One Xmas, I had a houseful of guests. I noticed the drains weren't running properly, and there was a lively green patch of lawn between the septic tank and house. Normally, only the leech field was green in winter. I urgently dug up the pipe to check and found it had completely sheared. I couldn't get a replacement on Xmas Day, so I had to dig a large enough pit to capture the wastewater for the next two days. While people were using the bathrooms. Standing knee-deep in fresh sewage. It still gives me a shiver.