Most leaks in home drains can be repaired easily, although some can be symptoms of more serious problems. Most leaks occur in drains under kitchen or bathroom sinks. Here’s how to locate and fix them like a pro.
Water on the shelf under the sink is an unmistakable symptom of a leak.
The most common reasons are the connections under the sink, or between double sinks, or cracks in the drainpipes. All can be fixed easily and inexpensively.
The first step is to inspect connections. There are three of them. Look for watermarks, i.e., mineral deposits, which are signs the connections are leaking. This may result from improper installation, or the vibrations from constant use over time have loosened these connections.
The first connection is the drain attached to the bottom of the sink. It should have been installed with rubber, vinyl or paper washers or plumber’s putty. On most sinks, the drain is held in place with a large brass nut that fits over the threaded metal bottom of the drain extending below the sink.
Second, the bottom of this drain fits into the top of an s-shaped pipe, known as a “P” trap, which contains a small amount of water to block sewer gas from coming into the room.
The connector to the “P” trap is a nut, usually PVC (plastic), with a flexible collar inside it that tightens onto the bottom of the drain from the sink forming a watertight seal.
The downstream end of the ‘P’ trap is the third connection to check. The end of the ‘P’ trap fits onto a vertical pipe. This pipe is both the vent (called the stack) that extends upward from the connection, and the drain that extends downward through the floor beneath the cabinet to the sewer.
This end of the “P” trap is also secured using a PVC connector with a plastic nut that has a flexible collar inside. It tightens onto the connection to the vent/drain pipe, forming a water-tight seal.
Any of these connections that show signs of water leaks may have loosened over time, or were not tightened enough when installed, allowing water to seep out. Tightening the connection usually solves the problem.
To tighten the connections, turn the connector by hand until firm, and then turn it slightly more with up to a further ¼-turn, using water pump pliers, an adjustable wrench similar to a light-duty pipe wrench. Be careful to not over-tighten.
Sometimes, simply tightening a connection may not stop the leak. In this case, mineral deposits from leaking water may be at fault. The leaky connection should be disassembled and cleaned. If the threads are coated with mineral deposits, soak the connections in white vinegar or a commercial mineral deposit cleaner, then use a stiff cleaning brush.
A more difficult leak to fix may be caused by connections that were not properly aligned or cross-threaded when originally installed.
Misalignment sometimes can be corrected by loosening the connections, then rotating the ‘P’ trap slightly both ways until a better alignment is found. If that does not solve the alignment problem, it may be necessary to rework the plumbing – a job for an experienced handyman or plumber.
If cross-threaded, try unscrewing the connection and reattaching it carefully while trying to keep both parts aligned. Applying Teflon tape can help to lubricate the threads and also may coat damaged threads enough to stop a leak. If that fails, the assembly should be replaced.
Another source of leaks is cracked drainpipes. Cracks can appear years after installation. The pipes may have been cracked during installation but took years of shrinkage or vibration from use to begin leaking.
A frequent location of leaks is the drain link between double sinks in kitchens or bathrooms. Usually, one sink drains toward the other, which has the connection to the “P” trap and the sewer system. Leaks in the link can be fixed easily in a couple of ways.
Significant leakage means the section of drainpipe should be replaced. The first thing we do here at Houston house buyers is to cut out the cracked section. Then cut a section of new pipe of the same diameter slightly shorter than the length of the cracked piece removed. Cut out only as much as necessary to remove the damaged portion. Use some medium grit sandpaper to clean off burrs from sawing on the existing pipe ends and the new pipe.
Next, slip couplers of the same diameter on both cut ends of the existing pipe. Sometimes couplers have a ridge inside at the middle to help center the coupler on the pipe. This ridge must be removed for the coupler to slip all the way past the ends of the remaining edges of pipe. This is necessary to accommodate the repair length of pipe.
Use a curved or round wood file or rasp to remove this ridge. Then slip on the couplers and dry-fit the repair piece to ensure a proper fit. Glue the couplers and repair piece in place following the instructions on the adhesive container, available where the repair pipe was purchased.
Sometimes, small cracks in drainpipes can be repaired with a good quality repair cement or, better yet, a self-adhesive pipe wrap. Several pipe wrap products are available.
One of the best is a product called MagicWrap™, made in England by Glasgow Manufacturing, and available in most home improvement stores here. It is a rubber-based product that appears to fuse to itself and to surfaces to which it is applied, forming a solid repair.
The manufacturer claims it can withstand pressures of up to 100 pounds per square inch (PSI), so should be suitable also for repairing holes and cracks in most garden hoses and home irrigation systems. Be wary of attempting to use it to repair leaks in hot and cold water pipes.