Blue boy

A blue boy is a wheeled portable waste tank (15–40 gal / 55–150 L) used to haul black or grey water from an RV to a dump station without moving the RV itself. The nickname comes from the distinctive blue plastic of the original Barker Manufacturing models.

Built as a sealed plastic tank with wheels, a tow handle, and a small ball coupler so it can be slow-towed behind a car or bike. Filled through the RV dump valve with a standard sewer hose; emptied at a dump station. Popular brands: Barker Tote-Along, Camco Rhino, Thetford SmartTote. A common alternative to a honey wagon for long stays in the US.