Where does my coffee go?

Factual Questions
1

My drip coffee maker has started making my coffee disappear.

I pour in 12 “cups” (using the bogus coffee definition of a “cup”) of water each night, add ground coffee to the cone-shaped filter. In the morning I get back about 8 cups of coffee.

I ran an experiment last night, and used the same amount of water (and a filter) but no coffee, and got 11.5 cups of hot water. So apparently the coffee grounds are absorbing the water, not surprisingly. But the missing water weighs about 1 lb, and my filter of coffee grounds weighs an ounce or 2, max.

So where’s my coffee?

2

Do you have the pre-charged type where thier is always a full tank of hot water? If this is the case I would think a seal is bad somewhere allowing for vapors to escape instead of condensing and running back into the tank.

3

I’m not sure, but it could be steam, which coffee makers emit usually when it is finishing making the coffee.

4

gallon of water = 8.33 lbs
16 cups in a gallon
a coffee cup “cup” is really about 1/2 cup on my coffeemaker

So you lost 1/2 of a coffee cup, so you did not lose a pound of water! Maybe 1/8 of a pound. I bet the grounds absorbed that much, and some evaporated as steam too.

5

actually measure the weight of the substances. report back.

6

Coffee gives you energy. The missing mass has been converted to energy.

7

Steam and grounds absorption are the usual places. Most makers completely empty the tank, but may boil off the last few ounces ineffectually. (Side-tank types use the boiling steam pressure to push the hot water up and through the mechanism; at a certain point this fails and the last bit of water just boils away.)

I fill mine to the very brim of the water tank, probably a cup past the 10 mark, to get a full carafe.

8

In addition, the OP is setting up the coffee maker the night before (it is dark). In the morning it is light, and that light needs energy for its creation. All told, he’s lucky to get any coffee.

9

If you come upon a hallucinating rat twitching it’s way across the counter, you have your answer.

10

Also, coffee is a diuretic, so it causes the pot to lose fluid at a high rate.

11

I lost 4 “cups” when there’s coffee in the filter. The 1/2 cup loss was my experiment with no coffee.

4 coffee “cups” = 2 real cups = 1 pt = 1 lb (“a pint’s a pound the whole world 'round”)

12

[del]A cup of coffee officially is 6 oz. That’s probably what the coffeemaker is measuring it as.[/del]

As soon as I posted this, I found other equally reliable sources claiming 5 oz. as the standard.

13

Interesting…I wonder if mine is failing prematurely, and excess boiling is happening?

14

You shouldn’t lose water unless the pot is preheating the water over night.

We have that problem with our commercial Bunn coffee maker at work. Every Monday some of the hot water in the reservoir has boiled off over the weekend. We always run a pitcher of water through first before trying to make coffee. Otherwise you only get a half pot of coffee for a pitcher of water.

15

We have a coffee maker with a built-in grinder. We lose no more than half a cup or so. The tank and the pot both have markings - and there is no fudge factor since if you fill the pot to 12 cups and put it in the tank you get 12 cups of water in the tank.

Perhaps pre-ground coffee absorbs more? We’ve also had leaks or runovers during brewing - look under the coffee maker for puddles.

Do you still get a loss if you fill it and brew immediately?

16

Poltergeists are notorious coffee addicts. That’s how they stay up at night to pull pranks.

17

You know that it’s not, do you? 1 imperial pint equals 20 fl oz = 19.98 oz (approx), so a pint’s a pound in the US only!

18

Mystery (largely) solved. Last night I filled the reservoir with 12 “cups” of water. And for good measure, I weighed the filter and ground coffee: 1.2 oz.

This morning, I peeked into the reservoir before it started dripping, and was surprised to see that the water level had dropped below the 10 cup mark.

So it’s evaporating overnight. Why it’s started to do this recently, I do not know – change in humidity maybe?

And just for completeness, the weight of the used coffee grounds + filter was 3.2 oz.

19

That seems like a lot of evaporation to me. Isn’t there a cover over the water? Even without a cover, that still seems like a lot. Is the water heated all night? Are you sure there isn’t a puddle under the coffee maker?

20

Yes.
No.
Yes.