The 10-Minute Monthly Leak Inspection
Ten minutes a month, a torch and a hand. This routine catches the leaks that would otherwise run for six months inside a wall.
Once a month, check under every sink for damp or corrosion, look behind the refrigerator at the ice-maker line, inspect washing machine hoses for bulges, and glance at the water heater base for rust or moisture. Then read your meter with everything off. Five minutes covers the four components responsible for most residential water losses.
Every expensive water loss we attend that was not sudden had a period where it was small, findable and cheap to fix. Nobody looked.
This is the routine. Ten minutes, once a month, with a torch and the back of your hand.
Under every sink — two minutes
- Run the back of your hand along the supply lines and the trap. Damp is damp even when nothing is visibly dripping.
- Look at the angle stops for green corrosion, white mineral crust or staining.
- Check the cabinet base for water staining, swelling or a lifted edge — the base tells the story even when the leak has dried.
- Look at the underside of the sink bowl for condensation or corrosion at the fittings.
- Run the tap and the disposal briefly while you are looking.
Every toilet — one minute
Feel the floor around the base for softness or movement. A toilet that rocks slightly has a failing wax seal, and that leaks into the subfloor rather than onto the floor.
Check the supply line and the angle stop for damp and corrosion. Then, twice a year, put a few drops of food colouring in the cistern and wait twenty minutes without flushing — colour in the bowl means the flapper is passing water continuously.
The water heater — one minute
- Look at the floor around the base for staining or damp. Any water at the base of the tank body means corrosion through the vessel — replace it now, not next month.
- Check the connections at the top for corrosion or mineral crust.
- Look at the temperature and pressure relief valve and its discharge pipe for signs of recent discharge.
- Check that the seismic strapping is present, tight and anchored into structure.
- Note the age from the data plate. Past ten years in this water, plan the replacement.
Washing machine and dishwasher — two minutes
Pull the washing machine forward far enough to see the hoses. Look for rust at the crimped fittings, bulging, or any weeping. Check the date on the collar if there is one — over five to seven years and they should be replaced regardless of appearance.
For the dishwasher, take the kick panel off once a year — usually two screws — and look and feel underneath. Water sitting on the subfloor under a dishwasher is invisible from the kitchen and extremely common.
Ceilings, walls and floors — two minutes
- Scan ceilings, especially below upstairs bathrooms and laundries, for new staining or a change in texture.
- Look along wall bases for baseboards separating, paint bubbling, or drywall that feels soft to a firm press.
- Walk barefoot across tile and concrete floors. A warm patch is a hot-water slab leak until proven otherwise.
- Check for flooring lifting, cupping or sounding hollow underfoot.
- Look at ceiling areas around can lights and fixtures, where water collects first.
Outside — two minutes
- Walk the perimeter looking for damp ground, soft patches or a strip of lawn greener than the rest.
- Check every hose bib for drips and for damp at the wall behind it.
- Look at the irrigation backflow assembly for weeping.
- Check that area drains are clear while you are out there.
- Look at the meter box — standing water in it can indicate a service-line leak.
And once a quarter: the meter test
Turn off every tap and appliance that uses water, note the meter reading including the small leak indicator, wait fifteen minutes with no water use, and read again.
Any movement means water is escaping somewhere. It is the single most definitive test available and it takes fifteen minutes four times a year.
While you are at it, compare your consumption history against the same period last year. A step up that stayed up is a leak; seasonal variation goes back down.
Frequently asked
Is monthly really necessary?
Monthly for the two-minute cabinet checks, quarterly for the meter test, annually for the dishwasher kick panel and the refrigerator. The point is regularity rather than intensity — catching a weep at week two instead of month six is the entire value.
I found damp under a sink but no visible drip. What now?
Dry it completely, put a paper towel underneath, and check again in twenty-four hours. Damp again means an active leak. Then check whether it is the supply, the trap or condensation on a cold line — all three are cheap fixes and all three cause real damage if left.
What if I find a warm spot on the floor?
Treat it as a slab leak. Do the meter test, and call for detection. In a Mission Viejo home of 1960s to 1980s vintage with original copper, a warm patch on a hard floor is a hot-water slab leak far more often than it is anything else.
Expert insight
The meter test settles most questions
Shut every fixture in the house, note the meter reading, and come back in fifteen minutes. If it has moved, water is going somewhere. It is free, it takes almost no effort, and it is the fastest way to turn "I think something is wrong" into a definite answer — which is exactly the point at which a slab leak is still cheap to deal with.
The bottom line
Under the sinks, round the toilets, at the heater, behind the appliances, along the wall bases, and outside. Ten minutes.
It is the cheapest thing in this entire trade, and it catches the leaks that would otherwise become rebuilds.