Water leaks under the sink can be from the drain or from the water supply lines. Either way the smart thing to do is shut the valves off under the sink, place a small container under the leak to catch the water. If the water is really cold it may be coming from your air conditioner condensate drain line that is often connected to a sink drain. If that is the case you may want to turn off your air conditioner also. Once you have the leak contained call Benjamin Franklin Plumbing we will get a Ben Franklin Plumber out to your home as soon as possible. Before any further water damage can occur.