Why the Door Drain on My Walk-In Tub Is Capped and Should Stay That Way

If your walk-in tub arrived with a short, capped stub where the installation manual shows a secondary door drain, nothing is missing and nothing needs to be connected. Ella's Bubbles eliminated the door drain on its walk-in tubs. Leave the stub capped, do not cut it open, and do not tie it into the main drain line. Your tub drains through the main floor drain and overflow exactly as the rest of the manual describes.

What the Capped Stub Is

Some printed installation manuals still show a small secondary drain line near the door that joins the main tub drain. On current tubs that line has been removed at the factory. What remains is a short length of tubing that has been cut back and sealed with a cap. Installers who follow the drawing in the manual sometimes expect this line to be live, which is why the capped stub raises questions on installation day. It is intentional, and it is not a sign that a part was left off.

Why the Door Drain Was Eliminated

The door drain line relied on a check valve to keep water moving in one direction. In service, those check valves could stick. When that happened, water leaving the tub was pushed back up the line and returned to the door drain instead of going to the house drain. The result was water pushing up around the door area while the tub emptied, which looked like a door leak even though the seal was fine. Removing the door drain and capping the line eliminated that failure point. Ella's tech support confirms that the door drain should stay canceled to prevent leak issues.

What to Do During Installation

1. Leave the cap in place on the short stub. Do not cut, drill, or remove it.
2. Do not connect the stub to the main drain, the overflow, or any house drain line.
3. Connect the main tub drain and overflow as the manual describes. The 4-port T-type drain body under the tub is where your plumber makes the house connection.
4. Skip the door drain step in the manual and continue with the rest of the drain, faucet and electrical work.
5. Fill the tub and run a full drain cycle before the front panel or walls are closed up, and confirm the area around the capped stub stays dry.

Do Not Confuse It with the Breather Lines

Hydro and microbubble tubs also have small loose lines under the rim. Those are hydro breather lines and, on microbubble tubs, a prime port. They belong to the air and hydro system, and they have their own rules, which are explained in Loose Air Lines Under the Rim. The capped door drain stub sits low on the tub near the door and is a drain line, not an air line.

If Water Is Pushing Up Near the Door on an Older Tub

Older tubs that still have a connected door drain can show the original symptom: water squirting up out of the door drain while the tub empties. That is the sticking check valve at work, not a failed door seal. The fix is the same change the factory made. A licensed plumber can disconnect the door drain line from the main drain and cap it. Open a ticket first with your serial number and a photo of the drain area so tech support can confirm what your tub has and advise your plumber. For general drain layout questions such as one P-trap or two, or draining to the floor on a slab, see Common Plumbing Questions and Where Does the Drain Sit for a Slab Installation.

Related Guides

• Plumbing and drain configurations: connecting your walk-in tub to the house drain
• How Fast Does a Walk-In Tub Drain? Dual Drain Technology Explained
• Tub Drains Slowly, Will Not Drain, or Loses Water: What to Check

Common Questions

Still Need Help?

Open a ticket at ellasbubbles.com/support or call (800) 480-6850 and have your model and serial number ready.