Dealing with a leaking or cracked PVC pipe under your sink is a common household issue that demands immediate attention. Left unaddressed, it can lead to water damage, mold growth, and a significant waste of water. While calling a plumber is always an option, this repair is often straightforward enough for a confident DIYer. This guide will walk you through the entire process of how to replace pvc pipe under sink, from turning off the water to testing your final connection.
Before you begin, it is essential to understand the layout of your under-sink plumbing. You will typically see a hot water line and a cold water line, both usually made of PVC or CPVC, connected to a small shut-off valve. These valves are your best friends for this project, as they allow you to isolate the water flow without turning off the main supply to the entire house. Knowing where these components are located will save you time and frustration once you get started.
Turning Off the Water Supply
The very first step in any pipe replacement is to stop the flow of water. Look for the two small lever handles or knobs located on the pipes leading to your faucet. These are the angle stops or shut-off valves. Turn them clockwise firmly until they are completely tight. To ensure you have successfully stopped the water, try turning on the faucet in your sink; no water should come out. If the valves are old and stiff, you may need to use a wrench, but be careful not to overtighten and damage the valve stem.
Removing the Old Pipe
With the water off, you can safely drain the remaining water from the lines by holding the faucet open. Place a bucket or a shallow tray beneath the pipes to catch any drips. Using a wrench, loosen the slip nuts connecting the PVC pipes to the valves and the drain assembly. You may also need to loosen the mounting brackets that hold the pipes in place to get enough room to maneuver. Carefully remove the old pipe section, being prepared for some residual water spillage, and dispose of the damaged PVC responsibly.
Measuring and Cutting
Accuracy is critical when working with PVC. Take a measuring tape and precisely measure the length of the pipe you are removing, adding about half an inch to that figure for the new PVC connectors. PVC is easy to cut, so mark your cutting line clearly with a marker. A standard hand saw or a PVC cutting tool will work perfectly for this task. Once cut, use a deburring tool or a sharp knife to clean off the small plastic burrs left on the inside and outside of the cut edge. A clean, smooth edge ensures a proper seal and prevents future leaks.
Preparing for a Leak-Free Seal
PVC cement creates a chemical weld, so the surfaces must be clean and dry. Wipe the outside of the pipe end and the inside of the fitting with a clean cloth to remove any dust or residue. Then, apply a layer of purple primer to both the pipe and the fitting. This primer removes the glossy layer and creates a surface for the cement to bond to. After the primer dries quickly, apply a generous layer of PVC cement to the primed surfaces. Remember, you have a very short window—usually about 15 seconds—to slide the pipe into the fitting after applying the cement.
Assembly and Tightening
Quickly and firmly push the pipe into the fitting until it is fully seated. You should feel the pipe bottom out, and you might notice a small amount of excess cement squeeze out. This is normal and indicates a good connection. Immediately wipe away the excess cement to prevent it from damaging your cabinet. Next, reattach the mounting brackets to secure the pipe in place, ensuring it is aligned correctly with the drain. Finally, carefully tighten the slip nuts by hand, followed by a quarter-turn with a wrench, to avoid cracking the fittings.
Testing the Repair
Once everything is back in place, slowly turn the shut-off valves counterclockwise to restore water pressure. Before you open the faucet, use a paper towel or rag to inspect the joints for any signs of immediate dripping. If the area is dry, turn the water on fully and let the faucet run for a minute or two. Check the connections again for leaks. If you observe any water seeping out, you will need to turn the water back off, drain the line, and reapply cement or tighten the nut slightly until the leak stops.
