Plumbing and heating expert Richard Trethewey takes us on a road trip to solve a homeowner’s shower problem. When the homeowner turns on their tub spout, water 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 fills can be annoying. 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.
Tub Spout or Water Pressure Issue: How to Tell
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, the system has too much pressure.
How to Fix Tub Spout or Water Pressure Problems
If the tub spout is the issue, 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.
Richard troubleshoots how to repair a homeowner’s water pressure valve for their tub and shower.