# Showers and Toilet Flushing -- facts and etiquette? **URL:** \ **Category:** Factual Questions\ **Created:** [October 27, 2002, 8:55pm UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153 "2002-10-27T20:55:34Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![AntaresJB](https://avatars.discourse-cdn.com/v4/letter/a/c2a13f/32.png) [@AntaresJB](https://boards.straightdope.com/u/AntaresJB)\ **Post date:** [October 27, 2002, 8:55pm UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/1 "2002-10-27T20:55:34Z")
We all know you’re not supposed to flush the toilet when someone’s in the shower… but the reasons why that I have heard are different. I’ve heard that it causes a surge of hot water out of the shower that will burn the shower-er, but then I’ve also heard that the surge is cold water, thus producing discomfort that way. I myself have experienced hot water surges when a toilet is flushed (living in college dorm with 35 girls sharing 8 toilets and 8 showers, these events coincide), but never this cold surge… so which is it, hot or cold? or both, maybe depending on the plumbing system? Also, as a secondary question, which maybe should belong in a separate post in IMHO, but I’m including because it directly relates… what is the etiquette for situations such as college dorm bathrooms, where there will inevitably be showering and toilet flushing going on at the same time? Should the flusher give the showerer(s) some sort of warning? My mother told me freshman year that the policy when she was in school many many years ago at University of Maryland was that if someone was in the shower, the flusher would yell “FLUSHING!” right before doing so. But in my dorm, there is no such warning system and otherwise I’ve never heard of one, one must just be dilligent and move when one hears flushing while in the shower… any thought on this would also be appreciated. A very clean person with a potty-mouth… ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [October 27, 2002, 8:58pm UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/2 "2002-10-27T20:58:59Z")
It will give a surge of hot water as the cold water is redirected to the toilet. (The only time you will have a surge of cold water is when you’re running a dishwasher or washing machine. It won’t be a surge per se, but the hot water heater will run out of hot water and the water will become colder.) As far as in a dorm, I wouldn’t worry about it. ---
**Author:** ![kniz](https://avatars.discourse-cdn.com/v4/letter/k/c37758/32.png) [@kniz](https://boards.straightdope.com/u/kniz)\ **Post date:** [October 27, 2002, 10:57pm UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/3 "2002-10-27T22:57:47Z")
Flush the toilet and cold water is required thus taking cold water away from the shower. Since the person is in pain during this procedure, it is no wonder that most do not also notice that the water pressure decreases, instead of surging. ---
**Author:** ![Walloon](https://avatars.discourse-cdn.com/v4/letter/w/fbc32d/32.png) [@Walloon](https://boards.straightdope.com/u/Walloon)\ **Post date:** [October 27, 2002, 11:40pm UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/4 "2002-10-27T23:40:32Z")
Some plumbing systems are designed to avoid this cold-water diversion problem. ---
**Author:** ![FisherQueen](https://avatars.discourse-cdn.com/v4/letter/f/58f4c7/32.png) [@FisherQueen](https://boards.straightdope.com/u/FisherQueen)\ **Post date:** [October 27, 2002, 11:47pm UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/5 "2002-10-27T23:47:21Z")
When I was in the dorm, I experienced this regularly, but it was always preceded by a slight but noticeable loss of water pressure before the water became scalding-hot. By the time we made it through freshman year, we had learned to jump out of the water when we felt that loss of pressure. By senior year, we weren’t even thinking about it. I was amused to discover (five or six years after leaving the dorm) that, when I stayed in a college dorm for an academic conference, I instinctively jumped away from the water as soon as I felt the pressure dip. Apparently, I am completely conditioned now. ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [October 28, 2002, 12:43am UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/6 "2002-10-28T00:43:42Z")
It’s not the flush, it’s the tank refilling that takes the cold water away. Depending on how long it takes for your tank to refill, the reaction varies. A slow trickle would be barely noticeable in the shower, but a faster fill would - but it’d be brief. As for etiquette - depending on how long the other is in the shower for, maybe one should wait. ---
**Author:** ![Guinastasia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guinastasia/32/5751_2.png) [@Guinastasia](https://boards.straightdope.com/u/Guinastasia)\ **Post date:** [October 28, 2002, 1:37am UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/7 "2002-10-28T01:37:38Z")
I’ve also noticed that if I flush the toilet before I start to take a shower, I have to wait until the toilet stops running, otherwise I can’t adjust the water right. ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [October 28, 2002, 2:45am UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/8 "2002-10-28T02:45:34Z")
I love living in an apartment where NONE of the water is connected 🙂 And I think we live on a floor with a pump, too, because we have AMAZING water pressure, and pretty much can always get really hot water when we want it. And the best part? The cost of water is included in our rent, so we can take nice long showers and not get bothered with getting burned or runnibg out of hot water 🙂 ---
**Author:** ![Aspidistra](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspidistra/32/3894_2.png) [@Aspidistra](https://boards.straightdope.com/u/Aspidistra)\ **Post date:** [October 28, 2002, 3:37am UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/9 "2002-10-28T03:37:08Z")
**Antares** : When _you’re_ the one in the shower, can you tell if other people are flushing? Do you get a rush of boiling water? If not, don’t worry about it. ---
**Author:** ![Church\_Key\_Kid](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@Church\_Key\_Kid](https://boards.straightdope.com/u/Church_Key_Kid)\ **Post date:** [October 28, 2002, 6:52pm UTC](https://boards.straightdope.com/t/showers-and-toilet-flushing-facts-and-etiquette/134153/10 "2002-10-28T18:52:54Z")
As for dorm etiquette… instead of yelling “Flushing!”, you should yell, “Fire in the hole!!”