In his book “Eight Weeks to Optimum Health”, Dr. Andrew Weil warns readers against drinking or cooking with tap water, particularly hot tap water, claiming it is “unfit for human consumption”. I don’t have the book in front of me, but the reason he gives is that there are chemical toxins in the plumbing and the water heater, and these get into the water, especially once the water is heated. Is there any factual basis to these claims? Although I often hear claims that bottled or filtered water are of better quality than water straight from the tap, the phrase “unfit for human consumption” seems a bit hyperbolic. Do thousands die every year from hot tap water? If hot tap water is unfit to cook with, is it safe to eat off of dishes that have been cleaned with hot tap water? Is a hot shower or bath dangerous?
All good cooks will tell you never use hot tap water in a recipe that calls for hot water. Instead heat the water on the stove and then add it to your recipe. I doubt that anyone would die from consuming hot tap water. But all you need to do is look at the insides of an old water heater and that would be enough to convince you not to cook with the stuff. Doing dishes and showers are safe enough. IMHO.
I always use piping hot water from the faucet to prepare my tea and, as I post this, I am still alive. I don’t know how long I’ll last though.
There was a time, when there was lead plumbing, when avoiding hot water from the faucet might make sense but today I doubt it makes any difference.
But what you see is stuff the heater took out of the water, not put into it.
Peace,
mangeorge
Yuch, c’mon sailor, brew up some fresh tea! Whether there is lead in your plumbing or not, (good chance there is, lead in solder was only outlawed in 1986) the hot water system contain metallic parts that corrode over time and contaminate the hot water. Also, back to lead, hot water picks up more lead than cold water does.
This has been done.
[sub]You have no idea how much trouble I had finding that thread, because two of main search terms, tap and hot, are under the search term length limit, grrrr[/sub]
I would drink hot water freshly heated over cold water that’s been sitting the pipes overnight. It’s time and heat that affects leaching. It would only be bad if it was sitting a long time, but the same is true with cold water. And since hot water in metal pipes quickly turns cold, we’re talking about an almost unmeasurable difference.
And as the previous thread indicates, some people just don’t understand the concept of “crap settles out of water in the heater tank and makes it cleaner”.
For some strange reason many people have the idea that the tap water in their area is an exception to the above and that the bottled water they drink is equally an exception. 
Ha! You should see what it goes through in the municipal water system. That’s where it picks up all that crap, which in the case of cold water, it never has a chance to settle out in the heater.
It would be interesting to take samples from both hot and cold, and test them for differences. Any volunteers?
I’d like to try and get some water samples analyzed at my school; it has a very good chemistry program and trains analytical chemists. If I can get them to test some samples for free, I’ll do it.
Assuming I can, any requests as to what to look for?
- alkalinity/hardness differences between hot & cold
- dissolved gasses (that might be tricky)
- metals from pipes, oxidation, and solders
- any other requests?
I want to request that you take samples at different times of the day. The first time you turn the faucet in the morning, you get water which has been sitting in the pipe for hours. It may be very different from the water you get just after everyone has taken a shower.
Plus, have you considered all the chemicals that leach out of the plastic bottles and into the water you drink? Does it disturb anyone else that bottled water has an expiration date, usually 6-12 months? How do you know that a bottle of water that is simply reported as having been “bottled at a municipal source” is any better quality than you get out of your own tap?
Just a few thoughts…
The primary difference between “cold” (i.e. room temperature) tap water and “hot” tap water is that the hot stuff is hotter than the cold stuff. And the cold stuff delivers whatever nasties there may be in your pipes just about as fast as the hot stuff does.
As for lead, if your pipes are old, there may be some in the joints. But consider that lead’s melting point is roughly 620 deg. F. I don’t know about y’all, but my hot water is delivered to me at a temperature considerably lower than that.
We have children in this house, and I shudder to think of the bucks that are spent on bottled freaking water.
Lead in pipes is indeed an issue to be concerned about, whether cold or hot water. Enough lead can leach into the water to affect children, even below the melting point of lead. If you have a home built before 1980, and have children, you should test for lead in the water.
I wouldn’t worry about any other metals in your tap water, again cold or hot. (see story below)
The only reason to avoid drinking hot water that I know of is that there is a remote possibility that a hot water heater could turn into an incubator for bacterial nasties. I’ve got better things to worry about, myself. At any rate, if you’re going to boil it, any bacteria are going to be killed anyway.
And yes, bottled water is less strictly monitored than tap water (which could be the original source of a lot of bottled water anyway).
** Metals in tap water story: A friend of mine for a graduate project tested a bunch of water samples for trace metals, using the school’s fancy equipment. He got samples from a bunch of municipalities in the NorthEast US, I believe a couple of bottled water samples, and a couple sent through a Britta filter. The only thing he found at anything above trace amounts was in the samples filtered through the Britta, which contained silver. (The filter in the Britta and many other filters contains silver to keep bacteria from growing on the filter).
Heath Canada advises that you run your cold water tap for five minuets every morning in order to flush out all of the heavy metals & “stuff” that has leeched into the standing water over night. When you consider all of gunk that has settled out into your water heater, you have to wonder how much of that stuff has leached back into the water. Water sits longer in the heater, because it is used less often than cold water, so it has quite a bit of time to brew a nice batch of gross stuff. Also, the heat in the water heater (and a short distance down the line) can be a terrific place for a myriad of microbial life forms to spawn and prosper.
Mmmm… microbes…
-Coffeeguy
Five minutes? At a gallon a minute, that’d be long enough to clear 316 feet of 1/2" tubing. At that point, i’d be trying to clear the municipal supply. I wonder what my actual flow rate is…
Hey man, I’m just quoting the T.V. PSA. Maybe it’s that long to help clear the depleted uranium.
-Coffeeguy
If I’m picking on anyone here, Coffeeguy, it’s Health Canada, not you.
The other downside to botled water is that you pay money. Instead of paying that money (and wasting the environment with the gas and plastic it takes to make and haul those bottles) just get some filters on your tap, and/or a filtered pitcher. How would that be? Or are filters all a bunch of baloney?
Well I talked to the prof today, and he explained things well enough that an actual test wouldn’t even be neccesary to answer the question of “will hot water from the heater tank pose a threat to my health vs cold water?”… so sorry, no test results.
If your water has any alkalinity at all, you’ll be more interested in learning the solubility of the metal carbonate salts rather than the metal it’s self since that’s how the metals will go into solution. Even so, with water 60C warmer sitting in your pipes, you might double or triple the metal’s solubility in the water. The next thing you’d want to know is do you have lead pipes? Where I live they don’t exist anymore, and even copper is on it’s way out. If you do have lead pipes you shouldn’t really be drinking any water flowing through them; worrying about how much more lead gets into the hot water from the tiney amount of contact time and length of unsuitable piping is sort of like worrying about whether you smoke light vs regular cigarettes - you’re screwed either way.
The amounts of dangerous metals in proper piping are only present in trace amounts anyways, which shouldn’t be dangerous… there’s more potential for your water supply to have bad water at the source (which is regulated) than for it to become dangerously contaminated flowing through 15 feet of pipe for a few seconds.
And once again the scale you see in water tanks (mostly from calcium bicarbonate) has been precipitated out of your water during heating, hence this water has less of these minerals in it when it comes out the tap. And the reason it precipitates out is that the water cannot hold more than a certain amount of these minerals at the temperature it gets heated too, so it’s not gonna pick up any extra when it flows through the heater tank. If your water is depositing minerals already, it’s not going to pick up any more even if you dumped 50 pounds of it into the tank. Not to mention that calcium/magnesium carbonates and bicarbonates aren’t going to hurt you anyways.
For that matter, neither will copper or iron in the amounts leached into a few feet of pipe - people purposely take all kinds of metal supplements daily. And to be picky, there will be one hell of a lot more metals leaching out of your pot or pan once you start frying or boiling at the really high temperatures than will come out of your water pipes at relatively low temperatures… and then we go scrubbing those metal pots nice and good afterwords to expose more new metal for the water to suck out next time, leave a bit of soap residue on them, and so on…
Lastly I measured the flow rate of my kitchen sink and the length of pipe between it and the water heater. There are about 15 feet of 1/2" copper pipe between the two, which holds a volume of 0.6L. The flow rate is 12L/minute. I also timed how long it took for the water coming out of the hot tap to “get hot” - 15 seconds.
So, at a flow of 12LPM, it takes 3.2 seconds for the entire volume of the heater-to-sink hot water pipe to clear, and by the time the water is hot enough for me to stick the pot underneath it, that volume has been replaced almost five times. The water going into my pot has a total exposure time of 5 seconds at 60-70C in those copper pipes. The metals that would have leached into it overnight are long gone before I even grab a pot to fill.
Disolved gases like chlorine will come out of solution faster from heated water, which most would consider good; even so the chlorine concentration is too low to be dangerous. Most of the bacteria that are human pathogens are mesophilic, dying off at temps above 45C… the thermophilic bacteria that may be in your water heater, if not already dead from the cold initial temps and chlorine throughout their stay, don’t seem to be a problem either.
The guy I talked to has been a water chemist for the past 40 years, and a bit of an alarmist at that… anything even remotely dangerous he goes on and on about. When I asked him about this, he didn’t even bat an eyelash and admits that he uses hot tap water to boil things faster himself. Ok, I think I’ve rambled on enough for now 