Dry Finger Testing Might Seem Silly but is Very Important

The Dry Finger Test Can Help You Before and After You Call a Plumber (Note: More details available in the book OnlinePlumbingAdvice.com)

Mike Quick uses his forty years of experience to help you avoid costly mistakes

As silly as it might seem, details are especially important when testing or searching for a leak. Cold can feel wet. Small streams that provide major leaks can hide in areas that make them difficult to see. Extremely fine squirts that look like a cobweb, small drips, and many other difficult to find leaks can be found using the dry finger test. Learning the dry finger test is one of the most important steps to learn before you start searching for leaks. Searching for leaks before and after you call a plumber can save you lots of money, aggravation, and time. More importantly, it should help provide a sanitary living environment for your family.

How to Do the Dry Finger Test

After you make sure a finger is completely dry, touch completely around a joint, a pipe, or any surface area that you want to test. Only touch one area at a time. Immediately after touching each surface, closely inspect the dry finger for any trace of water. Always be careful of sharp or pointed surfaces that could cut or puncture you.

When I try to explain this important technique to most people, they seem to think I am crazy or that I think they are stupid. Often, people don’t understand how important this type of detail is until I demonstrate on the job. Frequently, water runs down the back side of a pipe or otherwise goes unnoticed until careful testing with a dry finger reveals its presence. Sometimes people carelessly contaminate a test area by trying to test too much too fast. The dry finger test provides a way to carefully test one joint, one pipe, or one surface at a time. When I mention testing with a dry finger, I am referring to the dry finger test.

Leak investigation is similar to other types of investigation.

  • Gather as many facts as possible.
  • Try to determine what took place when the leak started.
  • Determine if the leak seems to be getting worse or better. Often when I talk to people on the telephone, I ask them to count seconds between drips and try to establish if the drips are getting faster, slower, or, staying the same.

If there is a steady drip (staying the same) sometimes turning the water off the whole house and opening a faucet on the lowest floor (to drain the water) is a good idea. If having the water off seems to clearly affect the leak, there is a good possibility that a water pipe or water pipe connection is leaking.

It is important to check exposed areas very carefully before anyone starts cutting holes in the wall or ceiling. Often it is almost impossible to see leaks that run down the back of a toilet, the back of a supply line, or other surface. If you carefully work a dry finger completely around the back of a toilet, the back of all supply lines, and other surfaces, sometimes, you will find a leak. Do not attempt to feel a leak; each time a dry finger is used to test a surface, the dry finger must be carefully examined for any trace of water. Properly checking for a leak at upper levels is important. Learning to properly test with a dry finger might seem silly, but it is one of the most important things to learn.

Testing a Sink for Leaks to the Floor

With a dry finger, check to see if any supply lines, shut-off valve, or any other surfaces have any trace of water; carefully examine your finger after each surface is touched. It is especially important to make sure the back side of supply lines and other surfaces are tested. Always remember to carefully establish the highest surface that fails the dry finger test.

Testing drain connections should be performed thoroughly and systematically:

  1. Run hot water in the sink until the drainpipe feels hot.
  2. Run cold water in the sink until the drainpipe feels cold.
  3. Dry finger test the upper portion of the drain connection (where the drain touches the sink) and proceed to dry finger test all drain connections (always test the highest areas first).

About the Author

Mike started his plumbing apprenticeship in 1969. He has over forty years experience solving plumbing problems in homes. Mike helps people avoid mistakes. He is the founder and president of Quick Quality Plumbing Inc.. Mike published a book (OnlinePlumbingAdvice.com) and he is the administrator for the web site (OnlinePlumbingAdvice.com.)