This article is by theplumber.com
So you think you have a leak. Maybe it’s obvious, maybe it isn’t. Are you just being paranoid? Let’s try to find out.
If you’ve noticed disturbed dust patterns that look suspiciously like a dirty car after the rain has dried, we would agree that there’s been water disturbing that dust at some point. Whether the water was from an open window during the rain, a leaky supply line, or a kid with a spray bottle… well, that’s harder to tell.
Naturally if you see water, just follow the drips, turn off the nearest shutoff valve, and either fix it or call your plumber. But if there’s no water now – just dusty evidence – you still might be able to find the leak.
Water follows the path of least resistance. There’s a pretty good chance if you found evidence of a leak (and it hasn’t been fixed), that water will travel that way again. One trick to help find where the drips are dropping from calls for a paper towel or paper bag. This is a useful trick in rental homes, especially when you’ve just moved in (since a leak may have been fixed, but the cleanup job may not have been too great). Grab a paper towel, a paper bag, or even a newspaper and put it under where you suspect dripping. If a drip falls, it will leave a spot, which should help you find where the drip originated. You can also try making an ink grid on the paper using some sort of non-permanent marker to make any drips more obvious.
If there are supply lines or appliances around the suspect area, check them carefully for rips or splits, unattached hoses, or anything else that looks like it could cause a leak. If all looks right, turn on the water (or water-using appliance), making sure you can turn if off again quickly just in case. Check for leaks (you may need to wait a few minutes), and turn everything back off. If you see drips on your paper, put a bowl or bucket to catch the water, then trace that drip back to where it came from. Once you know what’s leaking, you can fix it yourself or call your landlord and/or plumber and let them know what you found (and how you found it).
If you see nothing at the time, it might just be a really slow leak. Check on it daily or more often to see if drips fall when you’re not looking. If you have no drips after a week or so, the leak might have been taken care of, or it might have been that kid after all. Or maybe it only appears when it rains. We offer a terrific assortment of water alarms if you want to be notified exactly when the leak reappears. Either way, still check every so often, and mention it to the professionals the next time you see them.
Please keep in mind that just because you cannot identify a leak yourself, doesn’t always mean you don’t have one. Listen to your gut and look at the evidence. If you feel something isn’t right, your water bill suddenly shoots up, your water meter seems to be running a marathon, or you hear running water when nothing is on and can’t find the reason, don’t wait, call your trusted local plumber right away! Not all leaks are easily visible, or leave obvious clues. Some leaks, like ones under a home, may manifest as a warm spot under your feet that hasn’t been there before, or a yard that suddenly has squishy places (possibly broken sprinkler pipe, but also a potential septic issue). These sort of leaks require a licensed plumber quickly.