Some of the uses that people have found for Coca Cola are almost legendary. Rumor has it that highway patrol officers keep it in the trunk to clean the road after an accident. Whether that is true or not, many people use Coke to clean the battery terminals in their cars. If Coke can clean stains from pavement and corrosion from batteries, there's no reason why it can't clear clogs from your drain.
The complete list of ingredients in Coke is a closely-guarded secret, but the label lists carbonated water, caramel, cane sugar, flavor, caffeine and phosphoric acid 338. The latter is added to give the drink a tangy flavor. It is a mildly corrosive acid used primarily in the manufacture of fertilizer and detergents. Among its industrial uses are cleaning rust off metal in preparation for painting. The material safety data sheet lists phosphoric acid as dangerous, highly corrosive and harmful. Ingestion can lead to severe burns of the mouth, throat and stomach. The concentrations in Coke, however, are too small to be harmful.
Coke as a Drain Cleaner
Most over-the-counter drain cleaners, unless they are enzyme-based, contain sodium hydroxide, also known as caustic soda. It woks by increasing the alkalinity of the water in the drain until it is high enough to dissolve clogs. Stronger ones for professional use, on the other hand, usually contain sulfuric acid, which raises the pH in the opposite direction. The phosphoric acid in Coke works in the same way as sulfuric acid but not as quickly. It is a weaker acid and present in a much smaller concentration in Coke than sulfuric acid in drain cleaner. Consequently, you have to leave it in the drain longer.
How to Clean Your Drain With Coke
Coke is really only effective if your drain is completely clogged because it needs a long time to work. If you pour it into a partially clogged drain, it will just pass through without any noticeable effect. The drain should also ideally be free of standing water that will dilute the Coke. If your clog meets these conditions, pour an entire 2-qt. bottle down the drain and let it work overnight. Check the drain in the morning, and if the clog has cleared and there is no more Coke, flush it with hot water.
You have more effective ways to clear your drain than pouring a bottle of Coke into it. If you don't want to use a commercial drain cleaner out of concern for your pipes and its potential adverse effects on the environment, make a mixture of peroxide and baking soda and pour it down the drain. Baking soda is mildly alkaline and will deodorize as it cleans while the foaming action of peroxide will loosen debris. Add vinegar to the mixture to get the benefit of a mild acid. You can adjust the relative concentration of each ingredient to get the best results.