The thin layer of organic sludge that lines your drain acts like a sponge. It holds moisture against the pipe wall. When freezing starts, that sludge creates a rough surface for ice crystals to latch onto. Within a few hours of your morning shower, a partial blockage can turn into a full ice dam.

If your drain is frozen, you can often clear it using household items. to thaw a pipe, as this is a fire hazard and can damage modern PVC plumbing. 1. The Salt & Boiling Water Method

Recognizing the symptoms early can prevent a full pipe burst. Common indicators include: