What is the best way to dispose of leftover or expired medicines

According to www.drugstore.com, the best and easiest way to dispose of leftover or expired medicines has been to flush them down the toilet. Which guarantees that children and pets can't eat them. However, trace amounts of medicines have been found in some water supplies so it is best to try to take expired medications to either a pharmacy or hazardous waste source for proper disposal.  An alternate suggestion would be to ask your pharmacist.