Pennsylvania’s residential code text asks a dishwasher’s drain line to rise to the underside of the counter and be held there. One maker calls that a high loop. Whether the drain also needs a dishwasher air gap is a separate check, and you make it with your township’s code office and the instructions that come with the model you pick.
A local rule can ask for more than the code text names. So can the instructions.
That answer feeds the plan your designer and your plumber work from. It’s easier to settle while the sink, the counter and the dishwasher spot are still on paper. Once they’re ordered, you’re working around them.
What Does Pennsylvania’s Code Say About a Dishwasher Drain?
The code text says the dishwasher’s discharge pipe or tubing shall rise to the underside of the counter. It must be “fastened or otherwise held in that position” before it connects. From there it goes to the head of the food-waste disposer or to a wye fitting in the sink tailpiece.
The wording sits in the plumbing-fixtures chapter, at Section P2717. Pennsylvania’s residential code text for dishwashers is published on a code-reference site, and the same section covers the water side too. It says a dishwasher’s water supply shall be protected against backflow by an air gap installed within the machine or by a backflow preventer.
That built-in air gap guards the supply side. It’s a different thing from the drain-side question. The drain rule names no air gap fitting. It also names where the line ends up, at a disposer or at a wye fitting in the sink tailpiece, which is worth knowing if a disposer is in the plan. And a code-reference page isn’t your township’s ruling.
The code office applies the rules at your address, so your answer comes from that office.
Do You Need a Dishwasher Air Gap?
Pennsylvania’s code text asks for the rise and the fastening. It names no dishwasher air gap on the drain side. A local rule can ask for one, and so can the dishwasher’s own instructions. So the answer comes from your township’s code office and the model’s instructions, not from a rule of thumb.
One maker puts it in its own words. Its support page says a dishwasher’s drain hose should connect to the house drain either directly or through an air gap. It also says that without a high drain loop or an air gap, dirty water from the sink can flow into the dishwasher. On that page, the loop and the air gap are both ways to guard the same drain.
The same maker describes that loop by height. According to one dishwasher maker’s support page on the drain loop, a high drain loop is created when the hose is installed with a loop a minimum of 32 inches above the floor, and it’s made by attaching the drain hose to the underside of the countertop. That height is one maker’s figure, not a rule.
Read together, the code text and that page both send the hose high before it drops. But other makers give other heights. And the page doesn’t describe an air gap fitting or say where one goes. So the instructions that come with the model you choose are the ones to follow, and your plumber can confirm the drain. Don’t plan it from a picture.
What Should You Settle Before the Sink and Counter Are Set?
Put these answers on the plan. Where the sink and the dishwasher will sit. Whether the drain connects to a disposer or to a wye fitting in the sink tailpiece, since the code text names both. Which dishwasher model is planned, and what its instructions say. And who will check the rule with the township’s code office.
These are questions for your designer and your plumber. They’re easier to answer while the cabinets and the counter are still drawings. Shifting a sink on paper takes a conversation. Shifting one after the order is placed is a different story. The model matters as much as the spot. Its own instructions are the ones that govern it, so pin the model down early.
If the sink moves to an island, the pipes follow it. Lang’s post on what a kitchen island sink asks of the dishwasher and the pipes says supply and drain have to be run out to the island, and the drain still has to be vented. Your designer can answer the layout half, and your plumber answers the rest.
Who Checks the Rule at Your Address?
The building code office of your township or borough applies the rules at your address. The dishwasher’s installation instructions add their own requirements on top of that. Your plumber confirms the drain connection on the job. Those are the places to get the answer, and your designer can put it on the plan.
Lang’s post on which kitchen changes call for a permit in Bucks County points at the same starting line. A moved sink or dishwasher can touch water supply and drain, so the place to begin is the building code office of your township or borough.
Raise the drain question at your design consultation. Ask who will confirm it, and ask when. Then get the answer onto the plan in writing. An answer on the plan is one less surprise later.
What Should You Bring to a Design Consultation?
Bring the model number of the dishwasher you own or the one you’re considering. Bring photos of the sink wall. Bring a note of where you’d like the sink and the dishwasher to sit. And bring any notes your plumber has already given you about the drain.
With that in hand, your designer can mark the sink and the dishwasher on the plan. A jobsite visit can check those marks against the real room. Rooms hold surprises. Paper doesn’t.
At Lang’s, every home and every family is different, so each kitchen is a one-of-a-kind design made for that client. In kitchen remodeling with Lang’s certified designers, your designer works with you to find a layout that fits how you plan to use the room, helps you choose materials and walks you through every step of the remodeling process.
Frequently Asked Questions About Dishwasher Drains
Is a dishwasher air gap required in Pennsylvania?
Pennsylvania’s code text asks the dishwasher’s drain to rise to the underside of the counter and be fastened or held there. It names no air gap on the drain side. A township’s rule or the model’s installation instructions can say something different. So ask your township’s code office what applies at your address, and follow the instructions that come with the dishwasher you choose.
What is a high loop on a dishwasher?
One maker’s support page describes it as a loop in the drain hose a minimum of 32 inches above the floor, made by attaching the hose to the underside of the countertop. The code text asks for a similar rise to the underside of the counter, where the line is fastened or otherwise held. Other makers give other heights, so follow the instructions for your model.
Can a dishwasher drain into a garbage disposal?
The code text lets the discharge connect to the head of the food-waste disposer or to a wye fitting in the sink tailpiece. Either way, it rises to the underside of the counter and is held there first. Which one fits your sink setup is a question for your plumber, and it’s worth asking before the sink is chosen.
Is there an air gap inside the dishwasher?
The code text says a dishwasher’s water supply shall be protected against backflow by an air gap installed within the machine or by a backflow preventer. That’s the supply side, and it’s a different matter from the drain. Check the installation instructions for the model you’re considering to see how its supply protection is handled.
Who can help me plan the dishwasher spot?
Lang’s design team. Design consultations are available in the showroom and online by appointment. Lang’s 12-step process includes a jobsite in-home analysis, and a final plan stage where the design team finalizes all dimensions, floor plans and mechanical specifications. Bring the dishwasher model number and your plumber’s notes, and the drain question can go on the plan with everything else.
Bring Your Dishwasher Plan to a Design Consultation
In Lang’s 12-step remodeling process, designers visit the jobsite for a complete in-home analysis before the design team finalizes all dimensions, floor plans and mechanical specifications.
The drain question is easiest to settle while the plan is still on paper. So it’s worth bringing the dishwasher model and the code question to the first meeting.
Lang’s 12-step remodeling process lays out the steps from the first appointment through final plans.
Still weighing a dishwasher air gap against a loop? Bring the model number and talk with Lang’s design team before the counter is ordered. Lang’s design showroom is in Newtown.
