If you have ever been in a situation where you push the lever on the back of the toilet expecting it to flush and instead you only hear a clink, you know what it is like to have a chain break in the toilet. You have to open the tank cover, fish down in the cold water with your hand until you find the rubber stopper and lift it manually to allow the flow of water to flush the toilet. You can replace the chain in the back of the toilet with just a few simple steps.
Turn off the water at the back of the toilet near the floor. There should be a pipe coming out of the floor or wall with a valve on it. Turn this valve clockwise so that the water is off.
Open the water tank on the toilet. This is usually a ceramic thick lid that can be lifted straight up. Be careful to place it in a safe position so that it does not fall and crack, such as flat on the floor.
Locate the broken chain. One end of it should be on the flapper that keeps that water from leaving the tank until the handle has been pulled. The other end should be on the handle that is attached to the wall of the tank.
Open the links that are still attached by stretching them open with the needle nosed pliers and removing them. Set the chain on a surface and measure it to get the right length for the new chain. If the chain is too long it won't pull the flapper and if it is too short it won't let the flapper sit correctly.
Open a link on the end of the new chain by stretching it with the needle nosed pliers and attach it to the flapper. Close it by squeezing it with the pliers. Open the link on the other end and attach it to the inside of the handle. Squeeze the link shut.
Try pushing the handle to see if it lifts the flapper correctly and if it then allows it to sit flat on the bottom of the tank. If it does, turn the water back on at the valve behind the toilet. Watch the tank fill up and then try flushing it with the lid still open to see if the new chain works. Close the lid when you are assured of a working chain and use the toilet as before.