Bathtubs with outlet below the drain
A bathtub with a direct drain allows the p-trap to be attached directly below the tub outlet. Water drains directly from the tub drain to the p-trap:
A standard tub drain has the outlet below the overflow pipe. Water drains from the tub to the overflow pipe, then into p-trap.
For Freestanding Bathtubs
The standard tub drain works well for the drop-in, undermount and alcove tub installations. But when installing a stand alone bathtub (freestanding), obstacles can make putting the p-trap near a wall difficult or impossible. With a direct drain bathtub, the drain pipe connects to the p-trap directly below the drain at the bottom of the tub. Keeping in further from the bathroom wall.
This is a drawing from MTI Boutique Collection Installation Manual. The majority of these tubs have an integral slotted overflow & direct drain. See All Freestanding Tubs. Another option is a freestanding tub with an above floor rough-in. Either way, add a Quick Connect or Island Drain and your plumber’s job just got much easier!
Along with the popularity of freestanding tubs has come the availability of integral overflows. This is usually a long, thin style overflow. It allows the tub to have a direct drain whether it is a freestanding, drop-in, undermount or alcove tub. With this modern overflow (and higher water level) comes the necessity of a direct drain. There is a channel built into the tub so the water flows from the overflow to the drain.
This is a popular option with many of our bathtubs.