Write an article based on this "Turn off the water supply to the toilet. Mark the water level in the tank with a marker or a pencil. Add coloring or food dye to the water and wait 10 minutes. Check the water in the toilet bowl to see if it’s changed color. Look to see if the water level in the tank has gone up or down. Check if the dyed water from the tank has leaked onto the floor."
Locate the shutoff valve in back of the toilet, connected to a pipe coming out of the wall. Turn this valve clockwise as far as you can to turn the water off. Make the mark at the highest point where the water in the back of the tank reaches. This will help you to determine whether the water in the tank rises or falls over time. For best results, use a sharpie; a pencil mark will work, but it may be washed away if the water rises. Add 1 dye tablet or 10 drops of food coloring to the water in the tank. Dyeing the water this way will allow you to see whether the water in the tank is leaking into the toilet bowl.  You can normally purchase water dye tablets from your local water provider. Be sure to wait at least 10 minutes so that the water in the tank will completely change color. If the water in the bowl has any trace of the dye you put in the tank, the water in the tank has leaked into the bowl. This means the cause of your leak is a faulty flush valve. If you have a damaged flush valve, it will have to be replaced. If the water has risen, this means there’s probably something wrong with the fill valve. If the water has gone down, there’s a probably a leak in your flush valve. If the water level has gone up, check to see if there’s any water in the overflow tube. This would also indicate that the fill valve is leaking and overflowing the water in the tank. If dyed water has seeped out from the bottom of the tank and onto the floor, this means it’s probably a leaky gasket. If dyed water has come out of the body of the tank, the tank itself may be cracked. Unfortunately, if the tank is cracked, it will have to be completely replaced.