Bathroom vanities

Bathroom vanity drawers that fit around the sink plumbing

By Dale McCoy, head of production · Updated October 2026

A vanity hides its best storage behind two doors and a false front, because the P trap and the pop up drain sit right where a drawer would go. A U shaped drawer box with a plumbing notch fixes that. This page is for anyone planning a vanity, from a 24 in powder room cabinet to a 72 in double bowl, and for the cabinet shop building it.

Ready to build it? Build your U shaped sink drawer: the configurator prices every choice live and draws your box in 3D, notch included, before you order.

A worked example: a 30 in vanity with one deep drawer

A frameless 30 in vanity, 21 in deep with 20 in inside, an undermount bowl with the drain a little right of center, Blum TANDEM plus BLUMOTION 563 runners and 5/8 in sides. The stops sit 12 in above the cabinet floor over the right leg.

1. Width. The opening is 28 1/2 in, minus 13/32 is 28 3/32 in.
2. Depth. 20 in inside clears the 18 29/32 in an 18 in TANDEM needs, per Blum, so the box is 18 in deep.
3. Height. 12 in to the stops, minus 1 in of room, minus 9/16 in under the box, allows up to 10 7/16 in. An 8 in box leaves 3 7/16 in under the stops.
4. Distance to notch center. The trap and the pop up strap run from 13 1/2 to 18 1/2 in off the left cabinet side, so the plumbing center is 16 in. Subtract the 13/64 in of slide clearance on the left and round to the nearest 1/32 in: 15 13/16 in, typed as 15.8125.
5. Notch width. 18 1/2 minus 13 1/2 is 5 in, plus 1 in each side: 7 in.
6. Distance from the front to the notch. The front of the trap is 9 in behind the front edge of the cabinet sides, minus 1 in: 8 in, so the notch reaches 10 in into the 18 in box.
7. Rules. Left leg 15 13/16 minus 3 1/2, or 12 5/16 in; right leg 28 3/32 minus 15 13/16 minus 3 1/2, or 8 25/32 in. Both legs, the 8 in front section and the 10 in notch depth clear the 3 in minimum, so the preview shows no red warning.

On side mount slides the box is 27 1/2 in and the distance to notch center is 16 minus 1/2, or 15 1/2 in. The left and right edge method is in how to measure plumbing for a U shaped drawer.

Humidity, finish and the bottom

A bathroom is damp, so order the box finished and plan on wiping up spills. Baltic Birch ships finished and handles a damp cabinet better than the particleboard most vanities are built from; Hard Maple (Select Grade) ships finished or unfinished, so choose Finished. A 1/4 in white, black or maple melamine bottom wipes clean. Fix a leak the day you find it; the wood box carries a lifetime warranty. Compare Baltic Birch and Hard Maple boxes, and the bottoms on drawer bottom options.

Vessel sinks, wall hung vanities and double bowls

• Vessel sinks. The bowl sits on the counter, so the trap hangs just under it, leaving the most height of any vanity for a deep drawer or a stack.
• Wall hung vanities. Often 18 to 20 in deep, which means a 15 in runner. The drain and stops come out of the wall behind the cabinet, inside the open back of the notch; some floating vanities use a compact trap tucked close to the wall, so measure the frontmost point of whatever trap you have.
• Double bowl vanities. Each sink section, 24 to 36 in wide in a 60 or 72 in vanity and about 24 in in a 48 in double bowl, gets its own U shaped drawer with its own three numbers; a 24 in section takes a box about 22 3/32 in wide on Blum runners with legs of about 7 1/2 in beside a 7 in notch. The drawer bank between takes plain custom drawer boxes.

Bathroom vanity drawer questions

Can a bathroom vanity have drawers under the sink?

Yes. A U shaped drawer box has one full height notch cut out of the back, open at the rear, so the tailpiece, the pop up rod and the P trap sit inside it and the drawer slides out around them. The doors come off and a drawer front goes on.

How tall can a drawer under a bathroom sink be?

Tall enough to stay about 1 in below the lowest stop or pipe over a leg, our suggestion, after the 9/16 in a Blum TANDEM 563 runner needs under the box, per Blum. Stops 12 in above the cabinet floor allow a box up to 10 7/16 in tall; the trap in the notch never limits height.

What about the pop up drain rod?

It sits behind the tailpiece, toward the wall, inside the notch, which is open at the back. Include the pivot rod and its strap when you measure the left and right edges of the plumbing, because the strap hangs a little to one side; with a 1 1/4 in trap the group usually fits a 6 to 7 in notch.

Can I have two drawers under a bathroom sink?

Yes, when the cabinet is tall enough: a 6 to 8 in lower drawer notched around the trap and a 3 to 4 in upper drawer with a wider notch around the tailpiece and the pivot rod. Each box gets its own three numbers, ordered as two boxes.

Does a double sink vanity need two U shaped drawers?

One per sink section, each with its own three numbers, because the drains are far apart and our boxes go up to 35 31/32 in wide. A 48 in double bowl takes two boxes of about 22 3/32 in on Blum runners; the drawer bank between takes plain custom boxes.

Will a U shaped drawer work in a wall mounted vanity?

Yes. A floating vanity is usually 18 to 20 in deep, so the box runs on 15 in runners, and the drain and stops come out of the wall behind it, inside the open back of the notch. Measure the frontmost point of the trap, since some use a compact trap tucked close to the wall.

Is a vanity notch narrower than a kitchen sink notch?

Usually. Bathroom traps are 1 1/4 in pipe where kitchen traps are 1 1/2 in, and there is no disposal, so a vanity notch is typically 6 to 8 in wide against 8 to 12 in in a kitchen. Those are typical ranges, so measure your own trap and strap.