How do public water pipes not freeze in very cold weather? If house pipes freeze easily when there isn’t enough heat to keep the water in a liquid state, then why don’t pipes under the street freeze?

Question

How do public water pipes not freeze in very cold weather? If house pipes freeze easily when there isn’t enough heat to keep the water in a liquid state, then why don’t pipes under the street freeze?

In: Engineering

Answer 1

They are buried below the frost line. They are kept deep enough that the radiant heat of the earth keeps them above freezing. This is usually about 4 feet deep as a decent safety margin in the lower 48, not sure about Alaska though, I bet they go deeper.