3 Steps to Locating the Source of a Sink Leak

Posted on: 27 April 2017

Leaks under the sink may go undetected for a long time because pipes are usually hidden within some hardly-ever-used cabinet. By this time, your cabinet space could have become a hot mess that's expensive to fix, not to mention the amount of water wasted during the leak. As such, it is advisable to go through your cabinets routinely so that leaks and ensuing water damage are nipped in the bud. The hardest part of sorting out a leak is finding where it comes from. Once you find it, you'll know whether you can easily fix it or you need professional assistance. This article discusses three common leak origins and how to pinpoint them.

1. Supply/shutoff valve

This is the most common source of leakage. The supply is the tubing that connects your sink to the main water supply pipes. For many sinks, supply tubes are fitted with shutoff valves and fitted onto the main pipes. To identify a leak from here, use a paper towel to wipe down the supply tube, shutoff valves and any other connections. If the paper comes out wet, this is where the leak comes from. Fixing such leaks is often as simple as tightening a nut on the valve. If after tightening the compression and packing nuts the leak persists, the valve may need replacement. Turn off the main supply point to avoid wasting water and then call in an emergency plumber.

2. Drains

These are the second most common sources of sink leaks. To identify a drain leak, open the water faucet with the stopper connected so that the sink fills up. Remove the stopper and then inspect every inch of the U-pipe that leads from the drain to the wall, paying attention to the joints. Alternatively, you can use a paper towel as above. Once again, fixing this leak could be as simple as aligning and tightening the slip joint properly. If the leak persists, place a bucket under the sink and then open the joint up completely. Use pipe putty to create a seal around the washer. If you pinpoint the basket strainer as the source, also try tightening and use pipe putty as described above if tightening doesn't work.

3. Sink base

It is possible for water to leak from the rim (upper part of sink basin) onto the countertop and into the cabinet. This can cause extensive water damage to the countertop and cabinet if left unchecked. To identify a leak here, spill some water around the rim and check whether any of it spills onto the countertop. If so, you'll need to remove the old caulking and apply a new one. All a plumber to avoid messing this up further.