The water draining and collection system for monocoque vehicles applied with tonneau cover or similar object of present invention is aimed to solve the drawbacks described in the prior art through a water collection system for monocoque vehicles applied with tonneau cover or similar comprising a set of rails (10) and (20) of specific shape positioned on bed side and front faces between the plastic finishes (101) and (102) e bedliners (100) avoiding water intake and improving the draining system. This new embodiment applied in the water collection system allows an easy deployment and application in any bed monocoque vehicle model, efficiently solving the problem of water intake and assuring a better water draining.