In this video, This Old House plumbing and heating expert Richard Trethewey helps a homeowner dealing with a showerhead that leaks every time they fill their tub.
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Plumbing and heating expert Richard Trethewey takes us on a road trip to solve a homeowner’s shower problem. Every time the homeowner turns on their tub spout, water also flows out of the showerhead. After inspecting the issue, Richard finds a problem with the water pressure and provides the homeowner with a simple (and free) fix.
Water coming out of a showerhead every time the tub is filling can be an annoying issue. With modern shower valves, the issue is typically that not enough of the water can exit the tub spout, and there can be a couple of causes. Here’s a helpful way to troubleshoot the issue.
How Modern Shower Valves Work
Before pinpointing the issue, it’s important to understand how modern shower valves work. These valves look like 4-way connections, with hot and cold water coming in from the sides of the valve, and exiting into the tub through the bottom outlet. Inside that outlet are two orifices. The larger orifice supplies the water to the tub spout.
Under normal conditions, with the tub spout open, the water simply flows from the orifice and out of the tub spout. With the tub spout shut, the water backs up and travels back to the shower valve, passing through the smaller orifice. From there, it travels straight up and out of the showerhead.
Why Water Might Leak from the Showerhead
If the tub spout is open and water is leaking from the showerhead, there are generally two causes. The first cause is that the tub spout’s guillotine-like gate is stuck or partially obstructed. When this is the case, all of the water cannot exit the tub spout, causing it to back up and overflow out of the showerhead.
The other possible cause is that there is simply too much water pressure for all of the water to exit the tub spout. When this is the case, the backpressure will cause water to exit through the smaller orifice and out of the showerhead.
How To Tell Which is the Case
The easiest way to tell if it’s an issue with the tub spout or water pressure is to take the tub spout out of the equation. Do this by removing the tub spout from the plumbing, either with an Allen key or by unscrewing the tub spout, depending on the model.
Next, run the water at full force. If the water stops coming out of the showerhead, there is likely an issue with the tub spout itself. If water continues to flow from the showerhead, there is too much pressure in the system.
How To Solve It
If the tub spout is the issue, simply purchase a replacement tub spout and install it. Test it to make sure that it works properly. If the shower head still leaks with the new spout, it might be time to lower the pressure.
If the pressure is the issue, there are some simple fixes. If the pressure in the rest of the house is okay and the only place high pressure is causing an issue is the shower, simply find the control valves and throttle them back slightly until the shower runs properly.
If the pressure is too high throughout the whole house, adjust the pressure-reducing valve until the pressure levels are more reasonable. This valve looks like an upside-down cone with a bolt sticking out of the top, and users can adjust the pressure by turning the bolt in or out.
Where to find it?
Richard troubleshoots how to repair a homeowners water pressure valve for their tub and shower.
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How To Troubleshoot a Leaky Showerhead | Ask This Old House
17 Replies to “How To Troubleshoot a Leaky Showerhead | Ask This Old House”
What if you have a well water supply living in a rual area ?
complaining about the shower water pressure being too high…. first-world problems…. ????????
I just installed a new shower & tub faucet and have the same issue. I was worried that I had a defective kit.
I had the same issue. Problem wasn’t the water pressure. Problem was that the valve on my bathtub was placed high as if it were a shower shortening the distance from the valve to the shower head. The same issue seems to be the case here. In a bath tub the distance from the valve to the bath spout shouldn’t excess 11 or 12 inches. This leaves a longer pipe from the valve to the shower heard. Water will still climb up this pipe but there wouldn’t enough pressure to go all way out of the shower head. Reducing the water pressure didn’t work for me as water was still coming out.
I love the way you guys set up demo's to teach people what is going on. Thanks!
Using a helper, they could probably open the valve in the basement a little more until just before it starts coming out the showerhead.
Follow-up with homeowner: "Richard's solution worked, no more leaky shower head. I turned the valve back up to high so I can take a shower in something more than a sea mist, but at least I know I'm not losing my mind." ????????
I have a similar, but opposite issue with mine. I have a similar setup, with the single dial for water flow and temp and the diverter knob on the spigot. About 2/3rds of the time, when you pull up on the diverter, it just goes “thunk,” and nothing comes out of the shower head. It’s more likely to work when I pull the diverter knob when the water flow is still low.
I bet the home owner is extremely smart and is an engineer! Jealous of the “study!”
Instead of reducing the volume of water to the shower/tub, he could have install a shutoff valve on the shower arm before the shower head.
There's nothing stopping the homeowner from saying "Wow. Thanks for fixing it but what about X?". They have limited screen time per segment per episode, There's every possibility the final result isn't in the edit they're just showing the fix in broad strokes.
Love armchair "experts" critiquing someone doing things professionally for literal decades.
The professional goes to fix a machine, looks it over for a few minutes, then tightens one bolt. It works perfect. He sends a bill for $1,000. The client is furious! $1,000!? How do you figure, you just tightened one bolt!
The professional says: 1 Bolt: $0.50. The years of experience to know which bolt: $999.50.
That is not a solution for me. Now you have very low water pressure. What if someone wants to take a shower? Ill that even work now that there is lower then normal water pressure?
It was a cheap fix
Great fix, take it down to 0.25 gpm flow rate.
I like a good strong shower, I think I would be disappointed.
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