I have an ongoing debate of sorts with my wife and mother in law over this topic. They insist that one should not drink water from the hot water tap because, they say, it is unhealthy. When pressed as to why they mutter something about stagnant water in domestic hot water systems.
We have a gas storage type HWS, not an instant sort.
I would have thought that there was sufficient turnover of hot water through the tank that there was no relevant danger, and that since the water is at a comparatively high temperature it would be too hot for nasties to grow anyway, and also that it being a sealed system with only clean water coming into it there is no obvious way for nasties to get into the tank anyhow.
But they insist. They are from England where I suspect water systems in general are older and of lower quality, and maybe that’s where (what I perceived to be an old wives tale) comes from.
I’ve always been told that (originally from England) and I think it’s a load of cobblers… water is constantly flowing through the hot tank and the cold tank… if you’re gonna boil water for something, why not take advantage of the already hot water and reduce the boiling time?
I suspect it may go back days when lots of places still had lead pipes… but I’m just guessing…
I wouldn’t use it for cooking or drinking on a regular basis. I have no idea how much hot water dissolves things as compared to cold. However, water does contain hydrogen and hydroxide ions that might be more active in taking up nasty things into solution when hot than when cold.
As for hot water picking up more metals than cold, I just got done a painful read from a bunch of old geochemical PHd guys who found that redistribution of some damn metal I never heard of increased by 1.24% when atmospheric pressure was doubled and the water temperature was brought up to 380C, so the amount of extra crap going into solution when your water’s at 65C is likely barely even measureable.
Even so, the water travels through miles of pipe to get to you, and it’s only in the last few feet between the hot water tank and the tap that you’d have a chance for hot water to pick up any additional contaminants, so you don’t have to worry about 99% of the piping leaching extra stuff into the hot water on top of the above.
Once in the tank there should be little if any extra rust as any decent water heater will have a bonded glass liner in the steel tank to keep it from rusting out. A friend of mine won’t drink hot water from the tap 'cause he thinks it has all kinds of extra precipitated scale from the water in it. He says “look into a kettle - see all that scaley stuff?? that’s in the water heater too”.
What he doesn’t seem capable of grasping is that these various carbonates have dissolved out of the water as it got too hot or evaporated a bit, therefore the hot water that left the vessel now has less dissolved minerals than the incoming water and the cold tap water, which still has everything in it. You almost get a very limited kind of distillation when you put water through the boiler.
I don’t see how stagnation would hurt either… for one thing the water is constantly cooling off/heating up and circulating a bit, and does so quite a bit when you drain some off and new water comes in to replace it. This water is also hot (not just warm), so you’d think less nerbies would be able to grow in it - not to mention that the hot water is chlorinated or treated just like the cold anyways. Cold water also sits just as stagnant in the pipes when the tap isn’t on, so I wouldn’t worry about that.
Most problems we see, in the drinking water industry, about “stinky water” are those larger homes, or vacation homes, where the hot water sits for long periods without being used.
The chemical used to sterilize the water is chlorine. Over a 24 hour period, the chlorine dissipates. Remember how you can draw water and let it sit for 24 hours before putting it in your goldfish aquarium? If let water sit for hours, bacteria normally present in the system are free to breed. Some of these organisms are quite capable of living under the high temps of the water heater.
I NEVER use hot tap water for cooking. Especially making tea or Koolaid, or boiling vegetables. Using the cold water tap (which runs freely thus bringing the chlorine all thru the cold water system) is safer.
This is not to say that the well water which most of us rely upon contains contaminants. It usually doesn’t . It is the pipeline system which is vulnerable. You have leaks, which must be fixed; and if pressure is drawn down because of breaks in the main, contaminants are siphoned in. The water coming thru your cold tap is better protected than that water which sat in your water heater, because the disenfectant (chorine) is added continually.
Most problems we see, in the drinking water industry, about “stinky water” are those larger homes, or vacation homes, where the hot water sits for long periods without being used.
The chemical used to sterilize the water is chlorine. Over a 24 hour period, the chlorine dissipates. Remember how you can draw water and let it sit for 24 hours before putting it in your goldfish aquarium? If let water sit for hours, bacteria normally present in the system are free to breed. Some of these organisms are quite capable of living under the high temps of the water heater.
I NEVER use hot tap water for cooking. Especially making tea or Koolaid, or boiling vegetables. Using the cold water tap (which runs freely thus bringing the chlorine all thru the cold water system) is safer.
This is not to say that the well water which most of us rely upon contains contaminants. It usually doesn’t . It is the pipeline system which is vulnerable. You have leaks, which must be fixed; and if pressure is drawn down because of breaks in the main, contaminants are siphoned in. The water coming thru your cold tap is better protected than that water which sat in your water heater, because the disenfectant (chorine) is added continually.
But NinetyWt the dangers you raise are on the assumption that the throughput of hot water is low. In fact, I would think that our throughput of hot water may be higher than our throughput of cold water, given that much of our bulk water usage (showers, baths, dishwasher, washing machine) is hot not cold. Well OK maybe not higher, but high. High enough that in fact, we often run out (which is a whole other no doubt soon to be expensive issue).
So there is not much reason to think that the hot water is any more likely to be “older” than the cold.
Given that, there would seem no basis for worrying in our case.
princhester, what you say about total run thru is probably true. Still, i would not drink hot tap water. The heat of the water heater will cook out the chlorine. Until better methods are developed to keep the water mains free of contaminants, I would strictly drink out of the cold tap.
Worry? I wouldnt’ worry. Many childrens’ magazines in the days of my daughter’s infancy suggested making formula in the a.m. with the hottest, best water out of the hot tap. She’s lived so far to the ripe old age of 17. I don’t think you really have a concern.
Oh, I have a concern, all right. But it’s not a concern that hot water may be unhealthy, it’s a concern in relation to proving my wife and mother in law wrong
I’m kind of hoping someone with way too much time on their hands has actually done a study and proven that bacteria counts are no higher in hot than in cold.
But no one’s jumped in with a post to that effect so far, dammit.
The reason for not drinking the hot tap water is to avoid the dissolved metals. Hot water holds more metals in solution. Typical concentrations of metals in hot water from the tap? I don’t know, but I’ll try and find out some specifics tomorrow at the lab, from the women who run the metals analyses on drinking water.
And cold water from the tap isn’t much better if it’s been sitting in the household pipes for a while, but it should have a higher chlorine residual, at least. The freshest water comes from the large diameter water main nearby. To get at this fresh stuff, simply run your faucet for a couple of minutes until the water suddenly turns noticably colder.
Lead is an issue for some homes. The solder used to “sweat” copper pipes together uses lead (and possibly antimony and other fun stuff). When hot water sits in a pipe some of the lead might leach out. But we are taking about really small amounts. Nonetheless, there is a big push on to ban lead in solder for pipes. (I think it’s already in effect, at least around here.)
If you are really paranoid, avoid the first draw of hot water in the a.m. After someone’s taken a shower or the dishwasher has run, the hot water is nearly identical to the cold. (Just “flush” the pipe to get “fresh” water in your branch.)
Strange that people bring up Chlorine depletion as a problem. There’s a whole category of folk that consider that an advantage. (Both for taste and health.)
Talked to one of the ladies who analyzes metals in my city’s drinking water today. She said that Aluminum and Magnesium are some of the big culprits.
Turns out they come from the sacrificial anode inside the hot water heater.
I couldn’t get any relative numbers to compare with fresh, clean drinking water. She just said it varies a lot, due to different patterns of hot water usage.
Culprits? Magnesium is a necessary mineral, some people even take supplements. Aluminum in small amounts is generally regarded as harmless (techno-idjits once tried to link it to Alzheimers but were strongly rebutted).
Given the possible size of such rods, their expected lifetimes and the limit on how much water a person could drink a day, we are talking about trace amounts.
Some domestic hot water systems have a hot water cylinder and an expansion/header tank in the roof void; this tank is often left without a cover, or the cover is ill-fitting, allowing nasties to drop in, not that the odd bug is going to kill you, but if it remains in the water for a while it can provide the nutrients required for bacterial growth.
I have heard of people discovering the remains of rats or birds in the header tanks.
I believe the problem comes not from the heating of the water itself, but the sediment that builds up in the tank. I know it can affect the taste and the smell of the hot water, but I’m not sure if there is anything particularly unhealthy about it. If you flush your tank periodically, there’s nothing really to worry about I’d bet. If you don’t, well there’s probably a lot of sediment in there. I would doubt anything could grow in it, so I would bet it doesn’t pose a health hazard, but it could affect the taste of what you’re using it for.
Me, I know I don’t flush my tank often enough, so it would probably not be the greatest tasting stuff (although I doubt I could differentiate it from the rest of my house water, as it is nasty).
Mangetout, I believe such header tanks are in regular use in the UK, (hence the predilictions of my protagonists as outlined in the OP) but never in Oz.
Dilbert you would appear to be missing a point already made earlier: the sediment comes from the water. Therefore, if some of it settles out in the hot water tank, that means there is less of it that makes it through to the hot water tap than to the cold water tap, not the other way around.
I believe the problem comes not from the heating of the water itself, but the sediment that builds up in the tank. I know it can affect the taste and the smell of the hot water, but I’m not sure if there is anything particularly unhealthy about it. If you flush your tank periodically, there’s nothing really to worry about I’d bet. If you don’t, well there’s probably a lot of sediment in there. I would doubt anything could grow in it, so I would bet it doesn’t pose a health hazard, but it could affect the taste of what you’re using it for.
Me, I know I don’t flush my tank often enough, so it would probably not be the greatest tasting stuff (although I doubt I could differentiate it from the rest of my house water, as it is nasty).
