When your home water heater fails or you're deep in the backcountry, this simple and effective gravity-fed shower can make a world of difference. The black vinyl absorbs sunlight to warm water naturally, making it perfect for outdoor use or as an emergency backup. We used this exact shower for over two weeks for a family of four—it works. Compact enough to store in a bug-out bag or car kit, but big enough to provide multiple washes.