller (Delta sells these for $10 to $20, or you can rent one), and possibly a hex key. Most hardware stores stock Delta cartridges and pullers. If your local store does not have the exact model, order it online — it will arrive in two to three days.

Key Takeaways

  • Turn off the water supply to your shower before you begin, or you will have water spraying everywhere when you remove the cartridge.
  • The cartridge number is printed on the old cartridge itself — take a photo of it before you start so you buy the exact replacement.
  • A cartridge puller is essential; trying to force the cartridge out by hand or with pliers will damage the valve body and cost you hundreds more.
  • The entire job — removing the old cartridge, installing the new one, and testing — takes about an hour if you have all the parts on hand.

Turn off the water and remove the handle

Locate the water shutoff valve under your sink or in the basement. Turn it clockwise until it stops. If you cannot find a shutoff for just the bathroom, turn off the main water supply to the house. Turn on the shower to confirm the water is off.

Look at the handle. Most Delta handles have a small set screw or cap on the side or back. Use a screwdriver or hex key to remove it — it is usually a Phillips head or a 2mm hex. Once the screw is out, pull the handle straight toward you. It will slide off the stem. Set it aside.

If the handle is stuck, spray it with penetrating oil (like WD-40) and wait 15 minutes. Do not force it or you will crack the plastic. Some Delta handles have a decorative cap that pops off first — look for a thin line around the base and pry gently with a flathead screwdriver.

Remove the trim ring and cartridge collar

Behind the handle, you will see a trim ring — a decorative ring that sits flush against the wall. This ring screws on. Use an adjustable wrench to turn it counterclockwise. It may be tight; if it will not budge, spray it with penetrating oil and wait a few minutes.

Once the trim ring is off, you will see the cartridge collar — a cylindrical piece that holds the cartridge in place. This also unscrews. Use your wrench to turn it counterclockwise. Again, it may be tight. Once it is loose, you can usually unscrew it by hand.

If the collar is stuck and will not turn, do not force it. Spray it with penetrating oil, wait 20 minutes, and try again. Forcing a stuck collar can crack the valve body underneath, which is expensive to replace.

Pull out the old cartridge with a puller

The cartridge puller is a metal tool that threads onto the cartridge stem and pulls it straight out. Insert the puller onto the cartridge stem and thread it on by hand until it is snug. Do not over-tighten.

Once the puller is threaded on, turn the handle on the puller clockwise. It will pull the cartridge out slowly. This usually takes 30 seconds to two minutes. You may feel resistance — that is normal. Keep turning until the cartridge comes free.

If you do not have a puller, you can rent one from most hardware stores for $5 to $10. Do not try to remove the cartridge with pliers or a wrench — you will damage the cartridge stem and the valve body, and the repair will cost $300 to $500.

Install the new cartridge and reassemble

Before you insert the new cartridge, check the orientation. Most Delta cartridges have a flat side or a notch that must align with a corresponding flat or slot in the valve body. Look inside the valve body and find the alignment mark. Rotate the new cartridge so the flat side or notch lines up.

Insert the cartridge straight into the valve body. Push it in by hand until it is fully seated — you will feel it stop when it is all the way in. It should not require force. If it is hard to push, stop and check the alignment again.

Once the cartridge is in, screw the cartridge collar back on by hand, then tighten it with your wrench. Screw the trim ring back on. Turn the water back on at the shutoff valve. Test the shower — turn the handle to hot and cold to confirm both work.

Test for leaks and adjust the temperature limit

Turn on the shower and let it run for two minutes. Check under the sink for drips. If water is dripping from the valve body, turn off the water and tighten the cartridge collar another quarter turn. Turn the water back on and check again.

Most new Delta cartridges come with a temperature limit stop — a small plastic piece that prevents the handle from turning far enough to scald you. This stop is usually set to 120 degrees Fahrenheit. If your shower is too hot or too cold, you can adjust it by loosening the set screw on the stop and rotating it slightly. Make small adjustments — a quarter turn at a time — and test the water temperature between each one.

If water is leaking from the handle area, remove the handle and check that the set screw is tight. If it is tight and water is still leaking, the cartridge may not be fully seated. Turn off the water, remove the cartridge collar, and push the cartridge in again, making sure it is fully seated.

What to do if the cartridge will not come out

If the cartridge puller spins but the cartridge does not move, the cartridge is stuck. Spray the cartridge stem with penetrating oil and wait 30 minutes. Try again with the puller. If it still will not move, spray it again and wait overnight.

If the cartridge is still stuck after overnight soaking, the puller may not be gripping properly. Remove the puller and inspect the cartridge stem — it should be smooth and not stripped. If the stem looks damaged, you may need a plumber to remove it without damaging the valve body.

Do not try to force a stuck cartridge with a wrench or hammer. You will crack the valve body, and replacing it costs $300 to $500. Patience and penetrating oil are cheaper than a new valve.

Frequently Asked Questions

How do I know which Delta cartridge I need?

The cartridge number is printed on the old cartridge itself — look for a number like RP-19822 or RP-Delta. Take a photo of it and bring it to the hardware store, or order the exact model online. If you cannot find the number, call Delta customer service with your faucet model number and they will tell you which cartridge fits.

Can I replace a Delta cartridge without turning off the water?

No. When you remove the cartridge, water will spray out at full pressure. Always turn off the water supply first. If you cannot find a shutoff valve under the sink, turn off the main water supply to the house.

What if water leaks from the valve after I install the new cartridge?

Turn off the water and tighten the cartridge collar another quarter turn with your wrench. Turn the water back on and check again. If it still leaks, remove the cartridge collar and push the cartridge in to make sure it is fully seated, then reinstall the collar.

Do I need a cartridge puller, or can I remove it by hand?

You need a puller. Trying to remove the cartridge by hand, with pliers, or with a wrench will damage the cartridge stem and the valve body. A puller costs $10 to $20 to buy or $5 to $10 to rent, and it is worth every dollar.

How long does a Delta cartridge last?

Most Delta cartridges last 5 to 10 years, depending on water quality and how often the shower is used. Hard water and high mineral content shorten the lifespan. If your cartridge fails before five years, it may be defective — Delta offers a lifetime warranty on some models.