Double Sink Plumbing: A Step-by-Step Installation Guide for Intermediate DIYers
Understanding the Plumbing Configuration
Double-basin sinks require a slightly different plumbing setup compared to single-basin sinks. Instead of a direct connection from the sink tailpiece to the P-trap drain, each sink in a double-basin setup connects to a sanitary tee, which then joins the P-trap drain. This configuration allows waste from both sinks to flow into a single drainage line.
Materials and Tools You’ll Need
- Double sink
- Compression nuts and washers
- Plumber’s putty or silicone caulk
- Sanitary tee
- PVC pipe
- Teflon tape or silicone sealant
- Kitchen drain trap kit
- Sink drain and strainer assembly
- Faucet
- Tape measure
- Hacksaw
- PVC pipe cutter
- Channel locks
- Marker
- Caulking gun
- Screwdriver
Step-by-Step Installation Instructions
1. Install Sink Strainers
Apply plumber’s putty or silicone caulk to the underside of the basket strainer and insert it into the drain hole in the sink. Tighten the strainer nut from below to secure it. Repeat for the second sink.
2. Put the Sink in Place
Apply plumber’s putty or caulk to the countertop around the sink hole. For drop-in sinks, the sink edges should rest on top of the counter, while undermount sinks need to be secured with heavy-duty clips and adhesive.
3. Measure the Drain Outlet Height
Measure the height of the drain outlet pipe with a tape measure. It should be high enough for the P-trap but low enough for the drain tailpieces and sanitary tee to connect. If adjustment is needed, contact a plumber.
4. Connect the Drain Tailpieces
Cut the drain tailpieces to the desired length and connect them to the basket strainers with slip-on compression nuts. Tighten the nuts using channel locks.
5. Add in the Sanitary Tee
Install the sanitary tee either in line with one sink or in the middle of both sinks. Connect the drain tailpieces to the sanitary tee using compression nuts.
6. Install the Drain Trap
Connect the sanitary tee to the U-shaped trap, then the U-shaped trap to the J-shaped trap. The tail-end of the J-shaped trap connects to the drain outlet pipe.
7. Mount the Faucet
Thread the faucet mounting bracket and water lines through the countertop and secure the faucet with nuts.
8. Connect the Hot and Cold Water Lines
Connect the faucet water lines to the corresponding hot and cold water pipes under the sink.
9. Check for Leaks
Turn on the isolation valves and check for leaks. Open the faucet to release any air and inspect all components thoroughly, including the drain lines, water lines, P-trap, sanitary tee, and sink edges.
Tips for Troubleshooting
- If you encounter leaks after installation, check the tightness of all compression nuts and connections.
- If the drain is slow or clogged, remove the P-trap and check for debris.
- For major leaks or complex issues, do not hesitate to contact a professional plumber.