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How to Connect a Laundry Sink and Washing Machine to the Same Drain?

Everybody wants their laundry sink and washing machine close to each other. Having a laundry right beside your washing machine comes in handy when you need to rinse some clothes from the washer. However, space can be limited, especially when your laundry sink and machine use separate drains.

How to connect a laundry sink and washing machine to the same drain? You can connect a utility sink and laundry machine to one drain using a few materials like a Y-fitting and a standpipe. The method you use to attach the two fixtures varies depending on whether the sink is in place.

How to Connect a Laundry Sink and Washing Machine to the Same Drain

Read on to find out the best method for your scenario, how to make the connection, and the equipment you require.

How to Connect Laundry Sink and Washing Machine to a Shared Drain

You can use a couple of methods to connect a utility sink and laundry machine to one drain. Although the methods differ a little, the equipment used is primarily the same.

Required Tools And Materials

  1. Safety goggles
  2. Solvent glue
  3. Hosepipe
  4. Permanent marker pen
  5. Utility knife
  6. Tape measure
  7. Hacksaw
  8. Wrench
  9. Primer
  10. 90-degree elbow
  11. ½ inch screws
  12. Waste Y-fitting
  13. 2-inch standpipe with a trap
  14. Sandpaper

Method 1: When You Have a Pre-Installed Laundry Sink

This method assumes the sink is already in place, so all you need to do is connect the two fixtures’ drains to a shared drain pipe.

Step 1: Restrict the water supply and disconnect the laundry machine

Use the shutoff valves to stop the water supply to the utility sink and washing machine. These valves are usually located behind the laundry washer. After cutting off the water supply, disconnect the washer from the mains by unplugging it.

Step 2: Measure the waste Y-fitting and drain pipe length

Measure the length of the laundry machine’s drain pipe, beginning at the bottom. Use the marker to mark a straight line on that spot. Measure the Y-fitting’s length.

Step 3: Adjust the drain pipe length

After marking the length on the laundry washer’s drain pipe, use the reciprocating saw to cut at the mark. Use sandpaper, a utility knife, or any suitable tool to remove jagged ends and burrs. Uneven pipe ends may make connecting the drainage lines difficult, so ensure all the edges are smooth.

Step 4: Install the Y-Fitting

Before installing the Y-fitting, dry-fit it with the opening face forward and in alignment with the drain line to see if its measurements are correct. Adjust the Y-fitting’s size until it fits.

Step 5: Install the standpipe

When the glue on the Y-fitting connection dries, align a 90-degree elbow to the Y-fitting’s opening and dry-fit it there. With the elbow in place, connect a standpipe to it.

With the standpipe standing vertically, measure the distance from the bottom to the top and mark the 34-inch mark. Standpipes should be at least 34 inches high to avoid water backup. Take out the pipe and cut it at the marked point. Then, reattach and secure it using the primer and solvent glue.

Secure the standpipe to the wall using a strap. Use the ½-inch screws to keep the strap in place. If there’s too much space between the standpipe and the wall, use a board to fill it.

Step 6: Attach the sink and laundry machine

Assemble the utility sink tailpiece and P-trap and align it to one of the waste Y-fitting’s inlets. Attach it to the fitting, and use the primer and solvent glue to secure it. After you attach the sink’s tailpiece, connect your washing machine’s drainage hose to the remaining Y-fitting inlet and glue it.

Step 7: Testing

Turn the shut-off valves to allow normal water flow to the laundry sink and washer. Replug the washer to the mains and run it with no laundry. Open the laundry sink tap and let the water run as the laundry washer runs. Inspect the plumbing for any water leaks.

Method 2: When There’s No Pre-installed Laundry Sink

If you don’t have a laundry sink installed, use this method to install one and link it and your washing machine to one drain pipe.

Step 1: Shut off the water supply and disconnect the washer

The first thing to do is to disconnect the laundry machine from the mains. Then, stop the water supply from reaching the laundry washer and laundry sink by shutting off the valves.

Step 2: Determine the drain length

Measure the sink’s drain length, starting where it reaches the wall or touches the ground. Next, measure the length of the laundry machine’s drain, beginning at the bottom. Measure the same length as the sink’s drainpipe and mark it.

Step 3: Cut the drain pipe

Use the reciprocating saw to cut the laundry machine at any point above the mark and venting pipe. The T-fitting tube that diverts water from the drain toward the exit must also be adjusted, so cut it accordingly.

Once you’ve cut the pipes, use a utility knife or a suitable tool to remove rough edges. Uneven pipe ends may make connecting the drainage lines difficult, so ensure all the edges are smooth.

Step 4: Use the Y-fitting to connect the laundry sink to the laundry machine drain

The Y-fitting is essential, so you must install it properly. First, attach the PVC Y-fitting to your washing machine’s drain. The upper arm should align with the venting pipe above while the remaining arms connect to different parts.

One of the fitting’s arms should connect to the laundry machine drain’s exit and the other to the laundry sink’s drain. Use the primer and solvent glue to ensure the fitting and drain pipes adhere together firmly. The goal is to ensure that the connections are secured and watertight to avoid any risk of leakages.

Step 5: Find the water supply lines

Next after the drain pipes are the water lines. In this step, look for the fitting from which the hot and cold water pipes that ferry water to your laundry machine branch off. Remove the fitting and adjust the pipe’s length by cutting the ends.

In some instances, the water supply line doesn’t branch into hot and cold. In this case, cut the pipe at the mid-point between the utility sink and the washing machine. Use sandpaper to smooth over the rough edges of the pipes and prevent leaky connections.

Step 6: Add a pipe splitter

After adjusting the water supply length to fit, connect a pipe splitter to divide the water between the sink faucet and washer. Since you must secure the brass splitter’s connection firmly, tighten the nuts with a wrench.

Reconnect the original washing machine pipes to one of the splitter’s openings and use a wrench to ensure a tight connection.

Step 7: Connect the laundry sink to the splitter

Use hoses to link the laundry sink to the cold and hot water lines. For easy differentiation, use different colors for hot and cold. Once you’re sure the length of the hoses is correct, use a nut to hold the connections firmly in place.

After connecting the hosepipes to the supply lines, link them to the laundry sink tap. Use a wrench to tighten the nuts around the tubes and tap.  Glue the connections to ensure water-tight seals.

Step 8: Testing

Once you finish connecting and tightening all the pipes, open the shut-off valves and run the tap to see if there are any leaks. Also, run the laundry machine to see if the drain works as expected. If you discover leaks, seal them and retest until there is no more leaking.

You can consider your quest to the laundry sink and washing machine to a shared drain successful if the water runs through the drainpipes without leaking.


Connecting a laundry sink and washing machine to a shared drain is simple but requires time and labor. Despite being a time and labor-intensive undertaking, it’s worth it in the end because it saves space and reduces water spillage and dirt in your laundry room.

Follow all safety precautions and comply with all plumbing codes if you make this connection a do-it-yourself project.