When the phrase "boiling water" is used in cooking instructions, does it mean "water that is fit for the purpose of boiling" (similar to the use of "cooking oil") or "water that is already boiling"? Sometimes I encounter an instruction like "Place 200 ml of boiling water in a microwavable container", followed by instructions to e.g. cook the food by placing it in the microwave. So this is what makes me doubt: if I have to cook (and therefore boil) the water later in any case, maybe the "boiling water" mentioned in the first instruction has the first of these meanings?


The specific example I've encountered this time is a packet of instant noodles. There are cooking instructions for both cooking on the hob and in the microwave, both mentioning the phrase "boiling water". Here they are (emphases mine):

HOB 2-3mins. Place 200ml of boiling water in a saucepan, add the contents of the seasoning sachet. Break the noodle block into 3 or 4 pieces and place into the seasoned boiling water. Bring back to the boil then simmer over a moderate heat for 3 minutes stirring frequently. Serve immediately.

MICROWAVE 800W 4 mins/900W 3½ mins. Place 200ml of boiling water into a microwaveable container. Add the contents of the seasoning sachet. Break the noodle block into 3 or 4 pieces, add to the seasoned boiled water and cover. Cook on full power for 1 minute and 30 seconds (800 W)/1 minute 15 seconds (900 w), stir then cook on full power for another 1 minute after cooking. Serve immediately.

After re-reading, it seems clearer to me that the meaning is the second one, as the instructions say e.g. "bring back to the boil", implying that the water was already boiling.

  • In the food/kitchen context, we do have adjectival baking potatoes, and a vanishing few will be familiar with boiling fowl (older than a roasting chicken, so needs the longer cooking method). But we don't distinguish water intended to be boiled from, for example, water to be used for washing. Commented May 26, 2021 at 14:40
  • I have never seen any directions like that, and they seem unusual for instant noodles. Usually, if you need to boil water, that is included as a separate step. And the whole point of cooking instant noodles in the microwave is that the microwave boils the water. Personally, I would just try it without boiling the water first, and increase the microwave time if the noodles are not done. Or I would just cook it on the stove to begin with.
    – trlkly
    Commented May 26, 2021 at 23:57
  • @trlkly - this may be a 240v thing*, but it is far far quicker to boil the kettle than boil it in the mic or on the stove. That first step will shave perhaps 2 or 3 minutes off the total time. You can do it even as you're prepping the noodle pot/dish/pan. *I've never tried it, but I've heard that it is considerably slower on 110v & is one reason electric kettles never really took off in the US. Commented May 27, 2021 at 6:38
  • Out of interest, how would "water that is fit for the purpose of boiling" differ from water that is not fit for boiling? Commented May 27, 2021 at 8:13
  • 1
    Simply as a parallel construction - like "drinking water". Commented May 27, 2021 at 8:31

1 Answer 1


In the context you mention (microwaving something in water, e.g. instant oatmeal) I have usually seen two distinct options:

  1. Boil water in a kettle or on the stove, and add the boiling water to a bowl containing the product.
  2. Add the product and cold water to a microwaveable container and microwave them together.

But if the instructions really do say to put boiling water in a container and then microwave it, I would first boil the water and then put it in the microwave to cook further. Boiling water in my experience always means "water that has been heated to a boil" and not "water to be boiled" as in cooking oil.

If you are able to share a specific product or recipe that calls for placing boiling water in a microwave to be cooked further I would be interested in seeing it.

Response to your edit: The phrasing they use sounds a little strange to me. I would not expect to read "Place 200ml of boiling water in a saucepan;" instead I would expect "Bring 200ml of water to a boil in a saucepan" or similar. Perhaps they are assuming you would use an electric kettle to boil the water before pouring it into the saucepan.

  • It won't be 'boiling' by the time seasoning sachet contents have been added, and the noodle block broken into it, just very hot. Commented May 26, 2021 at 14:45
  • 2
    Boiling the water in the microwave might not be safe in some rare situations, so the instructions were probably adjusted by a lawyer to minimize the risk to the company. If superheating has occurred, a slight disturbance or movement such as picking up the cup, or pouring in a spoon full of instant coffee, may result in a violent eruption with the boiling water exploding out of the cup.
    – ColleenV
    Commented May 26, 2021 at 14:52
  • In response to the edit, quite a lot of people I know use boiling water when making pan sauces (mostly packet, tbh) to prevent the pan from cooling down. Not that it particularly matters from a cooking perspective (as far as I care), but usually your meat's getting cold so you'd want to not have the sauce take longer than it must. Not a cook, just some anecdotal cooking from amateurs.
    – Flater
    Commented May 26, 2021 at 22:55
  • 3
    @ColleenV I like that theory. It's also possible that the manufacturer has found that the seasoning powder dissolves more readily in boiling water than in cold, resulting in a better-tasting product with less grit left at the bottom. Commented May 26, 2021 at 23:28

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