A parcel can have road access, utilities nearby, and zoning that allows exactly what you want to build — and still not be buildable, because the soil won't absorb wastewater the way a septic system needs it to. If there's no public sewer line, septic isn't optional. It's the only way to handle wastewater, and not every piece of land can support one. That's where a perc test comes in. Here's what it actually measures, why some lots fail it, and how to find out before you're un