First, to describe my tub/shower it is a one handle, one spout type setup where you pull up on the knob to direct the water flow to the shower (typical setup).

Recently I noticed that when I go to fill my bathtub the water pressure is significantly less than it used to be and it takes much longer to fill the tub. The hot water is also not as hot as it used to be when I turn it completely to the hot side. However, the shower does not seem to lack in hot water (it feels like it gets hotter than the bathtub) and the water pressure does not seem to have changed either. Granted the shower always had excellent water pressure so I am not sure if it just went from really strong to just strong.

About a year ago I replaced the spout because the knob to direct the water to the shower wasn't working (when I moved into the house). Also, I don't think there is a leak because I have gone to the meter when I did not have any water running and it did not move.

I am not really sure where to even start here, any ideas?

2 Answers 2


Your water temperature went down. As a result, you are using much less cold water when you mix it to preferred temp. With less cold, total flow is reduced. The shower doesn't care because it was already restricted below that flow level, so nothing changes for it.

  • If I increase the temperature on my hot water heater should that help? Is that something I should be concerned about given that it has changed when I haven't touched the hot water heater? Commented Mar 2, 2017 at 22:42
  • 1
    You might check out if something is wrong with the heater, or it got bumped. A new reason to keep water heaters hot is emerging; apparently Leigonella (Legionairre's disease) can thrive in a tank water heater at temperatures less than like 135F. If it's a tankless, could it just be that the incoming water is now colder due to winter? Commented Mar 2, 2017 at 22:46
  • Thanks, I will give it a shot. I am in a warm climate so that shouldn't have anything to do with it but hopefully this does the trick. Commented Mar 2, 2017 at 22:51

Harper's answer is good. But also, do you live in a hard water area? Calcium build up in pipes and water heaters can cause the system to change A LOT. Also, your water heater should be flushed annually to remove sediment build up.

  • I do live in a hard water area and I actually ran out of salt in my water softener and have since filled it up. Now that I think about it the issue started around that time. Is there a way to clean out the calcium build up? Commented Mar 3, 2017 at 14:23
  • I doubt it would be that quick.. but who knows... anyhoos there are a few references on line for that. Maybe check this video out. youtube.com/watch?v=JiDTkXd52DE
    – Trevor_G
    Commented Mar 3, 2017 at 14:26
  • You might want to get the water softener checked too.
    – Trevor_G
    Commented Mar 3, 2017 at 14:33

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