If I need to boil a giant pot of water, which is the less wasteful way?

Question

a) Turn on the hot water and let the water run until it is hot (which results in a lot of water going down the drain)?

b) Filling the pot with cool water (thus not wasting any), but it will have a longer heating time and use up more energy?

Answer 1

All that hot water in the pipes between the boiler and the sink will cool off, wasting much more energy than boiling cold water. The boiler will turn on to heat the water in the tank back up to operating temperature, using more energy.

Plus, hot water will have higher levels of contaminants like lead leeched from the pipe joints.

Boiling cold water is better for many reasons.

Answer 2

There is not much difference in the two choices based on the info provided. For (a) you need to heat the water somewhere (presumably the water heater) before it comes out of the tap.
For (b) you heat the water on the stove instead of the water heater.

The answer depend son how your hotwater heater and stove operate. Does the stove use gas or electric, is the hotwater heater gas or electric? If both are gas or electric, they will each use exactly the same amount of energy to heat equivalent amounts of water. However, heating cold water and using the stove is likely the best because you are heating a smaller volume of water (a pot full vs. a hot water heater full). With the water heater, you have to let the water run and run from the tap until its gets hot enough, which means you empty more hot water from the water heater, and the water heater has to work that much harder to reheat all the new cold water that comes into it.

Answer 3

When boiling water you should always use cold water out of the tap. The hot water has had time to lay stagnant in the pipes and will absorb significantly more minerals from the pipes than cold water.

That being said, I really don't know which is more wasteful. I guess it depends on how much water, how hard your water is, how efficient you water heater is, etc...

But the difference is going to be small compared to other habits we have. If your that concerned about being wasteful, then the next time you shower. Turn the water off while you lather up. I guarantee that amount of water and energy you save will more than offset any waste you create by using cold (or hot) water out of the tap.

Answer 4

I say the cold water in the pot. Even if you get the hot water from the tap, it still had to be heated in the water heater by burning gas there. Why not save the wasted water and just heat it on the stove. It is the same amount of heat added to the water. Unless you think the water heater is somehow more efficient, but I doubt it is, unless you have a solar hot water heater.

Answer 5

That's an interesting question.

The problem is you're comparing apples to oranges. In one case you're using more water, in another you're using more energy. So you can't compare the amounts that you're wasting.

However, it takes energy to heat up the water in your water heater. So not only are you wasting water by letting the fawcet run, but you're still using energy to heat up the water (though your water heater is more efficient than your stove).

So overall I'd say it's less wasteful to heat up the cold water on the stovetop - option B. Put some salt in it to lower the boiling point and cover the pot to retain heat, too.

Answer 6

The amount of energy required to heat the water to a certain temperature, regardless of which method you choose, is the same, however the methods (partially heating via your faucet or on a stove top) may vary in their efficiency. One method of heating may be less efficient therefore resulting in wasted energy. Of course in method A you will also be wasting water. There is a tradeoff between water consumption vs. efficiency that complicates the question.

Answer 7

Heating cool water is less wasteful, but remember that water vapor is the most significant greenhouse gas, accounting for the majority of global warming, so environmentalists might consider you to be vandalizing the earth by boiling your giant pot of water. However, global warming reduces the amount of additional heat needed to make the water boil, so global warming should make both ways of boiling a giant pot of water less wasteful.

Answer 8

Let the water run until it's hot, because it is water that's already been heated. If you want to be eco-savvy, save the "extra" water and wait until it's cooled to room temperature, then use it to water your plants.

The best tip for boiling a giant pot of water, though, is to put a lid on the pot and it will come to a boil twice as quickly than it would had you not used a lid.

Answer 9

I would drop a 1" cube of sodium in the pot of water. This will heat up the water and produce hydrogen! It will not result in a greenhouse gas.

Answer 10

I tend to mix this operation with filling the sink for washin up, thereby making it an even more complicated calculation.

Perhaps you could use the water from the tap while you're waiting for it to run hot for other uses; plants, soaking beans, drinking, filling the kettle..