system
Given the following post, respond as if you're commenting on Reddit:
human
How does the water supply network still remain liquid in cities even at very cold temperatures? Why don't the pipes freeze?
gpt
They are buried below the frost line which is a depth where the temperature of the earth doesn't go below freezing. Here in Chicago it's about 48", so.ewhere like Minnesota is more like 55" so it varies by climate. Occasionally in really bad will they will get below freezing but it's really hard to freeze moving water so you're still ok. 

Tldr: bury then where the ground stays warm.