Question: Why is my outdoor faucet backing up into my basement? Help, please! It’s fine when I run the outdoor faucet without the hose, but when I attach the garden hose, I can’t stop the water from flowing into my basement.
Answer: It is possible that your hose bib froze in the winter, causing the faucet pipe to crack. You should have a frost-proof sill cock; the valve can be shut off from the inside of the home. The crack is small enough to avoid leaking while there is no back pressure, but once you raise the back pressure it leaks in the home.
What You Can Do
If your outdoor faucet is backing up into the basement, you need to replace your sill cock. Every winter, detach your hose before the temperature freezes to keep your faucet from freezing, and insulate your hose bib.
Learn how to winterize your outdoor plumbing.