How to Vent a Kitchen Sink under a Window

Why do most houses have the kitchen sink directly under a window? To break the monotony of peeling potatoes and washing dishes because they are not the most exciting chores of course.

You want to have your sink in that position so you can distract yourself with whatever is going on outside.

Your plumber will install your drainpipes to run downward for purposes of directing wastewater to the main sewer line and vent pipes upward to let out unpleasant gases into the air.

That said; the kitchen window position hinders vertical venting and that is why it is important to have an alternative venting route.

The wiring and plumbing procedure can be difficult…

Nevertheless, we are here to make things a little bit easier for you. Do not fret if you have no prior experience because if you follow the following steps, venting your kitchen sink will be a walk in the park.


Without correct venting, your sink is likely to drain slowly hence causing water locks in your drainpipes.

What You Need

  • Tape measure
  • PVC sanitary T-fitting, 2-by-2-by-1.5 inch
  • PVC primer
  • Drill
  • PVC adhesive
  • Chalk line
  • 1 1/2-inch diameter PVC pipe
  • Pipe saw
  • 2-inch diameter PVC pipe
  • Hole bit, 1 3/4 inch
  • PVC T-fitting
  • PVC elbow fittings

Vent a Kitchen Sink under a Window

With the following step-by-step process, you will be able to prevent your sink from clogging.

Step 1

Take the 2 by 2 by 1.5 inch T-fitting and attach it to your flat sink drainpipe so that it connects with the waste 2-inch drainpipe from the sink. Just as the name suggests, this fitting is shaped like at T and is designed to connect three openings.

Anyway, you will find this connection in the wall that is right behind the sink. The T-fitting openings measure 1.5 inches (this should face upward) and 2-inch openings that should face down.

Remember to use PVC adhesive and primer whenever you install PVC fittings to ensure that they hold up well.

Step 2

Choose the alignment of the vent pipe. Ideally, the sanitary T-fitting’s top and the vent pipe must spread out upward a little, turn and then horizontally extend through the wall studs to the point where it can vertically ascend again.

Step 3

Using a pipe saw, cut a small upright piece of 1 1/2-inch PVC pipe and link it to the opening that is on top of the sanitary T-fitting. Use PVC primer and adhesive to do this.

The length of the cut piece will depend on the slope and distance of the flat pipe so you might want to measure that using a tape measure.

However, it is usually about 2 inches.

Step 4

Take your chalk and draw a line on the wall studs sides to signify the horizontal vent pipe slope and length.

Using your drill make a 1 5/8 -inch hole on each stud between the point where the vent rises and the elbow. On the line, there will be a few holes and you need to center all of them.

Step 5

On the 1 ½-diameter inch pipe, cut a piece that reaches from the elbow to where the vent escalates. Insert the piece through the holes you had previously centered and stick it to the elbow.

Fasten another elbow to the other side of the channel with its opening facing upward.

Step 6

Connect an upright PVC vent pipe vertically until it reaches the attic. This is what will release all those unwanted gases in your kitchen. However, you may have to drill through your ceiling for the pipe to pass through.

Step 7

Fasten another PVC joint to the top of the outlet pipe in the attic, and horizontally run the pipe with the accurate slope. This should connect with your house’s soil stack and main vent, which should have a diameter of 3-4 inches.

Step 8

Join the outlet pipe to the stack. Do this using a PVC T-fitting that can accommodate the 1 ½-vent pipe and the stack.

You have now successfully vented your kitchen sink.

Why the Kitchen Sink is Generally Placed Under a Window

There is no rule stating that kitchen sinks have to be positioned under a window. However, you will find that this is the case in most homes.

Why do you think that is? Here are several reasons why most people prefer to have it that way. 

  1. It facilitates resourceful use of cabinet space. It is best to have your kitchen window over a sink otherwise; you would have cabinets hindering whatever you need to do in your sink.
  2. Whether your kitchen overlooks the sea where you can have a beautiful view or your backyard where you can keep an eye on your kids as they play, you get a chance to connect with the outside world.
  3. Kitchens have several visual central points and one of them is the sink. This is because it is a key work area in the room.
  4. A window above your sink adorns the work area to make it more aesthetically appealing.
  5. It is important for a kitchen to have ample natural lightingYou also do not want to wash your dishes or vegetables in a dimly lit room.​ It is for this reason that most sinks are placed under windows.
  6. Some people love to connect with nature even when inside their homes. Perhaps you want to experience the fresh smell of your backyard garden or you simply want to release smells from your kitchen.

A window above the sink will help you achieve all that.


We do not know about you, but a kitchen without a window seems incomplete and so is one without a sink. Of course, venting plays a huge role in this.

Without proper venting, your pipes are likely to clog and unpleasant gases will enter your kitchen. Surely, you do not want that, do you?

Hiring a plumber to do the job is an option but it may cost you an arm and a leg so you may want to do it yourself.

We believe you are adequately equipped after reading this article so good luck!

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