Basement Toilet Installation

Corner of a bathroom with a toilet
  • 1-2 hours
  • Intermediate
  • 150-400
What You'll Need
Toilet bowl gasket, made of wax, with a rubber flange
New toilet
Toilet supply hose, flexible
What You'll Need
Toilet bowl gasket, made of wax, with a rubber flange
New toilet
Toilet supply hose, flexible

You can install a basement toilet quite easily if the pipes for water and sewage are already roughed in.

Adding an extra basement toilet in a house can make life easier not only for family members, but also for when you have guests.

It’s not as big a job as it seems and it’s one most people can undertake, even without plumbing experience.

Step 1 - Install Water Line

Make sure the water line is switched off. Start on the basement toilet by installing the flexible toilet supply hose from the water line.

The supply line needs to be between nine inches and 12 inches off the floor. Fit it with a shutoff valve where a turn of 90 degrees shuts off the water to the toilet.

The lines should run to the left side of the toilet.

Step 2 - Replace or Install Toilet Gasket

removing caulking from space where toilet was removed

There will be a cover on the floor and this can accommodate a basement toilet. Before you can fit the gasket, however, you need to remove the cover.

Do this by tapping it with a hammer. This will loosen it and it will break away. Now, you’re ready to fit in the wax gasket.

Seat it in the hole, making sure it’s secure, and with the rubber flange in the drain. The wax seal has to be on the floor flange. This will make sure everything goes down into the drain from the basement toilet with no leakage.

Step 3 - Seat the Toilet

You’ll see holes in the flange that sits on the floor. Install the bolts that came with the wax seal into these—they’re known as closet bolts.

Then adjust them around until you’re able to draw a line between them that’s centered directly over the middle of the drain and is parallel to the wall.

Now, you’re ready to set the toilet on the bolts. The base of the toilet will have four holes. As you start to set the toilet down, align it with the bolts and lower it gently.

It helps if you have someone to help you with this step. When you’ve lowered the toilet, the closet bolts should protrude from the base.

Step 4 - Fit the Toilet

Man installing a toilet lid

You need to make sure the toilet is firm on the seal. Attach the toilet seat and sit on the toilet. This will give enough weight to press the toilet down into the wax seal for a firm join.

To fit the toilet in place, place a washer on each bolt and use the nuts that come with the toilet. Tighten these until they’re hand tight.

Follow this by tightening with a wrench. You don’t have to over-tighten since this can crack the porcelain—just make sure the toilet doesn’t rock.

If any of the bolts are exposed, you can remove the extra with a hacksaw.

Step 5 - Finish Up

To complete your basement toilet installation, set the tank on the toilet and secure it in place.

Attach the water supply line to the toilet and open the valves so it can fill.

Check the level of water in the tank.

Flush the toilet and check it refills properly.