What are supply lines on a walk-in tub or shower faucet?

Supply lines are the two hoses that bring hot and cold water from your home's plumbing to the faucet on a walk-in tub or shower. On an Ella walk-in tub they are the two 3/4 inch by 5 foot braided lines packed with every 2-piece and 5-piece fast-fill faucet set, as described in What Is a Fast-Fill Faucet on a Walk-In Tub?. The faucet itself is mounted on the deck at the factory, but the lines are connected by your installer on site, so knowing what they are helps you plan the rough plumbing before the tub arrives.

What a Supply Line Does

An Ella walk-in tub fills through a deck-mount faucet that the bather or a caregiver opens and closes. There is no auto fill control and no pump on the fill side, as Does Ella Offer Auto Fill or Emergency Lowering Features on Walk-In Tubs? explains. Water has to travel from the pipes in your wall or floor up to that faucet, and the supply lines are the final stretch of that path. Each set has two lines because the faucet mixes hot and cold. On the 2-piece set the single lever moves left for hot and right for cold, and on the 5-piece set the red handle is hot and the blue handle is cold, so one line feeds each side.

It helps to separate supply lines from two other sets of tubing on the tub, because owners often use the word loosely.

• The hand shower hose. Both faucet sets include a pull-out hand shower that rides on its own 5 foot braided hose with a back-flow prevention valve. That hose carries water away from the faucet to the handset, not into the faucet, and it is matched to the set. The 5-piece hose does not fit the 2-piece faucet.
• The air and water lines under the deck. On a tub with air or hydro massage, a network of tubes runs behind the shell to the jets. The under-the-deck piping video walks around the back of a tub and shows how those bundled lines are routed, glued and grounded. They belong to the therapy system, and the Auto Purge that blows the air lines dry 20 minutes after the air pump is turned off is cleaning those lines, not the supply lines.

What Comes in the Box

Both Ella fast-fill sets include the extendable multi-function hand shower, two 3/4 inch braided supply lines and the diverter. The 2-piece set is the single-lever faucet designed for 16 gallons per minute at 60 PSI, and the 5-piece set with separate hot and cold levers is designed for 18 gallons per minute. Two things are worth knowing before delivery day.

1. The faucet ships assembled on the deck but not hooked up to the supply lines. This is deliberate, so the tub can leave the factory fully drained. Your installer makes the connection once the tub is in place.
2. Shut-off valves are not included with the set. The team recommends easily accessible shut-off valves near the tub, so settle their location with your plumber while the wall or floor is still open.

The hot water supply video makes the same two points in under two minutes. It recommends 3/4 inch supply lines with easily accessible shut-off valves, and it reminds you that 5 foot supply lines are included when you order an Ella 2-piece or 5-piece fast-fill faucet set. It also shows where on the Ella website to find each tub's water capacity in gallons, occupied and unoccupied, so you can check your hot water supply against the tub you are considering.

Why 3/4 Inch Lines Matter for Fill Time

The gallons-per-minute figures printed for the faucets assume 60 PSI and ideal plumbing. In real homes, fill time runs 7 to 15 minutes depending on the tub size and your water supply, and How long does it take to fill a walk-in tub? breaks down what sets that number. The supply lines are one link in a chain that also includes:

• House water pressure and the size of the pipes feeding the bathroom.
• The distance from the water heater to the tub.
• Hot water being drawn elsewhere in the house at the same time.
• The occupied capacity of your model, since you displace water once seated. Most standard-size Ella tubs hold 65 to 107 gallons unoccupied, and you will typically use 30 to 75 gallons per bath.

A fast faucet only helps if the water stays warm for the whole fill. The team's general guidance is a 75 gallon or larger water heater, and ideally the maximum capacity heater available for your house. The largest tubs, such as the ShaK and Big4Two, may require a dedicated additional heater, and a tankless heater should be rated at 11 gallons per minute or more. Have your contractor look at pressure, pipe runs and the heater together rather than at the supply lines alone.

Supply Lines When You Use Your Own Faucet

The supply lines described above come with the Ella faucet sets. Every seated Ella tub is normally ordered with its fast-fill set, but there are cases where a customer-supplied faucet is used, and Using Your Own Faucet covers each one. The LayDown60 has no faucet option at all and always needs a customer-supplied faucet, usually wall-mounted. The LayDown72 lets you choose No Faucet, 2-piece or 5-piece at order time. On other seated models a no-faucet order is possible on some tubs, but the deck still arrives drilled for the Ella set. In any of these cases your plumber plans the supply connection around the faucet you choose rather than around the Ella lines.

Supply Lines Behind a Shower Wall

The same term comes up with Ella's multi-piece gel coat roll-in showers, where the supply lines and valve sit behind the back wall panel. Those panels can be cut on site to route supply lines or clear an existing valve, and installers do this regularly. The panels are wood and fiberglass with steel reinforcing rod around the perimeter, so the panel cuts with a jig saw or fine-blade circular saw, while any rod in the path needs a reciprocating saw with a steel-cutting blade. Before cutting through a rod, send a photo of the location with your model number to the team, because whether a given rod can be cut depends on where it sits in that unit. Cutting a Roll-In Shower Back Wall Panel to Route Supply Lines or Clear a Valve has the full sequence, including the dry-fit and marking steps.

Watch: Inside the Build: Under-the-Deck Piping of Our Walk-In Tubs | Voted Safest 2020 | Ella’s Bubbles with chapters and a full transcript.

Related Guides

• Water Supply Lines, Shut-Off Valves, and Pipe Size for a Fast Fill
• Faucet Supply Hose Leaking Under the Deck: Access, Identification and Replacement
• Replacement Hot and Cold Faucet Supply Lines: Sizes, Threads and Where to Get Them

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