How do I fix a running toilet?

Open the tank and check three common culprits. First, inspect the flapper: if it is cracked or warped, replace it. Second, check the fill valve: if water continues running after the tank is full, adjust or replace the fill valve. Third, ensure the chain connecting the flush lever to the flapper has about a quarter-inch of slack. These repairs cost under 20 dollars and take about 15 minutes.