Why Does my Tub Faucet Keep Running When I Turn on My Shower

Why Does my Tub Faucet Keep Running When I Turn on My Shower

header why does my tub keep running when I turn on my shower

Everything You Need to Know about your Shower's Diverter

Showering is something you probably (hopefully!) do fairly frequently. You’re no stranger to stepping in the shower, turning on the tub faucet, and adjusting the taps to get the perfect water temperature. Nobody has to tell you how to stop the water from coming out the tub spigot and have it come out the showerhead instead, right? Of course not! But have you ever honestly thought about the process that goes on to get that water to the perfect temperature and into the showerhead for your shower every day? We’re going to guess the answer to that question is probably not.

However, if you’ve ever turned your shower on but noticed that there was still water running from the tub’s faucet, you may have wondered what was wrong with your shower. You’d probably be especially frustrated by the lack of pressure coming from your showerhead, because it makes it difficult to shower properly. That’s also probably why you’re reading this article today – to see why it happens and maybe learn how to fix it.

On today’s edition of Ask a Plumber, we researched what causes your tub’s spigot to keep running even when you turn on your shower. Although it could be that you have a lot of highly pressurized water (which is something you should check with a plumber), the main culprit of this mess is a shower diverter valve.

What’s a Shower Diverter Valve?

Valves are prevalent in your plumbing. They are what you use to turn on your sink, garden hose and tub. They even help determine what temperature your water is when you turn on the sink or shower! When you move the lever of a valve, you open the pipe for water to come out of the spigot.

As for your shower, you’ve probably never heard it called a diverter valve, but it’s what you turn, push or pull on to change the water coming from your tub’s faucet to your showerhead. It does exactly what it’s named for: it diverts (changes direction) water from one place to another.

download diverter graphics

The only problem with shower diverter valves is they don’t last forever, and there are many times, like all of the other components of your home, when they fail from old age and normal wear and tear.

There are two types of shower diverter valves.

Three Valve Shower Diverter

download diverter graphics

A three valve shower is one that has three different handles that you turn to open or close the valves. One handle opens the hot water valve, one opens the cold water valve and the third (generally in the middle of the temperature valves) diverts the water into the spigot or up to the shower head.

A three valve shower is one that has three different handles that you turn to open or close the valves. One handle opens the hot water valve, one opens the cold water valve and the third (generally in the middle of the temperature valves) diverts the water into the spigot or up to the shower head.


As you turn the valves for the hot and cold valves, depending on the temperature you want the water to be coming out of your spigot, you’ll open the valves more or less. Once you get the right temperature, you can keep the water running into your tub, or twist the valve 180 degrees to divert the water up into the showerhead.

download diverter graphics

When it’s turned down, having the water pour into the tub through the spigot, the valve is open, and lets water through. When the handle is turned 180 degrees, the valve moves forward, and a rubber washer plugs the spigot of the tub so no water can get through.

. Three Valve Diverter Diagram 

download diverter graphics

 Instead, the water is forced through a small number of holes in the valve, which builds pressure, sending the water up through the shower’s pipe and out of the showerhead.

The diverter valve looks like this:

download diverter graphics

Tub Spigot Diverter Shower

There are a number of different ways this shower looks. Some showers have two handles that regulate temperature, which open the cold and hot water lines separately. The water mixes together before coming out of the spout. Other showers have one handle that opens both of the water lines, and depending on how far the handle is turned, determines how much of the two water lines are opened, and how hot or cold the water is, mixing the water temperatures. Either way, the diverter valve is generally found on the spigot of the tub.

download diverter graphics
This diverter valve is something you pull up or switch over to plug the water from coming into the spigot, diverting it up into the showerhead. When the diverter is pulled, is pulls a rubber (or sometimes plastic piece) into the whole where the water pours through, plugging the escapes for the water.

tub spigot diverter valve diagram

download diverter graphics

The water pressure builds up, keeping the diverter in place and pushing the water up the shower pipe, through the showerhead.

Why would my diverter not be working?

Although diverter valves are a fairly simple way to change water from the tub to the shower, if they break down and fail, they could cause other major problems in your bathroom. Unfortunately, just like everything else in your home, they break down eventually through normal wear and tear. (That’s why you have a home warranty on your house, right?) There are a few reasons why your shower may be having water flow through both the tub’s spigot and the showerhead at the same time (or one not at all). If you find that you’re having these problems, you may need to have your diverter replaced.

(It’s important for us to mention that if you’re a home warranty customer, you won’t have to do any investigation into why your diverter valve isn’t working – in fact, if you try to investigate the problem yourself and fail, the repair may not even be covered by your home warranty! If you call your home warranty company right away, though, you could only have to pay a $60 service call fee.)

Here are some reasons why a diverter may be failing to bring water into a showerhead:

Blocked Diverter:

In both types of diverter valves, if there’s something that’s blocking the diverter from closing all the way, or opening all the way, it could cause water to pour out of both spigots at the same time.

If you have a spigot that has the diverter directly inside of the spigot, you can see if there is something that’s blocking the diverter from closing all the way. You may need to soak the faucet in vinegar overnight to soften calcium build-up, or clean it out with a small soft brush.

why tub spigot diverter may not work

download diverter graphics

With the three-valve shower, if you can take the shower faucet off easily, you can try and open the valve and see if there are any blockages within the valve and brush them off with a clean cloth.

Broken Washer

Some diverters rely heavily on rubber or nylon washers to make sure the holes to the spigot are properly closed. If these washers crack, fall apart or get bent, they could be causing the problem with the diverter. If you see a broken or cracked washer, this is something that will need to be replaced.


Sometimes the threads on the crew that connect the spout to the pipe can corrode or the spout’s finish could flake of and cause blockages within the shower. If this is the case, and the faucet isn’t replaced, it could cause water to leak out on the wall behind the shower, which could cause rot, mold, or mildew.

If corrosion or a broken washer is the cause of your diverter woes, you’ll probably need to replace the diverter valve. Not sure how to do that? Not to worry! Our next article is about how to replace the diverter valve on your shower

replacing a shower diverter valve button

Wait! Are You a Landmark Home Warranty Customer?

If you’re having problems with your diverter valve, listen up! Don’t take your shower apart to see if there’s a problem. Because you have a home warranty, if your shower diverter valve has failed from normal wear and tear, you can have everything fixed and paid for, for a $60 service call fee! If you try to do-it-yourself, then you may not have the repair or replacement covered.If you're not a home warranty customer and you have no interest in saving hundreds of dollars on home repairs like broken diverter valves, go onto your next article: how to replace a shower diverter valve

replacing a shower diverter valve button

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