Find it before you open anything

The meter test settles it on municipal water. Turn off every fixture and appliance that uses water, note the meter reading or watch the small low-flow triangle, and wait two hours. Any movement means water is going somewhere. On a well, the equivalent sign is a pump that cycles on periodically when nobody is using water.

Because water travels. It runs along the top of a joist, down inside a wall cavity, and emerges at the first place gravity and a seam let it out, which is frequently several feet from where it left the pipe. Opening drywall based on a stain is how people end up with three holes and an unfound leak. Detection first, one hole second.

Acoustic listening gear that picks up the sound of pressurised water escaping through a small opening, thermal imaging that shows temperature differences from wet material or a hot line under a floor, moisture meters for confirming extent, tracer gas for stubborn cases, and pressure isolation testing to work out which part of the system is losing water. Most jobs use two or three of these rather than all of them.

Yes, and that is one of the main reasons this service exists. Slab leaks are located acoustically and thermally from above, with the system isolated and pressurised so the escaping water makes a signature that can be traced. Once located, the repair options are a spot repair through the slab or a reroute around it. See slab leak repair.

Usually into the ground, where it leaves no trace you would notice. The service line between the meter and the house is a common culprit, as is a crawl space pinhole dripping onto soil. Indoors, a toilet flapper that seeps continuously into the bowl is the classic silent water waster and can account for a startling volume without ever making a sound.

Not necessarily, which is why bills are a lagging indicator. Depending on the billing cycle you might be two months into a leak before the number looks wrong. If your bill has jumped, the leak has probably been running longer than you think, and that changes what the damage assessment looks like.

Usually there is a diagnostic charge that covers the time and equipment, and it is often credited against the repair if you go ahead the same day. You should be told which arrangement applies before anyone comes out, not after the leak has been found and you are in a weak negotiating position.

Most residential jobs are one to three hours, depending on how large the property is and how many potential sources have to be eliminated. Isolating sections of the system is often the slow part, particularly in a house with no valves in useful places, which is common in older Virginia homes.

Locating it, yes. That is the point of non-invasive detection. Repairing it usually needs access. The value of detection is that it turns "open the ceiling and see" into "open twelve inches of ceiling at this exact spot", which is the difference between a small repair bill and a large one.

On municipal water, the utility is generally responsible up to the meter and the homeowner from the meter to the house, so a leak between the street and the meter is usually the utility’s to fix. Establishing which side of the meter the loss is on is part of the diagnostic, and it is worth knowing before anyone digs up a yard.