I seem to remember reading in the NY Times recently that hot water from the tap had more lead in it, as the heat released the lead from the pipes. Meaning, I think, that to be safe from lead that one should heat cold water from the tap and then use it to make ice cubes.

Of course, this might only be a problem for people who use a lot of ice.

Reply

It's not really the heat that makes less air, but the fact that hot water has been resting in your hot water heater, whereas the cold water is coming pretty directly from the public water source (and therefore more turbulent and more aerated). I've heard this is why cold tap water makes better tea, more air in the water helps the taste.

Reply

I've heard that drinking hot water from the tap is really bad as a lot of germs and bacterias develop in the tank... If you want clear ice cubes, use cold water, boil it, let it cool (I think, boil it again), and then let it cool and put it in the freeze... it's a lot of work for transparency, but at least you will not be freezing bacterias who will later take a plunge in your drink !

Reply

always use cold water from the tap (hot water has some nasty stuff in it: lead, tons of bacteria, etc.)

for super clear ice cubes, you need to take cold water, boil it, let it cool, and boil it a second time.

but really? i think you're fine with ice cubes that are a little cloudy

Reply

@Kearns: Actually, the heat helps. The solubility of gases in liquids decreases as the temperature rises. That's why Ariel's suggestion of boiling and reboiling works. I've done it once or twice myself, but as she says: I'm fine with ice cubes that are a little cloudy.

Reply

Cold water can hold more air in it than hot water can, and this is the "science" that Bob's talking about.
One question I DO have is why the hot water would have bacteria in it? If the water supply is clean (because it is chlorinated from the municipal water supply, and/or the temperature is set above 140 degrees F, etc.) to begin with, how is it getting all this bacteria in it? For safety, one can add thermostatic mixing valves to prevent scalding hot water coming out of the tank...

Reply

I've actually done a bunch of experiments on how to make clear ice. I haven't totally succeeded, but I'll tell you what I've tried:

I know this much: the cloudy bits in ice consist of two things:
1) dissolved gasses that precipitate into tiny bubbles as the water freezes. Gasses are less soluble in hot water; that's why warm soda goes flat, FYI. Gas solubility in water also drops as pressure drops.
2) minerals in the water, which also get pushed out as the water freezes, forming tiny mineral precipitates.

So I did this: I heated distilled water (which I bought in a jug at the market) to a boil, and then I put it into a bottle, and used one of those vacuum wine preservers to suck all the air out. The ice was much more clear, but there was still a bit of cloudiness at the bottom, which I suspect came from the minerals left on the pot from washing in regular water. The hot distilled water probably dissolved them, leaving the water less than perfectly pure.

I will try this experiment again sometime soon.

Reply

BTW, there's a video floating around on all the video sharing sites that claims that filtered water boiled, cooled, and re-boiled will freeze clear. The video even includes a demo ice cube to prove the technique. I have not tried double-boiling filtered or distilled water yet, but for your information, that's the other technique out there. Boiling your own water means you won't risk dissolved lead and stuff like that, presuming that you don't use leaded cooking pots.

See this: http://lifehacker.com/software/video-demonstration/make-clear-ice-313194.php

Reply

I also heard that cubes made with hot or warm water freeze faster than with cold water. I've tested the theory. It's true.

Reply

just do it the easy way....

go to your nearest 7-11 and buy a bag of ice

Reply

The other factor is having the ice freeze from only one side. Insulate the other sides of the container. As the ice crystal forms, it forces air and other impurities into the liquid water ahead if it. You will notice that the air bubbles in an ordinary ice cube are in the center, which is the last to freeze.

Reply

bottled water.. idk why but that always makes the clearest ice cubes and you dont have to be heating and re-heating

Reply

It's alot cheaper to just buy bag ice, which is clear and save all that time boiling and reboiling, don't you think? Of course, if you want to have clear ice cubes in a special shape, or you just want to see if it works, it is a good idea.

Reply

NEVER USE tap water for ice cubes. The Municipal (City) Water had high concentrations of Chlorine and other chemicals to kill bacteria. Actually, with the levels of Chlorine in you water..you're actually freezing BLEACH! If you wouldn't shower in your Pool water or drink your pool water why would you DRINK or shower in your Tap water? Put SHOWER Filters on your shower...install a water filter by your sink! Chlorine has been linked to all kinds of health issues and people with skin problems. Chlorine (tap) water dilutes the effectiveness of soap/shampoo when you take a shower....when turn on the HOT water your shower produces Chlorine Gas because of the steam. Put a filter on it! Lord knows when you take a bath how much chlorine your skin is absorbing! Trust me!

Reply

Want really clear ice? I would suggest a small ice maker which makes ice by freezing it upside down. There is a metal tray which is refrigerated and has water sprayed up into the form. The ice forms and excess water - AND MINERALS - do not become part of your crystal clear ice cubes. This is how bars and good restaurants get perfect ice cubes.

Reply

Where, oh where, do you folks get this stuff? Lead in hot water? Lead solder, much less lead PIPE, has been outlawed for decades. Hot water has more bacteria? Astounding! Chorine? The jump is made from 'pool water' to 'drinking bleach'. Are you all aware that a common potato has 200 toxic compounds in it? EVERYTHING will kill you!! Gee, take a science class or two, please!!

Reply

If ya put enough Vodka over em , WHO CARES?

Reply

On most sinks there is an aerator which introduces a lot of bubbles.

There used to be a company that sold "Square" ice cubes sawn from big blocks. (I'm sure they meant "cubic")

Reply

The safest thing to do is have a water treatment system installed. It will purify your ice and clean your water throughout your whole house! Someone commented about the chlorine affecting you when you take a shower, he's right your exposure to chloroform gas is greater when showering up to 600% greater than what you get by drinking the water! You absorb about to 2 liters of water through your skin when showering. So just drinking bottled water or filtering you tap water doesnt really help. Your still being exposed! My husband and i bought a Rainsoft water treatment system, we live in northern virginia and there is always problems here with tap water and i just got tired of the bottled water routine, this is so much better. you can see what im talking about at Rainsoft.com I hope this helps.

Reply

As a water/wastewater civil engineer, I must say you people are insane. There are many regulations about how much residual Chlorine can remain in municpal water systems after treatment. This is monitored using a SCADA system or some other sort of post-treatment monitoring device. This is not Mexico. It IS safe to drink the water! In fact, many water departments add Fluoride (in SAFE, monitored quantities) to your water to help protect and strengthen your teeth, so drinking tap water (unless it comes from a personal well, which is altogether separate) is actually GOOD for you!

Reply