Install a Toilet in 12 Steps

Updated: Aug 27, 2021

Installing a toilet is a fairly straightforward DIY project that requires no specialized tools, and the new toilet usually includes everything you need to do the job. To install the new unit, you’ll need a new gasket and two 5 /16-inch bolts to mount the bowl to the floor flange. The following instructions apply to installation of standard two-piece toilet, in which the tank and bowl are separate components. (See side note below on installing a new single-piece toilet.)

STEP 1 If removing an old toilet, first shut off the water supply and flush the toilet. Use a bucket or cloth to remove any leftover water in the tank and bowl. Using a pair of pliers or small pipe wrench, remove the nut connecting the water line to the valve at the bottom left side of the tank. Remove the two nuts attaching the bowl to the floor flange with a crescent wrench. Once they’re removed, lift off the old toilet. Scrape away old gasket material to expose the plastic drain flange (the mounting base for your new toilet). Discard the old bolts.

STEP 2 Place the two new 5 /16” bolts (included with toilet) in the holes located on the sides of the exposed flange, with the bolt heads inside the flange. Position the two bolts straight up and across from each other. Then put the new toilet gasket (wax ring) on the flange, with the flat side pointing up (if tapered).

STEP 3 Lower the bowl straight down, centered on the wax ring; Ensure the bolts come though the holes on each side of the bowl. Apply pressure straight down; pushing the bowl over the ring and flange squeezes the wax to create a seal.

STEP 4 Add washers and nuts to the protruding bolts and tighten them; be careful not to crack the bowl.

STEP 5 Push a pair of 5 /16 -by-3” mounting bolts through the small holes on the tank’s bottom. Place rubber washers just beneath the bolt heads for a watertight seal. Add nuts and washers to the bolts on the underside of the tank and tighten until snug.

STEP 6 Apply the sponge-rubber gasket (small side down if beveled) over the discharge tube where the tank sets on the bowl.

STEP 7 Set the tank on the bowl, threading the bolts into the bolt holes on the bowl and sandwiching the gasket between the tank and bowl.

STEP 8 Add metal washers and nuts to the bolts on the tank’s bottom. Hold the tank level and tighten. Keep each bolt stationary with a screwdriver while backing up the nut with a crescent wrench. (Avoid over-tightening, which can crack the porcelain.)

STEP 9 Screw the flush handle to the lift arm through the hole in the tank (threaded in reverse). Connect the lift arm to the chain of the flushing ball/flapper inside the tank.

STEP 10 Bolt the new toilet lid to the bowl.

STEP 11 Install a new water line from the wall or floor valve to the feed valve on tank’s underside. Turn on the water, check for leaks, and try a few trial flushes. If your toilet holds water, tighten the bolts that hold the bowl to the floor. Adjust minor spacing issues or instability between the tank and bowl (or bowl and floor) with hard rubber shims.

STEP 12 Once everything is in place, use a hacksaw, buzz cutter, or similar tool to cut the ends off the mounting bolts to accommodate the plastic caps. Replace the tank cover and your new toilet is ready.

Editor's Note: This article originally appeared in The Quick and Easy Home DIY Manual by HIR's editor Matt Weber, now available at Amazon and other fine book retailers.

Side Note

Installing a Single-piece Toilet

One-piece toilets (such as the Kohler Santa Rosa model shown above) are popular because they integrate the tank and bowl into a single seamless design which adds a contemporary look to your bathroom. The seamless design also eliminates the joints and nooks that accumulate grime, so these toilets are very easy to clean. Furthermore, installation is further simplified by eliminating the need for tank-to-bowl bolts or a tank gasket. By combining the tank and bowl, however, these one-piece toilets are heavy—often more than 100 lbs.—so you should recruit and assistant to help lift the unit into place over the wax ring.