Venting

Fresh tank

Air must leave during filling and enter during pumping. A blocked or undersized vent can swell or collapse the tank. Route the vent high, avoid siphon geometry and terminate against insects, dust and splash without sealing airflow.

Waste tanks

Grey and black vents let displaced air escape and send odor outside. Terminate away from windows/intakes and follow applicable plumbing/RV rules. Do not connect fresh and waste vents.

Loops and siphons

A high loop can reduce spill during turns, but low spots can trap water and block breathing. Test filling, draining, hard braking and off-level parking.

Diagnosis

Tank deformation, slow fill, burping drains and odor are vent clues. Inspect the entire path; a clean exterior screen does not prove the hose is open.

Build rule

If you cannot reach it, isolate it, drain it and explain its pressure/temperature or water-quality job, it is not ready to hide behind a wall.

CHAPTER CHECK

• I can explain the purpose and failure mode of each item in this chapter. • I know which manufacturer limit or water-quality claim controls my choice. • I added the valve, access, drain, measurement or maintenance task to my drawing/checklist.