Which method will give me ice water faster?

My guess is fill with ice first. That is how I would do it. I think you will fit the maximum amount of ice that way. Did you test it?

About 95% of the time I do ice first, then water. Ten minutes ago (I was at the sink) I did water first, then ice.

My non-scientific impression is that water first was slower.

But… it’s really hot here and I was really thirsty.

I would guess that the ice first method would be faster, since more of the water will have direct contact with the ice when you fill it up.
In any case, just give it a stir afterwards.

I would do both at the same time.

Ice first.

I don’t think it makes any difference. It’s the same amount of ice and the same amount of water in the same amount of time.

I think ice first allows the water poured over it to cool down as it passes each piece of ice.

@kritiper We would have to fill a glass with ice and then measure how much water will fit. Then try it with that much water and adding the ice afterwards. Without doing that I don’t think we can guess the ice and water amounts accurately.

@Dutchess_III I agree. Water first and then the ice you would have to stir the water to get it to cool down quickly.

1. Whichever one you can do faster, as “ice water” is water with ice in it. Dropping ice into water is harder to do quickly without making a mess, than pouring water into ice. So your glass will be ready faster if you put ice in first and then pour in water.

2. But if by “give me ice water” you mean, which method will cool the water faster, I can think of two considerations.

One is that most glasses are tapered, and most people measure ½ glass by the middle distance on a glass, so the top half of the glass has more volume than the bottom half of the glass. So if a typical person thinks they are filling a glass half with ice first, they may tend to end up with less ice in the water, than if they fill the glass with water first, so ice second would mean more ice, meaning the water would cool faster.

The other consideration is that the sooner you add the ice, the sooner the ice will start cooling the glass, which will also cool the water. This is a much less important consideration than the amount of ice, but if someone carefully made sure they were using the same amount of ice and water in each case, then the glass half-filled first with ice would start to cool down sooner than the glass half-filled first with water, so in that case, adding ice first would give you ice water sooner.

I think @Dutchess_III may also be onto something that water flowing through ice may transfer a lot of heat, compared to ice dropped into water, but I’m not sure about that.

@JLeslie The warmer water will melt the same amount of ice either way, and BTUs are BTUs. Based on @elbanditoroso question, to be precise, I assumed the same amount of water and ice would be used in both instances.

@kritiper He said he would just fill the mug halfway with water if he did water first. Who knows if it’s the same amount as ice first.

@JLeslie If he really wanted to know the answer to his question, he would have to use the same amounts in both instances otherwise he could never know the correct answer. If what you say was true, he could never get an answer, and I must assume he is intelligent enough to know that, so then there would be no point in his asking the question.

@kritiper Sounds good.

Ice first & the smaller the cubes, the faster and colder the water will be. If you fill a glass or jug with shaved or crushed ice, the water will be within 2 degrees f of the ice before you can raise the container to your lips or insert a straw.

Keeping a mug half-filled with ice in the freezer, and then adding water is faster.

I don’t see what difference it makes.

Since the rate of heat transfer is the same either way, there is no difference, assuming the same water and the same ice. However, if you want Ice Water more quickly, crush the ice (or half the ice) before adding it to the glass. The difference here is the surface area for heat transfer would greatly increase.

@seawulf575 excellent point. My fridge has a setting for crushed ice. I will try that later today.

Well, stick the mug in the freezer for 30 minutes first.

You can test it. Do you have an instant-read thermometer for cooking? If not, and if you are curious enough, one can be had for less than $10 US.

Ice first

I think you want to trigger the most entropy as soon as possible. Ice first, then pour the water over the ice. The temperature change will begin while you are filling the ice-filled jug. If you want to create an experiment for this, use the same size/amount of ice and same temperature of tap water, using both methods. The method where the ice is totally melted first is the fastest. The end resulting temperature might also be of interest. I think I want to try this now.