100 Gallon RV Fresh Water Tank 81" x 26" x 11" | Outlet & Vent Info

An upside-down installation and reuse of the red-plugged port as a vent are not confirmed for this tank. The color of a plug does not identify a port's function, thread, seal or approved orientation. Do not select an installation orientation from the product photo or assume a large opening is an unsealed inspection lid.

The current T100 listing identifies a nominal 100-gallon tank with 81 × 26 × 11-inch outside dimensions. LaVanture's August 2025 catalog, printed page 36, lists T100 with those same nominal dimensions, but does not specify the red plug, a particular lid or approval to invert the tank. Matching stock numbers and dimensions do not establish every supplied fitting detail.

The listing's gallery also contains a drawing marked T100W100 / 100 GAL TANK. It labels a separate “Ø1.00 VENT TUBE” and shows other openings and drill points. That diameter callout is not a one-inch pipe-thread specification, and the drawing does not identify the customer's red plastic piece or certify an inverted installation. Compare the actual tank's markings and port layout with the applicable supplied drawing before assigning fill, vent, outlet or access functions.

Have the tank's supplier or installer verify the intended support face, full-water load support, port elevations, vent routing and the seal and access requirements of any large cover. Keep the fill, vent and outlet functions distinct; a port moved by rotating the tank is not automatically suitable for a different function. No fitting size or adapter is established here: the earlier 1-inch/1½-inch fitting and 2¼-inch-hole grommet suggestions were not tied to the actual T100 ports. Do not drill or order those fittings from this answer. The approved orientation, red-plug function and suitability of a downward-facing cover remain unconfirmed.