Replacing an old toilet is a job most home owners can do as a DIY project, assuming the new toilet is going in the same place as the old one. If not, you will have to run a new water supply line and drain pipe which must be connected to the drain and venting system.  That is probably more work than the average home owner wants to do, so if you are relocating the toilet, you might want to pay someone to do the job.

However, simply replacing an existing one in the same place is a task that can be accomplished in a couple of hours, depending on your skill level. Just about everything you need to install a toilet will come with it, but there are several things you will have to buy separately like the toilet seat and a wax ring, which is the item that sits at the base and forms a water tight seal.

When you purchase a new toilet, be sure to get the right size wax ring and toilet seat based on the manufacturer’s recommendation. You may need to pull out the owner’s manual in the store to get that information. Most are standard sizes, so the people working in the home improvement store should be able to help you with that.

Before You Begin

Before you start to tear up your bathroom, go and buy everything you need.

  • Toilet and toilet seat
  • Wax ring
  • Plastic toilet shims
  • Plumber’s putty
  • Black marker
  • Pipe compound
  • Rubber Gloves
  • Screwdriver
  • Hacksaw
  • Tube cutter
  • Two adjustable wrenches
  • Ratchet wrench and socket set
  • 3 ½ inch closet bolts or concrete screws if applicable

One thing to note before you buy your new toilet. You have to measure your toilet drain to the wall which will determine the size of your toilet. Most toilets are made for a drain opening  11 – 12 inches from the wall. If you have trouble finding the right toilet, there are also flange adapters you can buy that will give you a couple of more inches to play with further away or closer to the wall.

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Removing the Old Toilet

Your primary goal in this task is to not get toilet water all over you or the floor and to cover the drain quickly so sewer gas does not come up into your home. Be sure you are wearing your rubber gloves to avoid bacteria.

  1. Turn off the water supply line at the shutoff valve. Flush the toilet several times until the tank empty.
  2. Soak up the excess water in the tank with a rag
  3. Disconnect the water supply tube.
  4. Unscrew the tank bolts that connect it to the toilet bowl using a ratchet.
  5. Once the bolts are removed, careful lift the tank  and place to the side
  6. Remove the toilet base by unscrewing the floor bolts. One the bolts are off, you may need to rock the toilet back and forth to break the wax seal.
  7. Lift it off the bolts and set it down on an old towel.
  8. Immediately plug the drain in the floor with an old towel.
  9. Scrape all of the old grime off the flange in the floor. If it appears in good shape, you can reuse it. If not, replace it or use an adapter over it.
  10. Place the toilet and tank in a large trash bags and carry them outside for disposal.

Note: Sometimes the nuts and bolts on toilet bowls are so corroded, it is impossible to get them to turn. If that is the case, first try some penetrating oil before trying again. If that does not work, you can use a hacksaw to cut into the nut at an angle to develop a groove, then try prying it off with a screw driver.

Installing the New Toilet

Install a New Toilet
Credit: Opensource

Now that the old toilet is out of the way, the new one should go in much faster.

  1. First, set the mounting bolts in the old flange using the 3 ½ inch flange closet bolts you bought. Again, you can use a new flange if it is damaged. If you have a concrete floor, use self-tapping concrete screws.
  2. Tighten the bolts in place with a nut to keep them straight.
  3. Turn the new toilet over and place a no-seep wax ring on the bottom around the drain hole. Press down on all sides of the ring to insure a good seal.
  4. Flip the toilet back over carefully, then sit it on the flange lining it up with the flange bolts through the holes in the toilet base. Toilets are heavy and awkward so you may need additional help during this step.
  5. Once the toilet is sitting on the floor with the anchor bolts through the base holes, sit down on the toilet and rock it back and forth to seal the wax ring below.
  6. Place a washer over each closet bolt and tighten a nut by hand down to the bottom to prevent scratching the porcelain on the toilet.
  7. Once at the bottom of the bolt, use a wrench to tighten the nut ½ turn, then alternate to the other side turning a ½ turn each time so one side does not get ahead of the other. Take your time. If you try to tighten too fast, it will crack the base.
  8. If the toilet rocks or is not level, use plastic shims then break them off so they cannot be seen from the outside.
  9. Using the hacksaw, cut the flange bolts so that only ¼ inch of it is exposed.
  10. Now cover the flange bolts with the caps that came with the toilet. Some snap on, while others require that you put plumber’s putty inside the cap to seal it over the bolt.

Installing the Tank

Place the anchor bolts in the holes of the tank before you attempt to lift it upon the toilet. The Replace Your Old Toilet with a New OneCredit: Opensourcebolts will help you guide the tank in place.

  1. Lift the tank and place it over the bowl. Again, you may need help at this point because the tank can be heavy even though it does not have water in it.
  2. Guide the tank bolts into the hole on the toilet bowl.
  3. Tighten the tank bolts by holding the bolt stationary on the bottom of the tank with a wrench, while tightening the bolt on the inside of the tank with a screwdriver. Do not over tighten or you can crack the porcelain.
  4. Install the shut off valve by setting it over the compression ring and screw the nut to it by hand until it will not tighten anymore.
  5. Use one adjustable wrench to hold back the valve and another wrench to tighten the compression nut.
  6. Use a new water supply line and screw it into place.
  7. Connect the supply line to the bottom of the tank. Slide the compression nut over the end of the shutoff valve.
  8. Tighten the compression nut with an adjustable wrench
  9. Turn on the water supply and check for any visible leaks.
  10. Flush the toilet several times and look around the base for water.

Note: Do not seal the base of the toilet with silicone caulk. This is a common mistake by home owners and some professionals. If there is a leak in the future, the caulk will prevent you from seeing it and will eventually damage the subfloor. 

Final Thoughts

Installing a new toilet is not difficult but you will be dealing with awkward and heavy items, and it can get dirty if you are not careful. Removing the toilet will probably take longer than installing the new one.

After you are finished, be sure to check for leaks immediately and watch the area over the next few days. If you followed all of the procedures correctly, you should not have an issue.

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