Plumbing is the system of pipes, tanks, and fixtures that brings clean water into a building and carries dirty water away. When you turn on a faucet, flush a toilet, or take a shower, you're using plumbing.

Modern plumbing is one of civilization's most important inventions, even if we rarely think about it. Before plumbing, people had to haul water from wells or rivers, and getting rid of waste was difficult and unsanitary. Cities with good plumbing systems are healthier because clean water helps prevent disease and proper drainage keeps communities clean.

A plumber is someone who installs and repairs plumbing systems. When a pipe bursts or a drain clogs, a plumber knows how to fix it. The work requires understanding water pressure, knowing which materials work best for different jobs, and sometimes crawling into tight spaces to reach pipes hidden inside walls or under floors.

The word also appears in everyday expressions. When something goes down the drain, people might say their plans have gone “down the drain.” And when everything in a system works smoothly together, you might hear someone say it's “good plumbing,” meaning the parts fit together well and work properly.