What You Need to Do Before You Start

Replacing a pedestal sink is a project you can do yourself if you are comfortable working with basic plumbing connections and have the right tools. The job takes two to four hours and involves shutting off the water, disconnecting the supply lines and drain, unbolting the old sink, and installing the new one in reverse order. You will need a wrench, adjustable pliers, a bucket, and possibly a reciprocating saw or hacksaw if the old pedestal is bolted to the floor.

Before you buy a new sink, measure the rough-in distance — the distance from the wall to the center of the drain hole. Pedestal sinks come in standard sizes, but the drain location varies. Check that your new sink's drain will line up with your existing drain pipe, or you will need to move the pipe itself, which is a larger job. Also measure the width of the sink and the height of the pedestal to make sure it fits your space and does not block cabinet doors or windows.

Turn off the water supply to the sink. Look under the sink for shut-off valves on both the hot and cold lines. Turn them clockwise until they stop. If there are no shut-off valves, you will need to turn off the main water supply to the house. Open the faucet to release any remaining water pressure.

Key Takeaways

  • Measure the rough-in distance (wall to drain center) before buying a new sink, because drain locations vary and moving the pipe is a separate, larger job.
  • Turn off the water supply at the shut-off valves under the sink, or at the main if no valves exist, and open the faucet to release pressure.
  • Disconnect the supply lines and P-trap drain, then unbolt the sink from the wall and the pedestal from the floor before lifting the old sink out.
  • Set the new pedestal in place, bolt it to the floor, bolt the sink to the wall, and reconnect the supply lines and drain before turning the water back on.
  • Check all connections for leaks by running water and inspecting under the sink for drips before you consider the job complete.

Disconnect the Water Supply Lines and Drain

Place a bucket under the supply lines to catch any water that spills. Use an adjustable wrench to loosen the compression nut where the supply line connects to the shut-off valve. Turn it counterclockwise by hand once it is loose enough. Repeat for both the hot and cold lines. If the lines are corroded and will not budge, spray them with penetrating oil and wait 15 minutes before trying again.

Next, disconnect the P-trap — the curved pipe under the sink that holds water to block sewer gases. Loosen the slip nuts on both ends of the P-trap using an adjustable wrench or pliers. The nut closest to the wall connects to the drain line; the nut closest to you connects to the sink drain. Once both nuts are loose, pull the P-trap straight down and out. Water will drain from it, so keep the bucket underneath.

If the P-trap is stuck or corroded, do not force it. Spray the slip nuts with penetrating oil, wait 15 minutes, and try again. If it still will not move, you may need to cut it out with a reciprocating saw or hacksaw. You will replace it with a new P-trap anyway, so do not worry about damaging it.

Remove the Old Sink and Pedestal

Look at the underside of the sink where it meets the wall. Most pedestal sinks are bolted to the wall with two or four bolts that run through a mounting bracket. Use an adjustable wrench or socket wrench to remove these bolts. Keep them in a safe place — you may be able to reuse them, or you may need new ones if they are corroded or the wrong size for your new sink.

Check the base of the pedestal where it meets the floor. Some pedestals are bolted down; others are just caulked in place. If there are bolts, remove them with a wrench. If the pedestal is only caulked, use a utility knife or caulk removal tool to cut the caulk around the base.

Once the sink is unbolted from the wall and the pedestal is unbolted from the floor, lift the sink straight up and off the pedestal. It will be heavy — ask someone to help you. Set it aside. Then lift the pedestal straight up and out of the way. If the pedestal is stuck to the floor with caulk, rock it gently side to side to break the seal, then lift.

Install the New Pedestal and Sink

Before you set the new pedestal in place, check that the floor is clean and level. If the floor slopes, the pedestal may rock. Use a level to check. If it is not level, you may need to shim the pedestal with metal shims under one or more feet, or you may need to use a self-leveling caulk under the base.

Position the new pedestal so that the drain hole in the sink will line up with your existing drain pipe. Set the pedestal in place and check that it does not rock. If it does, adjust the shims or caulk. Once it is stable, bolt the pedestal to the floor if your new pedestal has bolt holes. Use the bolts that came with the pedestal, or use stainless steel bolts rated for bathroom use.

Carefully lower the sink onto the pedestal. The sink should sit flat and stable. If it rocks or tilts, the pedestal is not level — stop and fix it before you go further. Once the sink is seated, bolt it to the wall using the mounting bracket and bolts. Tighten the bolts evenly so the sink does not tilt. Do not over-tighten; you only need them snug enough that the sink does not move.

Reconnect the Water Supply and Drain

Slide the new P-trap into place under the sink. The end with the larger diameter goes up into the sink drain; the end with the smaller diameter goes into the wall drain. Hand-tighten the slip nuts on both ends, then use an adjustable wrench to tighten them another quarter turn. They should be snug but not so tight that you cannot loosen them by hand if you need to later.

Connect the hot and cold supply lines to the shut-off valves. If your old supply lines are in good condition and the right length, you can reuse them. If they are kinked, corroded, or the wrong length, replace them with new braided stainless steel lines. Hand-tighten the compression nut, then use a wrench to tighten it another quarter turn. Again, snug but not over-tight.

Before you turn the water back on, place a bucket under the P-trap and supply lines. Turn on the shut-off valves slowly by turning the handle counterclockwise. Open the faucet and let water run for 30 seconds to flush out any debris in the lines. Then close the faucet and check all the connections — the supply line nuts, the P-trap slip nuts, and the drain connection at the wall — for drips or leaks. If you see water dripping, tighten that connection a quarter turn and check again.

Seal and Finish

Once all connections are dry and tight, explore caulk around the base of the pedestal where it meets the floor. Use a silicone or acrylic caulk rated for bathrooms. Run a bead of caulk around the entire base, then smooth it with a wet finger or caulk tool. This prevents water from seeping under the pedestal and keeps the base clean.

explore caulk around the mounting bracket where the sink meets the wall. This seals the gap and prevents water from running down the wall behind the sink. Let the caulk cure for 24 hours before you use the sink heavily.

Run the water one more time and check for leaks. If you see any drips, tighten the connection that is leaking a quarter turn. If the leak does not stop, turn off the water, disconnect that line, and check the compression nut or slip nut for damage. You may need to replace the nut or the ferrule (the small ring inside the nut that seals the connection).

Common Mistakes to Avoid

The most common mistake is not measuring the rough-in distance before buying the new sink. If the drain hole does not line up with your existing drain pipe, you will have to move the pipe, which requires cutting into the wall or floor and rerouting the drain line. This turns a two-hour job into a full day or more. Measure twice and confirm the drain location before you buy.

Another mistake is over-tightening the bolts that hold the sink to the wall or the pedestal to the floor. If you tighten too much, you can crack the sink or strip the bolt holes. Tighten until snug, then stop. The same rule applies to the supply line and P-trap nuts — hand-tight plus a quarter turn is enough.

Do not forget to turn off the water before you start. If you skip this step and a supply line comes loose, water will spray everywhere and you will have a mess. Always shut off the water first, even if you think you can work fast.

Frequently Asked Questions

Can I reuse my old supply lines and P-trap?

You can reuse the P-trap if it is in good condition — no cracks, corrosion, or kinks. You can reuse supply lines if they are braided stainless steel and the right length. If they are old rubber or plastic, or if they are kinked or corroded, replace them. New supply lines and P-traps are inexpensive and prevent leaks later.

What if the new sink drain does not line up with the old drain pipe?

You will need to move the drain pipe. This involves cutting into the wall or floor, removing the old pipe, and running a new one to the correct location. This is a larger job that may require a plumber. Before you buy a new sink, always confirm that the rough-in distance matches your existing drain.

Do I need to use plumber's putty or caulk under the sink?

Use caulk, not putty, around the base of the pedestal and where the sink meets the wall. Putty is for sealing the drain opening inside the sink. Caulk prevents water from seeping behind the pedestal and keeps the base clean. Use silicone or acrylic caulk rated for bathrooms.

How tight should I make the bolts?

Tighten all bolts — the ones holding the sink to the wall, the pedestal to the floor, and the supply line and P-trap nuts — until snug, then stop. A quarter turn past hand-tight is usually enough. Over-tightening can crack the sink, strip the bolt holes, or damage the compression nuts and ferrules.

What should I do if a connection leaks after I turn the water back on?

Turn off the water, place a bucket under the leak, and tighten that connection a quarter turn. Turn the water back on and check. If it still leaks, turn off the water again and disconnect the line. Check the nut and ferrule for damage or debris. Clean the ferrule and reconnect, or replace the ferrule if it is cracked or worn.