# Brewing coffee: why cold water? **URL:** \ **Category:** Cafe Society\ **Tags:** coffee\ **Created:** [March 3, 2024, 12:08pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391 "2024-03-03T12:08:23Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Dorjan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dorjan/32/12440_2.png) [@Dorjan](https://boards.straightdope.com/u/Dorjan)\ **Post date:** [March 4, 2024, 6:58pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/21 "2024-03-04T18:58:39Z")
> [@kaylasdad99](#): > > That sentence must have alarmed you so much that you had to respond right away without even reading the next one It did LOL. ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [March 4, 2024, 7:08pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/22 "2024-03-04T19:08:07Z")
I wonder if specifying cold water makes the coffee more uniform. If you always start with water the same temperature, you remove a big variable. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [March 4, 2024, 7:15pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/23 "2024-03-04T19:15:05Z")
> [@Hypno-Toad](#): > > I wonder if specifying cold water makes the coffee more uniform. If you always start with water the same temperature, you remove a big variable. ⁢ In my experience, “cold” water from the tap can be anywhere from nearly freezing to almost room temperature, depending on conditions and how much of the pipe is buried. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [March 4, 2024, 9:21pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/24 "2024-03-04T21:21:49Z")
I didn’t do any sort of deep dive on this one, but … Many (most?) tank-type water heaters have an **[anode rod](https://www.angi.com/articles/what-does-water-heater-anode-rod-do.htm)** built in. The anode rod’s job is to take one for the team – to dissolve into the water over time so that the tank itself doesn’t corrode first. But anode rods are generally: > a steel wire with aluminum, aluminum/zinc alloy, or magnesium wrapped around it. There are **[concerns](https://www.doityourself.com/stry/drawbacks-of-using-an-aluminum-water-heater-anode-rod)** – I haven’t looked into how well supported those concerns are – about ingestion of aluminum over time: > Some plumbers say that aluminum anode rods are not safe because they put aluminum in your water supply. There are some clinical studies that suggest that aluminum might be a contributing factor in Alzheimer’s disease. It should be noted that most of these studies focused on the aluminum added by water treatment plants. Which would be just one more reason not to use hot water for drinking or cooking. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [March 5, 2024, 12:57pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/25 "2024-03-05T12:57:31Z")
During the work week, my gf sips hot water all day from a carafe she fills in the morning. She boils (or nearly so) cold tap water for this. She could more easily fill her carafe directly from the hot tap, but it tastes off to her. ---
**Author:** ![bobsmom101](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bobsmom101/32/2867_2.png) [@bobsmom101](https://boards.straightdope.com/u/bobsmom101)\ **Post date:** [March 5, 2024, 3:52pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/26 "2024-03-05T15:52:07Z")
I have a percolator and @TriPolar is correct. You need the water to circulate through the grounds enough times to extract the coffee flavor before the thermostat gets to shut off temperature. If you start with hot water you will get weak coffee. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [March 5, 2024, 6:41pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/27 "2024-03-05T18:41:15Z")
That suggests that water from the tap can be hot enough to start circulating through the grounds right away. Surely there’s a minimum temperature it needs to reach before it can _begin_ getting up the stem, and using hot tap water can only shorten the time it takes to reach it. Or are you only referring to water that’s been added from a boiling kettle? Anybody dumb enough to operate their percolator that way probably _deserves_ weak coffee. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [March 5, 2024, 9:21pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/28 "2024-03-05T21:21:52Z")
> [@kaylasdad99](#): > > Surely there’s a minimum temperature it needs to reach before it can _begin_ getting up the stem, and using hot tap water can only shorten the time it takes to reach it. Yes. And it will also shorten the time it takes to get up to the shut off temperature. It takes fewer perks to get up to that temperature, and that means less water goes up the tube and through the grounds. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [March 5, 2024, 9:29pm UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/29 "2024-03-05T21:29:18Z")
Sorry, I HAVE to believe that _PERCOLATE START MINIMUM TEMP_ to _SHUTOFF TEMP_ time is a constant. That is, I believe that there are ZERO perks happening before the water reaches a minimum temperature (which, ideally is above the maximum for tap water). ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [March 6, 2024, 12:11am UTC](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391/30 "2024-03-06T00:11:27Z")
A percolator heats a small volume of water at the bottom under the tube. That small volume will come to perking temperature way before the whole pot gets to that point. The whole pot gets hot over time as a result of a lot of small perks. [Previous page](https://boards.straightdope.com/t/brewing-coffee-why-cold-water/998391.md?page=1)