It is possible to upgrade a kitchen or bathroom for less money than it costs to install new flooring and appliances by installing a new sink and faucet coupled with a new countertop and sink faucet. Installing a new sink and faucet is not that difficult these days, thanks to fittings that screw or glue together, necessitating no solder or torches in many cases. So, how do you install sink plumbing?
The plumbing for the bathroom sink is installed in two stages. The rough-in is when all the water, drain, and vent pipes are installed in the walls and left stubbing out at the sink placement. The sink and faucet connect to the stub-outs in the second, or finishing, phase. The rough-in step necessitates excellent plumbing knowledge. However, finishing should be trouble-free if done correctly.
While it is uncommon for a kitchen sink’s drain assembly to fail and require repair when a sink is changed as part of a kitchen remodeling or update project, part of the procedure frequently includes installing a new sink plumbing assembly for the new sink.
How To Install Sink Plumbing
Kitchen Sink Plumbing
In the old days, putting up a new sink and faucet was difficult, and connecting the sink’s drain—the sections that connect the sink’s tailpiece to the waste line—was the most difficult. Always begin at the tailpiece of the sink and work your way down. This is when a swivel P-trap with a trap adaptor proves beneficial. It can adjust up and down on two distinct axes and swing side to side.
Installation Procedures
Measure and Mark the Sink’s Layout
- Mark the rear border of the counter to position the sink within its cabinet.
- Align the sink template with the countermark if it has one. Its posterior border should be 1 ½ inches from and parallel to the counter.
- Trace around it and move on to the next step. Use 2-inch tape to indicate the sink placement if no template is available.
- On the rear lip of the sink, mark the middle.
- Place the sink on the counter upside down. Align the sink mark with the one on the counter.
- Adjust the sink’s back edge to leave 1 ½ inches between it and the backsplash. Check that the sink is parallel to the counter’s edge.
- Remove the sink after tracing it around it.
- Subtract 1/8 inch from the width of the sink lip and indicate the amount inside the sink shape.
- Connect all of the markings with a straightedge to create the cutout lines.
Draw the Cut Lines on the Counter
- After connecting the markings with a straightedge, the sink’s hole on the counter will be rectangular.
- Hand off the corners to approximate the radius of the sink’s corner.
- Next, drill a hole within the radius at each corner of the cutout lines with a slightly broader spade than the jigsaw blade (½ inch bit is generally sufficient).
Using a Jigsaw, Cut a Sink Opening
- Insert a jigsaw blade into the front hole and cut along the cut line to the back hole. Then repeat on the other side.
- Across the sink area, place a piece of wood a few inches longer than the cutout. Screw through the debris and into the waste cut out to keep it from dropping or binding the saw blade.
- Cut following the cut lines on the front and rear. Take out the cutout portion.
- Check the fit of the sink in the countertop; if required, cut the hole using a jigsaw.
Set Up a Kitchen Faucet
- Place the sink on an upside-down sawhorse or counter.
- Feed the supply tubing tailpiece of the faucet through the gasket that seals the tap on the sink and then up the sinkhole.
- Screw the washers and mounting nuts underside of the sink deck.
- Before tightening the mounting nuts, ensure the faucet can swing in an entire arc over the sink.
Connect the Strainer to the Plumber’s Putty
- Pack a thick roll of plumber’s putty beneath the strainer’s lip and push it up through the sink’s drain while the sink is still upside down.
- Slip the filter’s gasket, washer, and housing onto the strainer and against the underside of the sink. Apply pipe joint compound to the exposed threads.
- Hand-thread and locknut onto the filter, then tighten it with pliers while holding it in place.
- Insert the gasket into the sink-drain tailpiece and secure it with the slip nut to the filter. Tighten the nut with your hand while holding the filter.
Install the Sink and Connect the Water Supply
- Pull the tape away from the hole, toward the center.
- Squeeze a bead of silicone caulk along the underside of the sink’s lip while the sink is still upside down.
- Place the sink upright into the countertop hole.
- Ensure the sink’s front is parallel to the countertop’s front border. If necessary, make the appropriate changes.
- Connect your faucet to the shut-off valves using acorn-head supply tubes or braided stainless steel hoses.
- Attach the sprayer hose to the threaded tailpiece of the faucet.
Connect the Drain Pipes
- Attach the trap adapter to the sink-drain tailpiece.
- To connect the trap adapter to the trap and the drain elbow to the waste line, cut and dry-fit lengths of PVC pipe. Swivel or move the trap on the tailpiece to fine-tune the sizes and alignment of the pipes. Then, disassemble the drain components.
- With a utility knife, remove the cut ends. Apply PVC primer. Allow drying.
- Swab PVC cement on both ends of the joint. Put the pieces together right away. Hold the position for 30 seconds.
- Reassemble and tighten any threaded connections by hand.
Connect the Dishwasher Drain and Clean Up
- Connect the dishwasher drain line to the tailpiece’s waste nib. Tighten the hose clamp using a screwdriver.
- Remove any extra putty from the filter’s lip.
- Remove the aerator from the faucet and turn on the water. Examine all connections along the supply and drain lines for leakage. In the event of a leak, slowly tighten the one-eighth nuts turn at a time until the flow stops.
- Check that the front edge of the sink is parallel to the counter’s edge. Fill the sink with water to weigh it down and keep it tight while the caulk cures.
Bathroom Sink Plumbing
The drain, supply, and vent pipes for the sink are connected to the pipes already serving your bathroom, and the rough-in complexity relies on the system’s overall arrangement. Sinks do not use much water, so you should be able to branch the ½ inch supply lines from the shower or tub. Similarly, you can typically connect the 2-inch drain line to an existing one.
Furthermore, it is critical to remember to vent the sink, or it won’t drain correctly. The 1 ½ or 2-inch vent must rise from the drain within 5 feet of the sink trap. It is either tied into an existing duct or continues into the roof.
Pipe Installation
It is critical to locate the supply and drain stub-outs. The drain should be centered between the supply stub-outs and aligned with the sink drain. The pipes must be routed through the wall. The water must turn off when the tees are soldered onto the lines from which the supply is drawn.
Furthermore, the drain must have a minimum slope of ¼ inch per foot toward the sewer, and the vent must have a minimum pitch of ¼ inch per foot upward toward its tie-in point. Allow the stub-outs to protrude a few inches from the wall before capping them until the sink is ready to be installed.
Getting the Stub-Outs Ready
Install shutdown valves on the supply stub-outs before connecting the sink. After removing the caps with a pipe cutter, you may sell slip-joint valves to the pipes or use a wrench to tighten compression valves. You might also glue the valves if you used CPVC plastic pipes instead of copper. If you do not wish to glue the P-trap to the waste pipe, you may glue on a P-trap adaptor, which converts the line to a threaded compression connection that will accept a 1 ½ inch P-trap extension pipe.
Installing the Sink
It is always better to preinstall the faucet and drain it onto a sink before installing it so that you do not have to perform these tasks while lying on your back. The tailpiece is the pipe that runs down from the drain and should stop at the same level as the top of the drain. Therefore, the trap may easily attach.
The supply hoses attach to the cutoff valves and faucet inlets and are tightened with adjustable pliers. They must have the correct size connections to fit, so double-check before purchasing the hoses. After attaching the pop-up stopper, the sink should be ready to use.
Finishing a Bathroom Toilet Sink with Existing Rough Plumbing
The most challenging component of installing a bathroom sink is installing the rough plumbing, so you are in luck if it is already there. It should have a drain and two water stub-outs. The sink installation is more straightforward if the water stub-outs have shut-off valves.
However, if they are not, you may easily add them. If you can center the sink over the drain stub-out, connecting the sink P-trap and making it leakproof will be easy. However, if not, you may need to install angle fittings to the sink drain pipes.
Finishing Procedures
If they are not already there, install shut-off valves on the hot and cold water pipes. Look for valves that control the lines you’re working on so you can turn off the water. Turn off the house’s primary water valve if you can’t discover any specialized valves.
- Using a pipe cutter, remove the soldered caps from the pipes. Allow roughly 1 inch of pipe to protrude from the wall.
- Connect a valve to a compression fitting by sliding the compression nut onto the pipe and fitting the brass collar included with the valve onto the pipe’s end. Place the valve on the line and manually tighten the nut.
- Tighten the valve by gripping it with adjustable pliers and turning the nut clockwise relative to the valve with a wrench.
- Suppose the drain stub-out does not already have an ABS P-trap adapter. Glue one on with ABS cement. The adapter decreases the drain aperture from 2 to 1 ½ inches and includes a compression fitting for attaching the trap outlet.
- Attach the drain and faucet to the sink before placing it in the vanity or attaching it to the wall. Faucets come in various styles, but most connect to the sink through a retaining nut that you tighten using adjustable pliers.
- Screw the tailpiece or drain extension onto the filter and liberally apply the plumber’s putty to the bottom of the strainer lip. Insert the filter into the hole and secure it with the retaining nut beneath the sink. Using adjustable pliers, tighten the nut.
- Connect the faucet to the water supply using flexible supply hoses. These are not included with the faucet, so be sure they’re long enough and that the connections suit your faucet and shut-off valves when you buy them. Tighten the hoses to the shut-off valves and faucet stems using adjustable pliers.
- If the drain tailpiece extends below the hole, cut it using a hacksaw. It should ideally be at or slightly above the same level. If it’s longer than 2 inches, add an extension, a piece of 1 ½ inch PVC tubing with a compression fitting.
- Hand-tighten the P-trap intake to the tailpiece or extension. Swivel the trap to line the outflow with the drain stub-out, then measure the distance between the two. Cut a 1 ½ inch PVC pipe 2 inches longer than the calculated distance and place the ends into the trap outflow and drain inlet. Tighten the compression nuts by hand at both sites of connection.
- Turn on the water to the shut-off valves, then the valves. Allow the air to escape by opening the faucet and filling the sink. Allow the water to drain from the sink, and check the drain connections for leaks. Using adjustable pliers, tighten any leaky connections.
When To Call the Pros
It is often advisable to hire a professional plumber to install your sink. If the plumbing in your new sink does not match the plumbing in your old sink, or if you want to change the size of a sink, this is another reason to bring in professionals.
Do you require professional assistance? Do you live in Scottsdale, AZ, and the East Valley cities of Mesa, Chandler, Tempe, or Gilbert? Please contact us as soon as possible so we can install your sink and handle your other plumbing needs.
