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Common Plumbing Questions: One P-Trap or Two, Y Versus T, Center Drains, Drain to the Floor, Supply Threads and No Drain Pump

Updated September 2026

▶Glossary12
  1. Is It Okay to Use a Single P-Trap for Both Drains?
  2. Should I Use a Y or a T Fitting?
  3. Can I Have a Center Drain?
  4. Do the Drains Go to the Floor or the Wall?
  5. Where Does Ella's Plumbing End and My Plumber's Begin?
  6. Can the Tub Be Removed Later Without Cutting Pipe?
  7. Are the Supply Connections Pipe Thread or Hose Thread?
  8. Do You Include Shut-Off Valves?
  9. Is There a Drain Pump?
  10. Does the LayDown Have Dual Drains?
  11. Related Guides
  12. Common Questions

These are the plumbing questions installers and owners ask most often, answered in a sentence or two each, with a link to the article that goes deeper. The short version: Ella tubs use 2 inch gravity drains that go to the floor, one P-trap serving both drains is common, a Y fitting drains faster than a T, the supply connections are 3/4 inch female pipe thread with two braided lines included and no shut-off valves, and there is no drain pump anywhere in the system.

Is It Okay to Use a Single P-Trap for Both Drains?

Yes. The two 2 inch drains each feed a T-type body with two ports, and the most common build ties two of the four ports together into one house connection with one P-trap. Connecting all four ports drains fastest, and connecting only one still works. Caps for the unused ports ship with the tub. A P-trap on each drain, as shown in the video below, is equally acceptable; your plumber places the traps to local code. Deeper: plumbing and drain configurations.

Should I Use a Y or a T Fitting?

Either connects, but a Y is better. Every change of direction slows the water, and a Y sends the flow on with fewer turns, so the tub empties faster. On a Transfer60, all four ports can be connected to a 2 inch or 3 inch main for the most drain capacity. Deeper: dual drain technology and drain speed.

Can I Have a Center Drain?

Only on certain two-seat tubs, such as the Tub4Two and Big4Two, which drain in the middle between the facing seats. The Front Entry, with its door at the end of the tub, has its own single 2 inch two-port drain; check its drawing for the exact location. Every other single-seat tub drains at the left or right end, and the door with the seat sits at the opposite end from the drain, so choose the side based on where your house drain is, and confirm the plan with your installer before ordering. Deeper: choosing the left-hand or right-hand configuration.

Do the Drains Go to the Floor or the Wall?

The floor. The installer needs room under the tub to fit the P-trap to the drain body, and the connection comes up through the floor, not out of the wall. There is roughly 3 inches of clearance under the tub, which is enough to run 2 inch PVC across to a house drain on the far side.

Where Does Ella's Plumbing End and My Plumber's Begin?

At the T body directly under the tub. Everything up to and including the T-type drain is Ella's; everything from there to the sewer is ordinary PVC and your plumber's work. There are no fixed directions for the run because the system is made to be flexible: your plumber routes it whatever way suits the space, as long as the run is short with few turns.

Can the Tub Be Removed Later Without Cutting Pipe?

Yes, if you plan for it. Ella does not recommend a specific brand, but a flexible P-trap or a no-hub coupling at the joint under the tub lets you detach the tub later. Keep the check valves and shut-offs accessible for the same reason.

Are the Supply Connections Pipe Thread or Hose Thread?

Pipe thread. The two braided supply lines that come with the faucet end in 3/4 inch female standard pipe thread, so your plumber stubs up with 3/4 inch male pipe thread. Each line is 5 feet long. Deeper: water supply lines and shut-off valves.

Do You Include Shut-Off Valves?

No. The braided lines are included; shut-off valves are not, and we recommend your plumber install them where they can be reached through an access panel. That makes any future faucet or cartridge service a quick job.

Is There a Drain Pump?

No. Ella tubs drain by gravity through oversized 2 inch drains and dual air vents built into the drain handles. There is no motor to fail, nothing to run in a power outage, and no pressure pushed into your home's drain lines. An average Ella tub drains in about 80 seconds under ideal house drain conditions, and the house drain must be in good shape for that to happen.

Does the LayDown Have Dual Drains?

No. The LayDown60 and LayDown72 use a single 2 inch threaded brass drain with a copper overflow and a supplied PVC 90 degree elbow. Order brass-drain parts for a LayDown, never a dual-drain kit. Deeper: the LayDown tub guide.

Ella's Bubbles: Dual Drain Technology and House Drain Connection
Chapters in this video
  1. 0:00 Dual Drain Technology Overview The video introduces Ella's Bubbles dual 2-inch, four-port drain system and its connection to a house drain.
  2. 0:20 Live Drain Demonstration A live demonstration shows water flowing through the dual 2-inch, four-port drains.
  3. 0:39 Drain Setup Images Actual images display a drain setup before and after the installation of the dual drain system.
  4. 1:01 House Drain Connection Options The video explains recommended house drain connections and how installers determine the best setup.
  5. 1:27 Easy Turn Drain Handles The easy turn drain handles are shown, which also function as dual air vents to maximize water outflow.
  6. 1:40 Single Drain and Gravity Driven System Some tubs feature an oversized single drain with emergency pull chain, and the gravity-driven system is highlighted.

This video shows the four T-type ports, a live demonstration of water leaving all four, and real before-and-after photos of an installation with dual P-traps and a new connection to the house main. It also shows a customer who used two of the four ports and capped the rest, and confirms that a 2 inch main is recommended while a T or Y into a 1.5 inch house drain still works. For which side of the tub the drains sit on, use the left-or-right configuration article linked above rather than the video.

Walk-In Tub With 4-Port Dual Drain System for Fast Draining
Chapters in this video
  1. 0:00 Ella's Bubbles Dual Drain System The technician explains the advantages of Ella's Bubbles' two two-inch drain system for fast draining.
  2. 1:20 Competitor's Power Drain System The technician describes a competitor's power drain system, highlighting issues with water overflowing back into the tub.
  3. 3:20 Another Competitor's Drain System The technician discusses a competitor's standard waste gate overflow and another's single oversized drain.
  4. 3:55 Ella's Bubbles 4-Port Dual Drain The technician explains how Ella's Bubbles' 4-port dual drain system offers maximum versatility for plumbing installation.

An installer who has fitted many walk-in tubs compares drain systems in the field. He points out that a 2 inch pipe carries roughly four times the volume of a 1.5 inch pipe, takes off the Ella door to show the two independent 2 inch drains, and explains why a powered drain that pumps water up the overflow is a headache in a real house while a gravity drain simply keeps working. Watch: Walk-In Tub With 4-Port Dual Drain System for Fast Draining: Voted Safest Tubs 2020 with chapters and a full transcript.

Common Questions

What size house drain do I need?
A 2 inch house drain is recommended for the fastest draining, since every Ella tub drain is 2 inches. If your home has a 1.5 inch line, the 2 inch tub drain reduces to it with a standard reducing fitting ahead of the P-trap, and the tub still drains well. See connecting the 2 inch drain to 1.5 inch house plumbing for the fitting choices.
Is there a special pipe I have to buy?
No. Everything up to and including the T-type drain body under the tub is Ella's, and past that point it is ordinary PVC pipe and fittings from any plumbing supply house. Caps for the unused ports ship with the tub, so nothing special has to be sourced.
Which drain on a dual-drain tub do I connect first?
It does not matter. Both are gravity drains on the same kind of T-type body, and the two drains are tied together under the tub, so connect whichever ports face your house drain and cap the others. Connecting all four ports drains fastest, two is the most common build, and one still works.
What if my plumber hard-piped everything and the tub sits a few inches off the wall?
That is fine. There are no fixed drain directions, because the system is made to be flexible and your plumber routes it whatever way suits the space, as long as the run is short with few turns. A flexible P-trap or a no-hub coupling at the joint under the tub gives you room to shift the tub and lets it be detached later without cutting pipe.
What size is the water feed?
The faucet's supply connections are 3/4 inch female pipe thread, so your plumber stubs up with 3/4 inch male pipe thread, and the two included braided lines are each 5 feet long. Your plumber decides the house pipe size behind those connections. The faucet's rated fill assumes good household pressure and flow, so talk it through with your plumber if your supply is on the weak side.
Are the check valves accessible after install?
They should be. Place the supply connections, shut-off valves and any check valves where an access panel reaches them, since shut-off valves are not included and we recommend your plumber install them. That way any future faucet or cartridge service is a quick job, and the tub can be detached later without cutting pipe.
The tub drains slowly. Is it the dual drain?
Usually not. Ella tubs drain by gravity through oversized 2 inch drains, so make sure the drain handles are fully open and have your plumber check the house drain, because a dual drain cannot fix a slow house line. An average Ella tub drains in about 80 seconds under ideal house drain conditions, and the house drain must be in good shape for that to happen. See tub drains slowly or not at all.
Does a single-drain tub still have the T-type body?
Yes. The Standard, Zen, Flow and Front Entry have one 2 inch gravity drain, and it still sits on a two-port T-type body. That means the house connection can come from either direction, with the other port capped, and the step down to 1.5 inch house plumbing is the same as on a dual-drain tub.
Do the therapy features need their own electrical line?
Yes. Therapy features require a dedicated electrical line brought to the tub so the system can be plugged in. Have your electrician plan that circuit at the same time your plumber plans the drain and supply rough-in, so both connections land where the access panel can reach them. If you have a question about your layout, call (800) 480-6850 or open a ticket at ellasbubbles.com/support.
Has the Master Bath Control box changed recently?
Yes. The Master Bath Control box is moving to a smaller housing, available in both 15 amp and 20 amp versions. The change affects only the overall size of the box, and the operation of the tub remains exactly the same. Your Ella dealer or the team at (800) 480-6850 can confirm which version shipped with your order.
What if the diverter knob falls into one of the drains?
On some tubs, such as the Monaco, the diverter valve knob can drop into one of the two 2 inch drains if it comes loose. Do not run the tub until it is retrieved, since the drain body sits directly under the tub where your plumber can reach it. Open a ticket at ellasbubbles.com/support with a photo, or call (800) 480-6850, and the team will help you with the next step.

Still have a plumbing question about your layout? Open a ticket at ellasbubbles.com/support with a photo of your rough-in, or call (800) 480-6850, and the team will help your plumber plan it.

About this guide. Answers in the Ella’s Bubbles Support Center are compiled from real conversations with tub owners, our technicians’ notes and the product documentation, then reviewed by our team. Tub models and options have evolved over the years, so a detail here may differ slightly from your exact tub. If something looks different on yours, send us your serial number and a specialist will confirm it for your model.

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