shower-diverter-valve

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A shower diverter valve sends water either to the tub spout or up to the showerhead. When it fails, the shower may keep running from the spout, the showerhead may lose pressure, or the diverter lever may not stay up. This guide sets out what the diverter does, how to tell whether the diverter or a different valve is the cause, and what the two sources say about wear. The sources do not give a diverter fix that fits every faucet, and this guide does not give removal or replacement steps, because those involve plumbing work beyond swapping a showerhead.

Quick answer

A shower diverter is a valve that controls the water flow in your shower system, according to This Old House.
Moen describes a transfer valve as the part that “is designed to divert water in a shower.” Moen also says a transfer valve by itself cannot control water flow or temperature, so it works with a second valve.
Reduced showerhead pressure, water that keeps flowing from the tub spout, and a diverter that is hard to pull up are the symptoms This Old House lists.
This Old House names worn washers, mineral buildup from hard water, and broken diverter stems as the common causes.

What a diverter does

This Old House says that a shower diverter “redirects water from the tub spout to the showerhead when you turn or flip it.” That lets one set of pipes feed both a bath and a shower. The article also describes the diverter as a small but integral part of the bathroom plumbing system, one that controls the flow between the bathtub faucet and the showerhead.

Moen uses different terms for a similar job. Its article describes a transfer valve in a custom shower system, often called a Vertical Spa. In those systems, the transfer valve “is usually installed above the mixing valve and characteristically has a smaller trim plate.” Moen says the two valves have separate jobs. The mixing valve “is housed behind the handle or knob in your shower and is responsible for turning the water supply to the entire system on and off.” The transfer valve decides which shower device receives the water.

Moen also says that showerheads and handheld showers are “designed to provide varying flow rates.” Its page advises checking the flow rate of the device with the complaint before repairing or replacing anything in the system. Readers comparing handheld flow rates can look at our guide to water-efficient handheld shower heads.

Types of shower diverter

This Old House lists three main types of diverter that a reader may find in a bathroom:

Three-valve diverter: separate hot and cold knobs, plus a third valve that works as the diverter.
Tub spout diverter: a lever on the tub spout that controls the flow. The article says this type is common in bathtub and shower combinations and in older homes.
Two-valve diverter: one knob for water temperature and another that acts as the shower diverter.

The article’s advice is to “Identify your diverter type before attempting to fix it.” The type decides which part is in reach and which parts are likely to fail.

Which part is failing

Symptoms do not always point to the diverter. Moen separates the two possible causes by what stops working:

One device stops working: Moen says that when “one showering device not operating or a noticeable loss of water pressure” appears, “there is a problem with the transfer valve.”
The whole system loses water, or one temperature is weak: Moen says that “a shower system that exhibits no water to the entire system or a decrease in temperature specific water (no hot or no cold) indicates there is a problem with the mixing valve.”

This Old House lists three signs of a faulty diverter:

Difficulty in operation. The article says that if the diverter “is hard to pull up or doesn’t stay in position,” the cause may be “a worn-out washer or a damaged diverter stem, both of which are repairable issues.”
Leaks and drips. The article names worn washers, cracked components and a loose diverter system as possible causes.
Water flow problems. The article says that if “reduced water pressure in your showerhead or water continuing to flow from the tub spout when the diverter is engaged” appears, “it’s likely time for a repair.”

Moen’s troubleshooting is written for its own valve families. The sources do not say whether its symptom chart applies to a standard tub spout diverter, so a reader should use it as a general guide to the two-valve logic, not as a model-by-model diagnosis.

What causes the wear

This Old House says that “Shower diverter problems commonly stem from worn-out washers,” and names mineral buildup from hard water and broken diverter stems as the other two causes. On washers, the article gives a timeframe: “Washers usually only last for about five years before they need replacing.”

Mineral buildup is the second cause the article describes. It says that “If you live in an area with hard water, mineral buildup is a common cause of broken shower diverters.” The article says the buildup can sit inside the diverter housing as well as on the outside of the spout and showerhead.

A broken stem is the third cause. The article describes a bent, damaged or broken stem as a part that needs replacing, and says that how to replace it “depends on your faucet model.” The sources do not give a stem part number or a universal method.

Checks before any work

Both sources agree that the water should be off before any part of the diverter is handled. This Old House says to “Locate the shutoff valves for your shower before starting work on the repair,” and that the valves are “usually situated beneath the faucet handle or behind an access panel faceplate.” The article tells readers to turn those valves clockwise to stop the water.

Moen’s advice is to check flow first. Its article says, “Before replacing or repairing your shower system, please confirm the flow rate (GPM/gallons per minute) of the device that is experiencing the reduced water flow.” If a showerhead or handheld shower is restricted, the sources suggest looking for blockage in the device before replacing the valve. Moen says that for a showerhead or handheld, the device should be removed and the water turned on to check the flow, and that if flow is normal with the device off, the device should be rinsed and tested again.

Maintenance between repairs

This Old House recommends cleaning the showerhead and tub spout to limit mineral buildup. It says to “Use a mixture of equal parts white vinegar and water to soak these components monthly,” and to “Gently scrub away any visible deposits with a soft brush for a clean finish.” The article says this routine can help extend the life of the diverter, though it does not say how often the diverter itself needs to be checked.

The soak applies to the showerhead and the tub spout. It does not cover the diverter mechanism in the same way, and the article does not say whether vinegar is safe for every finish.

When to call a plumber

This Old House advises calling a plumber “If you’ve attempted repairs and the problem persists, or if you encounter issues within the wall behind the shower.” The article also lists signs that the problem may be larger than the diverter: “If you notice sudden changes in water pressure throughout your home, hear unusual noises in your pipes, or see water stains on walls or ceilings, these could indicate larger plumbing problems that a plumber should inspect.”

The article also says that once the spout is off, a reader should look at the pipe and the surrounding area “for signs of corrosion or moisture before reassembling.” A reader who sees corrosion or moisture behind the wall should stop and call a plumber, since this guide does not cover that work.

Replacement parts for Moen valves

Moen’s page matches replacement transfer valve cartridges to valve model numbers. Under the heading “Replace the Transfer (Diverter) valve cartridge:” it lists, for example, “2060 Cartridge: 3500 Independent Transfer Valves,” and several other cartridge numbers for other model numbers. A reader with a Moen valve should match the model number of that valve to the list. The page also points to solutions.moen.com for more repair detail for each faucet family.

A shower with a fixed head and a handheld can route water between them through a transfer valve. Readers comparing setups can see the choices in our guide to dual shower heads with a slide bar. Moen says that once the mixing valve is on, the transfer valve handle “can be rotated to activate the individual shower devices to operate independently,” and that some valves offer a setting where “two or more of the devices will work simultaneously.”

FAQ

Why won’t my shower diverter stay up?

This Old House says that “A shower diverter that won’t stay up is most likely caused by an issue with the rubber washer inside the mechanism.” The same article says the washer usually lasts about five years, and that a worn washer is the most common diverter issue it describes.

What is the most common problem with a diverter valve?

According to This Old House, “The most common problems with a shower diverter valve are due to wear and tear, mineral buildup, or cracks in the diverter housing.”

Do I need to turn off the water first?

This Old House says, “Yes, you need to turn the water off to replace a shower diverter.” The article’s reason is that turning the water off “will prevent unexpected water flow and reduce the risk of water damage.”

Should I call a plumber?

The article’s answer is that if a reader is “unsure or uncomfortable about doing the work yourself, it’s best to contact a professional plumber.”

How we chose

This guide is built on two pages, both opened on 2026-10-28. The This Old House page covers diverter types, symptoms, causes and maintenance for a bathroom shower. The Moen page covers how transfer and mixing valves differ and gives a symptom-by-part guide. Both pages describe the diverter part in their own words and both name the parts that fail. The choice was made on those criteria. It is not a ranking of products or brands.

Other pages on the same sites were not used for this guide. Moen’s pages on single-handle cartridges were not used here, because they describe a different valve type.

What we could not verify

What the sources do not say

The sources do not say how long a diverter lasts beyond the washer timeframe, and do not give a cost or part price.
Moen’s page is written for Vertical Spa and multi-device systems. It does not say whether its symptom chart applies to a single tub spout diverter.
Neither source says whether a vinegar soak is safe for every finish on a showerhead or spout.
The sources do not say how to tell from the outside whether a particular diverter has a worn washer, a broken stem, or both.
This Old House says the stem replacement “depends on your faucet model,” and it does not give a method for each model.

Sources

This Old House, “How To Repair a Shower Diverter,” https://www.thisoldhouse.com/bathrooms/how-to-repair-shower-diverter (opened 2026-10-28)
Moen Solutions, “Shower Faucet: Low Flow- Independent Transfer Valves,” https://solutions.moen.com/Article_Library/Shower_Faucet%3A_Low_Flow-_Independent_Transfer_Valves (opened 2026-10-28)