One of the first questions we get from our customers who are interested in a tonneau cover is, “Are tonneau covers watertight?”, “Is this thing waterproof?”, or "Is there such a thing as a waterproof truck bed cover?". The short answer to this question is, when properly installed, a tonneau cover will keep the vast majority of water from entering your truck’s bed. To describe a tonneau cover as 100% watertight or waterproof would be inaccurate, but the most you’ll usually get are a few drops intruding during a rainstorm. A detailed explanation will give you a better idea of how much weather protection you can expect when you install a tonneau cover.
There are several different tonneau cover designs available on the market including soft and hard covers that open in a variety of different ways. Often times, the design of a tonneau cover will dictate the amount of water resistance you can expect. In the section below, we’ll examine and rank the water resistance of the most popular tonneau cover designs.
If your number one priority is keeping as much water out of the bed as you possibly can, a painted one-piece cover is the design you want. This cover consists of a single piece of fiberglass or ABS plastic that covers your bed from front to back, usually overlapping the tailgate and bed rails. This leaves the rear hinge as the only likely area where a small amount of water might intrude. UnderCover also offers gloss black versions of this cover design that are more affordable than comparable painted covers.