Knowing how to drain a toilet can save you a lot of mess when you are working on your toilet. There are several repair that cannot be performed without partially or completely draining the toilet. It is not hard, it just needs to be done before you work on the toilet.
Shutting Off the Water
Shut off the water supply to the toilet. There should be a water shut off valve on the wall or floor below the toilet tank.
Draining the Toilet Tank
Draining the toilet tank is a must to replace a toilet fill valve. Depending on the age of your toilet, there could be as much as five gallons of water in the tank. The toilet fill valve is attached via a hole in the bottom of the tank.
Even after the tank has been flushed and the water is off, there is still a lot of water in the bottom of the tank.
Turn off the water supply to the toilet first. Most tanks have a fill line marked on the side of the tank. Some do not. You can use a marker to put a mark at the correct water level if it is missing. Usually the fill line is to the top of the flush valve tube.
If it has been replaced it may be at a different level. Shut the water off. After that, flush the toilet to drain out most of the water from the tank. Place a pail below the nut for the toilet tank inlet. Loosen the nut on the water supply line. Let the remaining water drain out of the loosened nut.
There will be about an inch of water left in the bottom of the tank. You can use rags to try and get the rest of this water to drain into the tank. Or you can loosen the nut to the fill valve and let the water drain into the pail. Any water that you do not remove is likely to wind up on the floor. It is clean water, but is still wet.
Draining the Toilet Bowl
Flush the toilet. This will drain most of the water out of the tank. Additionally, most of the water will siphon out of the toilet bowl to.
At this point you will still have some water left in the tank and some water in the toilet bowl. To drain the tank completely, you will need to loosen the large nut on the bottom of the tank that holds the toilet fill valve in place. It is the larger nut closest to the tank. The lower nut is for the water supply line. Use adjustable pliers or a large adjustable wrench for this nut, it will be plastic or possibly brass. Place a small pail under the connection to catch the water that drains out of the tank. Loosen the nut until the water starts to drain out around the rubber seal. This should drain most of the rest of the water out of the tank. The remaining water can be soaked up with a rag. Re-tighten the nut after you are finished.
Use a plunger to force the remaining water in the toilet basin out. Get as much out with the plunger as you can. You can ladle the remainder out with a small paper cup or use a rag to soak it up. Remember to wear gloves for this part of the exercise.
Leave the water supply shut off. You should remove the water supply line from the tank. Loosen the nut that is just below the nut that holds the toilet fill valve in place. It is the nut that connects the water supply line to the tank. You can use adjustable pliers for this task, the nut is plastic on most newer toilets, chrome or brass on older ones. Remove the nut completely, so that the supply line is free from the tank.
Draining a toilet is needed for several toilet repairs. You may need instructions on other repairs after you have the toilet drained. For related information, see the articles 'Troubleshooting Toilet Problems', 'Fixing Clogged Toilets', 'Toilet Tank Problems', 'How To Fix a Leaking Toilet' and 'Toilet Bowl Issues'.