Q: What would cause water to drip from the back of my car’s muffler?
A: Auto manufacturers commonly put a “weep” hole on the rear, bottom part of the muffler. This allows water to exit, reducing inside corrosion. Water is a normal tailpipe emission created by the catalytic converter. The catalytic converter reduces harmful gases that come from the engine (e.g., carbon monoxide, hydrocarbons, and nitrogen oxides) and changes them into water, carbon dioxide, and nitrogen gas. The water that is dripping from your tailpipe is from this process and from condensation inside the exhaust system.