Hefty Trash Compactor bag 18 gallon

Not every piece of UL gear is purpose-built for hiking — the Hefty 18-gallon trash compactor bag is a hardware-store item that became a staple pack liner through years of word-of-mouth in the ultralight community. At 68 L capacity and roughly 62 g, a single bag lines the inside of a backpack, keeping the contents dry even if the pack's exterior fabric or a non-waterproof cover lets water through during rain. The 2.5 mil polyethylene is considerably thicker than a standard kitchen trash bag, which matters both for puncture resistance and for how long it survives repeated stuffing and unpacking over a multi-day trip. It's not rated as fully submersible, so it's better thought of as protection against rain and splashes rather than something to trust in a stream crossing or prolonged dunking. Small tears or punctures can be patched with tape rather than requiring a replacement bag, and when empty it compresses down to roughly fist-sized, adding negligible bulk. It's a cheap, effective way to skip a dedicated waterproof pack cover.