You might be wondering if your garbage disposal, kitchen faucet or pipes under your sink is leaking if you open up your kitchen cabinets and find soggy paper towels, or drops of water .

A large leak is often obvious by the amount of water in the area or signs of erosion. It may not be easy to identify a small leak. There may be water from the leakage on multiple parts that aren’t leaking.


It is important to prepare the area properly and create a baseline before diagnosing a serious leak. To make sure you have enough space to see everything, remove everything from under the sink.

You will need to place your hand underneath the cabinet to be able to see the sink basin. The next step is to grab a flashlight and some dry towels.

Use a dish towel or a few paper towels to dry everything thoroughly. Dry the garbage disposal, drain pipes and shutoff valves. To absorb water from the corners of your paper towel or rag, use the corner of the towel.

This will give you more information about the source of the leak. You may see a spot where the water is coming back as soon as it is dried. If this is the case, you have a leak. If that is the case, then proceed to step 2.


After drying everything, test the drain pipes. The majority of kitchen sink leaks occur in the drain lines. This is often due to loose or incorrectly connected slip joints. These won’t appear unless there is running water.

Run water in each of the sink basins. Allow it to run for 2-3 minutes in each basin. Afterwards, use a flashlight and dry tissue paper/paper towel to check for leaks.

Begin at the highest point where pipes/disposal connect with the sink basin(s). It is important to be attentive to detect a leak as soon as it occurs. It may be difficult to see where the water is coming off if you wait. Feel for water in places that are hard to see.


If there was no evidence of any obstruction during the regular flow test it’s time to stress-test the drain pipes. Fill each basin with water and place a stopper inside.

This is called the ” basin testing”. After the basins have filled, remove the stoppers from the drains and allow them to drain simultaneously. While the sinks are draining, run the garbage disposal . This places all drain pipes under the greatest stress they will experience during normal usage. Observe all pipes and garbage disposal while this is occurring.

If nothing is still visible, restart the dishwasher. Allow the dishwasher to run for a while, allowing water to fill up. Next, press the ” cancel/drain button (each dishwasher offers a different method of initiating the drain cycle manually).

The water from your dishwasher will likely drain into your garbage disposal at its top via a black or a white pipe. The water should be coming out of the disposal. Some setups allow water to flow through an ” Air gap”, which is located on the countertop near the faucet. This is also worth a look.


After performing the basin test, draining the dishwasher and checking for leaks, still have not found the source of the leak. Grab your flashlight and check the shutoff valves as well as the supply lines one more time.

It is possible that the leak was not detected on the first pass, as you were drying everything. You should look for signs of white mineral buildup on the hardware.

The faucet should be put through the same rigorous testing as the drain pipes. It can be turned on and off several times by moving the handle in different directions. As you do this, move the spout back and forth.

You can pull out the sprayer multiple times to run it through various modes. While you are doing this, check for any signs of moisture underneath the cabinet. Some faucets only indicate a leak if they are operated in a specific way, or if their spouts are in a particular position.


If the tests do not reveal anything, it could be that there is an intermittent leaked. It is better to watch it for a while than trying to guess and replace unnecessary parts.

You can use two to three baking trays to cover the plumbing underneath the sink. Rubber trays are also available.

All of your cleaning products should be returned under the sink. After heavy usage , check it every now and again. You can continue the troubleshooting procedure above if your cleaning supplies or baking tray is wet. Your cabinet will be protected from any water damage by the catch pan.

You can also buy a water alarm. This battery-powered device will detect any water in the cabinet and sound an alert. Some even have the ability to connect to your Wi Fi and send you a notification if they become wet. You can keep one of these under your kitchen sink, and another in the hot water heater drain pan.