How to Plumb a Double Kitchen Sink: A Simple Step-by-Step Guide

Installing or replacing a double kitchen sink can be a rewarding DIY project that helps you save on plumber fees while enhancing your kitchen’s functionality. While plumbing may seem intimidating, the process is actually straightforward with the right tools and knowledge. In this guide, we’ll walk you through the steps to plumb a double kitchen sink, from installation to connecting the drainpipes.

Step 1: Prepare Your Tools and Materials

Before you begin, make sure you have all the necessary tools and materials:

• Adjustable wrenches or pipe wrenches
• Pipe cutter or hacksaw
• PVC pipes and fittings
• P-trap kit
• Plumber’s putty
• Silicone caulk
• Pipe hangers or brackets (if needed)
• Measuring tape
• Bucket (for draining water)

Step 2: Shut Off the Water Supply

Before starting any plumbing work, ensure you turn off the water supply to the sink. You can do this by closing the shutoff valves under the sink. If no shutoff valves are present, you may need to turn off the main water supply for the house.

Step 3: Remove the Old Sink (If Applicable)

If you’re replacing an old sink, the first step is to disconnect and remove it.

1. Disconnect the Drain: Use a pipe wrench to remove the drainpipes. If there's a garbage disposal, disconnect it by unscrewing the mounting hardware and drain pipe.
2. Remove the Sink: Loosen the mounting brackets or screws holding the sink in place. Carefully lift the sink out of the countertop cutout once everything is disconnected.

Step 4: Install the New Sink

Now that the countertop is clear, it’s time to install your new double kitchen sink.

1. Position the Sink: Set the sink into the countertop cutout to check the fit. Apply a bead of silicone caulk around the edge of the cutout to create a waterproof seal.
2. Secure the Sink: Once positioned, use mounting hardware to secure the sink to the countertop. Tighten the brackets or screws until the sink is firmly in place.

Step 5: Connect the Drain Pipes

Now for the crucial part: connecting the drain system. Double sinks typically have two separate drain lines that merge into one larger drainpipe.

1. Install the Waste T: Attach a "T" fitting to connect the two drain lines from each basin. This allows both drains to lead into a single outlet, which then flows into the P-trap.
2. Connect the P-trap: The P-trap prevents sewer gases from entering your kitchen. Attach it to the "T" fitting and then connect it to the drainpipe that leads to the main waste line.
3. Seal the Joints: Wrap Teflon tape or apply pipe thread sealant to all threaded connections to avoid leaks. Tighten the connections securely with a pipe wrench.
4. Install the Drain Line: Attach the drainpipe from the P-trap to the main waste line. Ensure that the pipes are properly sloped to encourage water drainage.

Step 6: Install the Faucet

Once the drain system is in place, it’s time to install the faucet.

1. Position the Faucet: Place the faucet in the pre-drilled hole on the sink. Apply plumber’s putty around the base of the faucet to create a tight seal.
2. Secure the Faucet: Under the sink, tighten the mounting nuts that hold the faucet in place.
3. Connect the Water Supply Lines: Attach the flexible water supply lines to the faucet and connect them to the hot and cold water supply valves. Tighten the connections with a wrench, but don’t overtighten.

Step 7: Check for Leaks

With everything in place, it’s time to check for leaks.

1. Turn On the Water: Slowly open the water supply valves and check the faucet, drain connections, and P-trap for any leaks.
2. Test the Drainage: Run water down both sides of the sink to ensure it drains properly without any blockages or slow drainage.

Step 8: Final Adjustments and Sealing

Once you’ve confirmed that everything is functioning properly, it’s time to finish up.

1. Seal the Edges: Apply a final bead of silicone caulk around the edge of the sink to prevent any water from seeping underneath.
2. Clean Up: Wipe away any excess caulk or plumber’s putty, and ensure the area is tidy.

Conclusion

Plumbing a double kitchen sink is a manageable DIY project that can save you money and give your kitchen a functional upgrade. By following these steps, you can ensure that your double sink is installed and plumbed correctly, offering both convenience and peace of mind. Remember, a little preventative maintenance, like checking for leaks and using drain strainers, can keep your plumbing system running smoothly for years to come.