How to Install a Bathtub Diverter Spout Replacement

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This page covers bathtub diverter spout replacement how to install steps, using two Moen installation guides, a Kohler troubleshooting page, an EPA technical sheet and a Moen product page. A diverter sends water up to a shower head or hand shower when you pull its knob, so a faulty spout affects your shower as well as your tub. The sources cover shut-off, pipe checks, set-screw tightening and drip behavior. They do not cover every diverter design, so the gaps are listed further down.

Quick answer

• Turn the water off before you remove anything. Moen’s guide says to always turn the water supply off before removing an existing faucet or disassembling a valve.
• Check the pipe end for sharp edges or burrs. Moen says this check comes before any tub spout installation.
• Find out whether the spout is threaded or slip-fit. Moen describes threaded spouts that screw onto 1/2 inch male pipe threads, and slip-fit spouts that use a set screw with no threaded adapter.
• Tighten in passes. Moen’s hand shower steps call for barely tightening the set screw first, then finishing with a 3/32 inch hex wrench.
• Know that some drip can be normal. Kohler says a small amount of water may drip from the tub spout when the water is diverted, on Rite-Temp valves that have no positive shut-off diverter. That statement applies to those valves only.

How we chose

The sources in this post were picked against three conditions. They had to come from a manufacturer, a government agency or a manufacturer support site. They had to address tub spout installation or diverter behavior directly. And every sentence quoted from them had to appear word for word in the saved copy. Retail listings and blog posts were not used for installation steps, and they were not used for any figure in this post. A Delta instruction PDF returned a bot-check page instead of its text, so it was not counted.

Five pages were opened on 2026-10-22 and are listed in full at the end of this page. Moen’s INS10269A guide covers a hand shower and tub spout kit. Moen’s INS2150 guide covers valve and tub spout installation. Kohler’s page covers drip and back-pressure symptoms on Rite-Temp valves. The EPA sheet covers WaterSense flow limits and devices that can sit on a tub spout diverter. Moen’s product page describes how a handheld shower on a bracket connects. None of these is a guide to a diverter spout alone, and that shapes what this post can say.

Before you start

Gather the tools and parts that the instruction sheets name. Moen’s hand shower guide lists a 5/32 inch and a 7/64 inch hex wrench in its parts list, and it includes thread seal tape in the box. Moen’s valve guide lists pipe joint compound and a key hole saw in its tool list, and it calls for thread seal tape in its steps. Have the model number of your spout or valve ready, because each guide is written for specific models and none of them fits every product.

The first job is the water. Moen’s kit guide opens its removal tips with the instruction to turn the water supply off before removing an existing faucet or disassembling the valve, then to open the faucet handle to relieve pressure. Do this before you loosen the old spout. The sources do not say how long the supply should stay off, and they do not describe a way to confirm the supply is closed beyond opening the handle.

If you have not yet picked the diverter itself, see Best Shower Diverter for the product side. This post covers the install steps only.

Step-by-step: installing the replacement spout

Step 1: Check the pipe end

Moen’s kit guide says: “Ensure there are no sharp edges or burrs on end of pipe before tub spout installation.” The check comes before the spout goes on, so treat it as a required step rather than an optional one. The guide does not say what a burr does to the fit, and it does not say how to smooth one. If the pipe end is rough, deal with it before you move on, and check your manual for the method it recommends.

Step 2: Identify the spout type

Moen’s valve guide describes two installation types. For threaded spouts, the guide says that IPS spouts are “designed to screw onto a pipe with 1/2 inch male pipe” threads. It also says that a threaded spout connects to the valve through 1/2 inch pipe or 1/2 inch copper tubing with a threaded adapter. A slip-fit spout works differently. The guide says: “Some models may feature a slip fit installation with no threaded adapter in the tub spout.” The sources do not explain how to tell the two types apart by looking at an installed spout, so read the packaging or the manual for your model.

Step 3: Measure pipe length only for new pipe runs

Moen’s valve guide gives a pipe length formula for a threaded tub spout: “(y) + (x) + 1/4″ = Pipe Length”. In that guide, y is measured from the inside elbow shoulder to the wall, and x is measured from the threaded adapter inside the tub spout to the base of the spout. Then 1/4 inch is added. The formula belongs to a valve installation, so use it when you are running new pipe. The sources do not say whether it applies when you only swap a spout onto existing pipe, and that is the most common replacement case.

Step 4: Set the spout on the pipe

Moen’s hand shower kit guide describes the spout seating in two steps. First: “Slide Tub Spout (G) onto pipe inverted.” Then: “Rotate Tub Spout (G) right side up.” These steps come from a kit guide, so they describe that kit’s spout. Compare them with the manual for your own spout before you follow them, and do not assume every spout seats the same way.

Step 5: Tighten the set screw in passes

The kit guide says: “Using a 5/32″ hex wrench, barely tighten set screw.” It then says: “Finish securing tub spout with 3/32″ hex wrench.” Moen’s slip-fit valve guide describes the same order in its own terms: slightly tighten the set screw, rotate the spout to its final position, then fully tighten the set screw. Its wording is: “Rotate tub spout to final position and fully tighten set screw in place.” The sources give no torque figure, and they do not say how far the set screw should turn after the light pass.

Step 6: Connect the hand shower side

If your diverter feeds a hand shower, the connection on that side has its own parts. Moen’s product page says: “A handheld shower on a bracket is a showerhead that has a flexible hose threaded to one end.” It goes on to say that the other end of the hose threads onto the handheld bracket, and that the bracket “threads to the shower arm.” Follow the hose and bracket steps in your own manual. The sources do not describe the diverter knob, its stem or its seal, so do not assume the spout steps cover those parts.

If your tub faucet already feeds a hand shower, the choice of hand shower affects how this connection goes. See Best Hand-Held Shower Head for Tub Faucet for that comparison, and see How to Install a Handheld Shower Head With Diverter for the hose-and-head side of the same setup.

Step 7: Check the connections after the water is back on

Once the water is back on, check the spout, the connections and the shower head for leaks. Kohler’s troubleshooting page describes a case where water comes out of both outlets at once, and it says that “Using materials other than recommended will cause back-pressure and cause water to flow from the showerhead and tub spout simultaneously.” The same page gives a pipe rule for Rite-Temp valves: “Only 1/2″ copper pipe can be used to connect the valve and the tub spout.” It also says that “If PEX is installed, a delayed flow of water may occur.” These statements apply to Rite-Temp valves. For other valves, follow that valve’s manual.

Checks after installation

Use the diverter with the water on and watch both outlets. Kohler’s page describes a small, permitted drip from the tub spout when water is diverted to the shower head, but only for Rite-Temp valves. Its wording is: “There is a small, permissible, amount of water that may drip from the tub spout when the water is diverted to the showerhead.” If your valve is a different model, do not treat the drip as normal without checking its manual. A drip from the spout that continues when the diverter is in the tub position is a different question, and the sources do not cover it.

If water comes from both outlets at the same time, the first things to check are the pipe material and whether the valve type matches the guide you are following. The sources point to back-pressure from non-recommended materials as the cause in Kohler’s case, and they do not list other causes.

Shower head and flow context

The diverter matters for flow because it sends water to a shower head or hand shower. Moen’s kit guide states: “Shower heads: Standard 9.5 L/min (2.5 gpm) max. and High Efficiency 7.6 L/min (2.0 gpm) max. or less.” The EPA sheet says WaterSense labeled showerheads have a maximum flow rate of 2.0 gallons per minute, which it describes as “less than the current federal standard.” Those are the limits the sources give. If you also replace the head, check its gpm marking against them.

The EPA sheet also covers thermostatic shutoff valves, or TSVs. It describes TSVs as slowing water to a trickle once hot water arrives, and says they can be placed on a showerhead or a tub spout diverter. That is a separate device, not a spout replacement. Check whether your setup includes one before you attribute slow flow to the spout. Moen’s product page also uses “Diverter tub spout” as a feature label for some of the handheld products it lists, which confirms that diverter spouts are a recognized product feature but adds no install detail.

If you are choosing a new head to go with the spout, see Best Water-Efficient Hand-Held Shower Heads. The flow limits above apply to that comparison too.

Mistakes the sources warn about

• Working on the spout with the water still on. Moen’s guide says to turn the supply off first.
• Skipping the pipe check. Moen says to check for sharp edges or burrs before the spout goes on.
• Mixing threaded and slip-fit steps. A threaded spout uses a threaded connection, while a slip-fit spout uses a set screw and no threaded adapter.
• Using the wrong pipe material. Kohler says only 1/2 inch copper can connect the valve and the tub spout on Rite-Temp valves, and that other materials cause back-pressure.
• Treating every drip as the same. Kohler’s permitted drip applies to Rite-Temp valves without a positive shut-off diverter, not to every valve.
• Fitting a shower head that exceeds the limits the sources give. Moen lists 2.5 gpm as the standard maximum, and EPA’s WaterSense cap is 2.0 gpm.

What we could not verify: what the sources do not say

• How to remove a stuck, corroded or glued-in spout. None of the five pages covers removal beyond the shut-off step.
• How to replace the diverter knob, stem or seal. The sources describe the spout and hose connections, not the diverter mechanism.
• Torque values. The guides say “barely” and “slightly” tighten the set screw, with no number given.
• How to tell a threaded spout from a slip-fit spout by sight. The sources name the two types but do not describe identification.
• Pipe length for a spout swap on existing pipe. The length formula is written for a valve installation.
• Thread sizes for every brand. The 1/2 inch IPS figure comes from one Moen valve guide, and other manufacturers may differ.
• Flow for a diverter spout. The flow figures in this post are limits for shower heads, not for spouts.
• When a licensed plumber is required. The sources do not give a rule for that.

FAQ

Do I need to turn the water off to replace a tub spout?

Yes. Moen’s guide says to always turn the water supply off before removing an existing faucet or disassembling the valve. The sources do not say how to confirm the supply is fully closed beyond opening the faucet handle to relieve pressure.

How do I know if my tub spout is threaded or slip-fit?

The sources describe both types but do not explain how to tell them apart by sight. A threaded spout screws onto 1/2 inch male pipe threads, and a slip-fit spout needs a set screw and no threaded adapter. Check the packaging or the manual for your model before you buy a replacement.

Why does water come out of the spout when I pull the diverter?

Kohler’s page says that on Rite-Temp valves, which have no positive shut-off diverter, a small, permissible amount of water may drip from the tub spout when the water is diverted to the showerhead. If water comes from both outlets at once, the page points to back-pressure from non-recommended pipe materials. The sources do not explain other causes, so check the manual for your valve if the flow pattern does not match these cases.

Can I use PEX or another pipe for the spout connection?

For Kohler Rite-Temp valves, the sources say only 1/2 inch copper can connect the valve and the tub spout, and that PEX can cause a delayed flow of water as it expands. Moen’s valve guide says to use 1/2 inch copper or IPS pipe only. Check your valve’s manual before you choose a pipe material, because the two guides are for different valves.

Does a new spout change my shower flow?

The sources do not give a flow figure for a tub spout or a diverter. They do give limits for shower heads. Moen’s kit guide lists standard heads at 2.5 gpm maximum and high-efficiency heads at 2.0 gpm or less. EPA says WaterSense labeled showerheads have a maximum flow rate of 2.0 gpm. If you replace a head at the same time, check its marking against those limits.

Do I need to replace the shower arm too?

The sources do not say. The only arm-related detail in the pages opened is that a handheld bracket threads to the shower arm, according to Moen’s product page. Whether the arm needs replacing depends on its condition and on the manual for your model, and the sources do not address either point.

When should I call a professional instead of doing this myself?

The sources do not give a rule for when a licensed plumber is needed. Moen’s kit guide lists “Please Contact Moen First” for installation help, missing parts or replacement parts, with a phone line for each region. If the pipe or valve looks damaged, or the steps in your manual do not match your model, that support line is the next step the sources point to.

Bottom line

Turn the water off, check the pipe end, identify whether the spout is threaded or slip-fit, and tighten the set screw in passes. The sources support that order for Moen spouts and give a clear pipe rule for Kohler Rite-Temp valves. If your spout or diverter is a different design, the manual for that product governs, and the gaps listed above apply.

Sources

• Moen, Please Contact Moen First, Installation Guide, INS10269A (5/14). Hand shower and tub spout kit. https://assets.moen.com/shared/docs/instruction-sheets/ins10269a.pdf (opened 2026-10-22)
• Moen, valve installation instructions, INS2150. Threaded and slip-fit tub spout steps and pipe requirements. https://assets.moen.com/shared/docs/instruction-sheets/ins2150.pdf (opened 2026-10-22)
• U.S. EPA, WaterSense Technical Reference Manual for Labeled Homes, Showerheads Technical Fact Sheet, EPA-832-F-23-016 (July 2023). https://www.epa.gov/system/files/documents/2023-08/ws-homes-TRM-4-ShowerheadsTechSheet.pdf (opened 2026-10-22)
• Kohler Assist, Rite-Temp Valve Dripping from Showerhead or Spout. https://assist.kohler.com/en/valves-shower-bath/Rite-Temp-Valve-Dripping-from-Showerhead-or-Spout (opened 2026-10-22)
• Moen Solutions, Handheld on a Shower Arm-Bracket. https://solutions.moen.com/Article_Library/Handheld_on_a_Shower_Arm-Bracket (opened 2026-10-22)