How Frozen Pipes Become Burst Pipes — and How to Prevent It

By Eagle Plumbing · October 28, 2026

Maryland winters don't have to mean burst pipes. Understanding why pipes freeze — and the five causes behind almost every case — makes prevention simple.

It's the pressure, not the ice

When water freezes inside a pipe it expands, but the ice itself usually isn't what splits the pipe. As the frozen section grows, it traps water between the ice and the closed faucet, and the pressure in that trapped section climbs until the pipe wall or a joint gives way. That's also why the flood often starts when things thaw — the crack was already there, waiting for water to flow again.

The five usual causes

Almost every frozen-pipe call traces back to one of these: a sudden hard freeze; poor or missing insulation; pipes running through exterior walls or crawl spaces; unheated basements, garages or attics; and lines with little or no water flow. Homes in Beltsville and across the DMV hit several of these at once on the coldest nights of the year.

Prevention that actually works

Insulate exposed pipes before winter, especially in crawl spaces and exterior walls. Keep a slow drip running on vulnerable lines during hard freezes. Open cabinet doors under sinks on exterior walls so warm air reaches the pipes. And know where your main shut-off valve is — if a pipe does burst, shutting the water off in the first minute is the difference between a repair and a restoration project.

Already frozen? Already burst?

If a fixture gives no water or only a trickle, a pipe may be frozen — call before it becomes a burst. If you find a split pipe or active leaking, shut off the main valve and call us. We control the water, locate all the damage (nearby sections are often stressed too), and repair or replace the damaged section properly — no temporary patches.