The leak disappears before anyone can see it.

Record the event, not an assumed explanation

Write down the date, approximate time, affected location, and whether water was actively moving or only visible as dampness. Include fixture or appliance use you actually observed. “Wet after the washer drained” is useful; “washer pump failed” may be an unsupported conclusion.

One or two clear photographs can preserve the location and scale. Keep the originals rather than applying filters that change color or contrast. Include a wider view so the provider can orient the detail. Do not post utility account numbers, door codes, residents, or other private information in a public gallery. This site has no upload form; share needed evidence directly with the verified recipient.

Delayed appearance can complicate the timing

Water may take time to travel through a concealed route before it becomes visible. A drip noticed after a fixture has stopped does not necessarily mean the idle fixture is continuously leaking. Likewise, a stain found in the morning may have begun during an earlier use. Record what is known and what happened outside your observation window.

Tell the provider about long gaps when the room or property was unoccupied. If several people use the plumbing, ask them for relevant observations without turning the household into a testing crew. The goal is an accurate history, not a perfectly complete diary that delays needed attention.

Automatic equipment may be part of the sequence

Appliances and other water-using systems can operate without someone standing at the fixture. Mention a dishwasher, refrigerator connection, laundry machine, irrigation system, or other known equipment in the relevant area. Do not disable protection devices or alter programming just to force a leak to appear.

If the suspected pattern relates to a cycle, use existing controls only as directed by the manufacturer or the professional planning the investigation. A plumbing provider may need to coordinate with an appliance technician for an internal equipment issue. Confirm who owns that question rather than assuming every water-related component falls within one visit.

Agree on the investigation's stopping point

Ask what the provider proposes to check during the first visit and what evidence would justify access or repair. If the symptom cannot be reproduced safely, there may still be useful observations to make. Ask how those findings will be documented and what a further visit would cost if the source remains uncertain.

Be wary of both extremes: certainty from a single ambiguous photograph and a promise that no work can begin until you recreate the leak yourself. The professional should explain a reasonable investigation plan and its limits. You should understand whether the charge covers observation, testing, exploratory access, or a particular repair before authorizing it.

If the provider proposes leaving a temporary monitoring device, ask who supplies it, who checks it, and how you will know a result needs attention. Do not assume that a device left onsite is connected to an actively staffed response service or will automatically arrange another visit.

Pressure and temperature are questions, not remote diagnoses

If leakage seems linked to hot-water use, a recent pressure change, or a particular operating condition, share that sequence. It may affect what the provider measures. The sound of water, a weak faucet, or a warm surface is not enough to establish a pressure or temperature-related fault.

Do not adjust regulators, safety valves, or heater controls to see whether the symptom disappears. Ask what measurements are appropriate and how they will be interpreted alongside the leak evidence. The pressure discussion guide helps separate actual readings from the everyday impression that water feels stronger or weaker.

Preserve a useful result even when the source remains uncertain

A first visit may identify a defect, narrow an area, or rule out a specific condition during the time observed. Ask for the distinction in the written findings. A lack of leakage during one test does not certify the property free of intermittent problems, while a suspected area is not the same as a confirmed broken pipe.

If monitoring is recommended, agree on what to observe, what condition means stop using a fixture, and whom to contact. Do not accept open-ended instructions that leave a hazardous active leak unaddressed. If a repair is made, keep the original pattern with the component description so a recurrence can be assessed against the right history.

For a leak that comes and goes, call 877-702-1610 and lead with the most recent event. Confirm the answering provider and its diagnostic scope, address coverage, and charges. Portland Leak Notes is an independent referral website; it does not promise that a source will be found in one visit or that a particular testing method will avoid all access work.