Abstract: The present invention provides a new waterfall apparatus water reservoirs such as pools, spa's and the like. It comprises a manifold having a water inlet connected to the a water supply, preferably the water supply from the reservoir's plumbing. The manifold has internal baffles to remove turbulence from the water, which is then directed to a spillway water outlet. The spillway has a through slot that allows water to flow out from the manifold. It also has a removable outlet cap which forms the water into a particular waterfall shape. Another embodiment of the invention for spas, has a tubular body and a outlet that is in the form of a longitudinal slot in the body. The outlet cap is then mounted in the slot. In both embodiments the outlet cap can be easily removed to clean the apparatus if debris becomes lodged within it. It can also be removed if the spillway becomes damaged or it the pool/spa owner would like to change the type of waterfall produced by the apparatus.