Every drop of wastewater that leaves a sink, shower, or toilet in a Colorado home or business enters the same basic infrastructure: a buried network of pipes and access structures called the gravity collection system. Understanding how that network is built — the pipes, the manholes, the cleanouts, and the hierarchy that ties them together — is the foundation every Class 1 collection system operator stands on before tackling anything more advanced.
How Wastewater Moves: The Gravity Principle
Unlike a water distribution main, which is pressurized and flows completely full, a gravity sewer is designed to move wastewater using nothing but the pull of gravity and a continuous downhill slope. Because the system relies on slope rather than pumps, a properly functioning gravity sewer is intended to flow only partially full, leaving an air space above the flow. That air space matters for