Short definition
A continuous waste tee is the slip-joint fitting that joins the two tailpieces of a double-bowl sink into a single drain run feeding one trap. It comes in two configurations — end-outlet (trap drops below one bowl) and center-outlet (trap drops between the bowls) — and is sold as part of a “tubular waste kit” with the tailpieces and P-trap.
What it is
When you have a two-bowl kitchen sink, both bowls drain to a single P-trap, not two. The continuous waste tee is the fitting that combines them. Each bowl has its own basket strainer and tailpiece; the tailpieces drop down and meet at the tee, which then sends the combined flow to the trap.
Two layouts are common. Center-outlet waste kits put the trap directly between the two bowls — the most common factory configuration on a standard double-bowl sink with no disposer. End-outlet waste kits route both bowls’ flow to one end and put the trap below that bowl — used when the other bowl houses a disposer (the disposer’s discharge needs a clear path to the trap) or when the under-sink layout demands an off-center trap.
Modern kits are 1½-inch polypropylene tubular thin-wall with slip-joint connections. Chrome-brass exists in restoration work but is rare in new installs.
Why it matters to a homeowner
The continuous waste tee shows up on a parts-counter shopping list as a “double-bowl waste kit” or “1½-inch tubular waste kit.” Buying the wrong configuration is the most common mistake during a DIY sink install. If you’re adding a disposer to one side of a double bowl, you almost always need to switch from a center-outlet to an end-outlet kit so the trap isn’t fighting the disposer’s discharge.
The tee is also the chronic clog point in a double-bowl sink. Food scraps from one bowl can bridge across the tee and back-pressure into the other, leaving you with a sink full of standing water on the side you weren’t even using. When that becomes a recurring problem, swapping a center-outlet kit for an end-outlet kit usually fixes it.
Common failure modes
- Slip-joint washer leak — slow drip at the tee inlets or outlet; tighten gently by hand, then replace the beveled washer if it persists.
- Center-outlet diverter clog — food bridges between bowls; pull the tee, rinse, and consider switching to end-outlet if the problem repeats.
- Slope error — if the horizontal run from one bowl to the tee is flat or backwards, that bowl drains slowly and water sits in the tee.
- Misaligned tailpiece — forcing a tailpiece into the tee at an angle crushes the washer and leaks.
- Cracked plastic from over-tightening — slip nuts only need hand-tight plus a quarter turn; channel-lock pliers crack PP fittings fast.
Common variants and what a continuous waste tee is not
- End-outlet vs. center-outlet. End-outlet places the trap below one bowl. Center-outlet places it between them. The two kits are not interchangeable — pick before you buy.
- Continuous waste tee vs. general-purpose waste tee. Any drain tee can be called a “waste tee” in trade slang. The continuous waste tee specifically refers to the double-bowl-sink fitting.
- Disposer-side tee. A specialty version with one slip inlet sized for the disposer discharge tube and one for a plain tailpiece. The disposer outlet usually sits a little higher than a plain tailpiece, so this tee accommodates the offset.