A drain trap includes an outer part including a circumferential wall, the outer part extending in an axial direction between an outer part upper end and an outer part lower end, the outer part including outer part radial threads proximate the outer part upper end, the outer part lower end forming a well configured to trap and retain fluid, the outer part further including at least one opening disposed in the circumferential wall, an inner part, and a flat disk structure retained within the well. Fluid entering the drain trap accumulates in the well, and the fluid entering the drain trap is expelled from the drain trap through the at least one opening disposed in the circumferential wall.

A drain trap assembly comprises an upper housing and an access fitting removably attached thereto. The upper housing includes a main body defining an open bottom end, an inlet pipe extending through the main body in a vertical direction and exiting through the open bottom end, and an outlet pipe extending from an annular sidewall of the main body. The access fitting is removably attached to the main body for selectively covering the open bottom end and defines a fluid reservoir in communication with the inlet pipe and the outlet pipe.

A drain trap assembly comprises an upper housing and an access fitting removably attached thereto. The upper housing includes a main body defining an open bottom end, an inlet pipe extending through the main body in a vertical direction and exiting through the open bottom end, and an outlet pipe extending from an annular sidewall of the main body. The access fitting is removably attached to the main body for selectively covering the open bottom end and defines a fluid reservoir in communication with the inlet pipe and the outlet pipe.