Burst pipe repair, water stopped first, cause found second

Stop the water first

Nothing on this page matters more than closing the main. A half-inch supply line at normal household pressure discharges somewhere in the region of five to eight gallons a minute. That is several hundred gallons an hour going into your floors, and the difference between a two-thousand-dollar problem and a thirty-thousand-dollar one is measured in how long it runs.

• Find the main shut-off, typically the basement wall on the street side, near the meter. Turn clockwise until firm, or a quarter turn if it is a lever.
• Open the lowest cold tap in the house to drain down the standing water in the system.
• If water is near electrics, kill the affected circuits at the panel, but do not stand in water to reach it.
• If the burst is on a heating pipe, switch the boiler off at its service switch as well.
• Photograph everything before you move or mop anything.
• Then call.

Why pipes burst

Freezing is the dominant cause here between December and March. Ice expands, the pipe splits, and the split usually only starts leaking when the thaw arrives, which is why bursts peak a day or two after the coldest night rather than during it.

Corrosion is the slow one. Massachusetts has an enormous stock of pre-1960 housing still running galvanised steel, and galvanised rusts from the inside until the wall thins to nothing. It fails as a pinhole first, then as a split. Copper suffers its own version where water chemistry or stray electrical current pits the metal, producing the classic pinhole leaks that spray a fine mist for weeks before anyone notices.

Pressure kills pipework quietly. Municipal supply above about 80 psi stresses every joint in the building, and water hammer, the bang when a washing machine or dishwasher valve slams shut, sends shock waves through the system that eventually find the weakest fitting. A pressure-reducing valve and arrestors are cheap insurance.

Movement and age account for the rest: settling foundations, poorly supported runs vibrating against joists, botched previous repairs, and fittings that were marginal when they were installed forty years ago.

What the repair involves

Once the water is off, the plumber isolates the affected section, ideally at a valve close to the failure, so the rest of the house keeps running while the work is done. Then the failed length is exposed, which sometimes means opening plaster or lifting boards. A good plumber opens the smallest hole that lets them work properly and tells you before they cut.

The damaged section is cut out well beyond the visible failure. This matters: a freeze split is often longer than it looks, and corrosion is never confined to the hole you can see. Replacing six inches around a two-inch split is how you end up doing the job twice.

The new section goes in using an appropriate method for the material, soldered or press fittings on copper, appropriate transitions where materials change, proper support and clearance so the new run is not resting on a joist edge. Then the system is repressurised and watched, because the moment of highest risk for a system that has been drained and refilled is the first ten minutes back under pressure.

Repair or replace the run

The judgement call on any burst is whether to fix the failure or renew the run. One burst on an otherwise sound copper system is a repair. A third pinhole in eighteen months on the same galvanised line is a system telling you something.

Signs that point towards repiping a run rather than patching it: rusty or discoloured water, steadily falling pressure over years, visible green or white crusting at multiple joints, repeated leaks in different spots, and any galvanised system over fifty years old. Repiping a section is disruptive and costs more up front, but it ends the cycle of call-outs and the compounding damage that goes with them.

A plumber worth using will tell you honestly which situation you are in, including when the answer is "this one repair will hold for years, leave the rest alone."

Hidden bursts and what they cost

The worst bursts are the ones nobody sees. A split inside a wall cavity, under a slab, or in an unvisited crawl space can run for days or weeks. The classic signs are a water bill that jumps without explanation, a warm patch on a floor over a hot line, a musty smell with no visible source, staining or bubbling paint on a wall, and the sound of water running when nothing is switched on.

Where the leak is hidden, finding it precisely before opening anything is the whole game, acoustic equipment, thermal imaging and tracer methods locate it to within inches. That work is covered on our leak detection page and it is almost always cheaper than exploratory demolition.

Unoccupied properties are the extreme case. A burst in a closed-up second home on the Cape in February, discovered in April, routinely writes off ceilings, floors and cabinetry throughout a building. If you own a property that sits empty, a leak alarm and a remote temperature sensor cost less than a single night of that.

Insurance and documentation

Most Massachusetts homeowners policies cover sudden and accidental water damage from a burst pipe. Most exclude gradual leakage that has been going on unnoticed, and many exclude freeze damage in a property that was left unheated and undrained.

What helps a claim: photographs taken before any cleanup, the plumber's written description of what failed and why, an itemised invoice separating emergency call-out from repair, and dated records of any maintenance you had done. What hurts a claim: tidying up first, a vague invoice reading "plumbing repair", and no evidence the property was being maintained.

We do not file claims on your behalf. What we do is make sure the contractor documents the failure properly at the time, because reconstructing it afterwards is much harder.

Related: frozen pipe repair for the cause behind most winter bursts, and pipe insulation for stopping the next one.