When you have a plumber remove all of your old pipes in the kitchen and replace them with modern pipes, you expect to go without a leak for a long time. When you begin to experience a leak not more than a few weeks later, there is definitely something wrong. However, it may not be the plumber's fault or the new pipes may not be to blame. Before tempers flare, try to determine where the leak is coming from. Here is how.
Grab a Flashlight or Trouble Light
Grab a flashlight or a "trouble" light and sit in front of the area that appears to be leaking. Anywhere there is exposed pipes and plumbing, like under a sink, is a good spot. Take everything out of cabinets to see inside. Then hold the light so that it shines on all the plumbing, hoses, exposed pipes, etc.
Watch and Listen for Five Minutes
Watch and listen for five minutes. If anything just leaks without turning on the sink or appliance, you should be able to hear it drip and/or see it leak. If nothing is dripping or leaking after five minutes of watching and listening, you do not have any leaks as the result of water sitting still in the pipes.
Turn on a Faucet or Appliance for Two Minutes and Watch Again
When you have a faucet turned on, you will not be able to hear dripping, but you can still see it. Turn on one faucet and watch for two minutes. If you do not see a leak or drips, turn that faucet off and turn the other one on. (If you only have a single faucet, turn it all the way to hot, then off, then turn it all the way to cold for this exercise.) Watch for leaks and drips. If you still do not see any, an appliance, such as a dishwasher, may be at fault.
If you do see drips with either faucet turned on, look to see where it is leaking. Sometimes leaks are as simple as loose connections between water supply hoses and the undersides of the faucets. It may also be a leak in your new plumbing, but you should still verify where the leak is coming from.
No Leaks under the Sink? Try the Dishwasher
Finally, if you see no leaks coming from the new plumbing, and no leaks coming from faucets when you turn them on, start the dishwasher instead. You would be surprised to learn that many dishwashers tend to have hoses that loosen up, and then you get a gush of water everywhere. If the dishwasher is the culprit, you will have to have the plumber return and fix it.