# Why does water in a faucet change pitch as it heats up? **URL:** \ **Category:** Factual Questions\ **Created:** [February 8, 2022, 1:28am UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076 "2022-02-08T01:28:54Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Nars\_Glinley](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nars_glinley/32/8177_2.png) [@Nars\_Glinley](https://boards.straightdope.com/u/Nars_Glinley)\ **Post date:** [February 8, 2022, 1:28am UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/1 "2022-02-08T01:28:54Z")
I’ve noticed that in my bathroom sink, the pitch goes down as the water transitions from cold to hot. Why does it do that? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [February 8, 2022, 2:54am UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/2 "2022-02-08T02:54:11Z")
The washer that seals faucet the flow heats up and expands slightly, narrowing the opening and rising the pitch. You will note that this almost never happens when the water is running fast - only when the faucet is mostly closed, and the change in size of the washer makes a significant difference. ---
**Author:** ![Nars\_Glinley](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nars_glinley/32/8177_2.png) [@Nars\_Glinley](https://boards.straightdope.com/u/Nars_Glinley)\ **Post date:** [February 8, 2022, 3:01am UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/3 "2022-02-08T03:01:34Z")
Actually, I’m my bathroom, it’s when the faucet is opened all the way. I do this because the water heater is in the exact opposite side of the house and otherwise it would take too long to wash my hands with hot water. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [February 8, 2022, 2:40pm UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/4 "2022-02-08T14:40:09Z")
How old is the house? I wouldn’t be surprised if your pipes are full of scale. ---
**Author:** ![Nars\_Glinley](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nars_glinley/32/8177_2.png) [@Nars\_Glinley](https://boards.straightdope.com/u/Nars_Glinley)\ **Post date:** [February 8, 2022, 4:54pm UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/5 "2022-02-08T16:54:39Z")
It’s about 10 years old. Our water is hard but I added a softener when we bought the house 2 years ago. The pipes are PEX which are _supposed to be_ scale resistant. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [February 8, 2022, 5:35pm UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/6 "2022-02-08T17:35:52Z")
I guess your faucet / pipe / water flow combination is just right to cause it to resonate, even at full flow. I would bet that changing the faucet would make the problem go away. Have you cleaned out the aerator filter lately? ---
**Author:** ![Nars\_Glinley](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nars_glinley/32/8177_2.png) [@Nars\_Glinley](https://boards.straightdope.com/u/Nars_Glinley)\ **Post date:** [February 8, 2022, 5:47pm UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/7 "2022-02-08T17:47:33Z")
I’m sorry. I didn’t mean to imply that I thought there was a problem. It was just something that I’d noticed and assumed that all faucets worked that way. The flow rate on them is just fine. They don’t have aerators. ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [February 8, 2022, 10:53pm UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/8 "2022-02-08T22:53:34Z")
I only notice it when I run the bathtub. But that said, that’s the only time I have a vested interest in the temp of the water. I don’t mind washing my hands in cold water so I immediately go for it as soon as the water is on. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [February 9, 2022, 12:04am UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/9 "2022-02-09T00:04:00Z")
> [@beowulff](#): > > How old is the house? I wouldn’t be surprised if your pipes are full of scale. I would stop there and go out on a high note. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [February 9, 2022, 12:11am UTC](https://boards.straightdope.com/t/why-does-water-in-a-faucet-change-pitch-as-it-heats-up/959076/10 "2022-02-09T00:11:30Z")
Brilliant.