Years ago when I was just a kid I remember my old man telling me that you should never use water from the hot tap for making tea or coffee and it stuck with me ever since. Something to do with stuff in the hot water tank that you wouldn’t want to ingest.
It’s only taken me 40 odd years to query this but is there any truth in it? Would making instant coffee from the hot tap kill me?
My parents had the same stricture and my understanding was that it’s a preventative thing. If there’s a chance that lead solder has been used in the water pipes, hot water can leach out the lead and carry it through to the faucet. If you’re showering or doing dishes, no biggie but if you’re cooking, you may then ingest lead. I would totally believe it if it’s all hogwash, however. But that’s the explanation my parents gave me.
This has come up before. I’ll search, but I seem to remember the rationale boiled down to having something to do with hot water leeching toxins out of the plumbing. Whether the rationale was an actual thing to be concerned about, I can’t recall.
http://www.charlestonwater.com/water_faq.htm#hot_water_cooking
Charleston water is the water supplier for Charleston, SC. So I’m willing to trust them.
FWIW, my dad used to say the same thing, particularly citing the lead solder in pipe joints as the hazard.
Previous threads:
It depends.
If you have a typical water heater, like most folks these days, there are two concerns. The first is a higher concentration of impurities from your household plumbing, since hot water dissolves more impurities than cold water and the hot water in the tank tends to sit for a while. The second concern is that a lot of folks keep their hot water temperature much lower these days than they did in the past, both to conserve energy and also to make their water heaters last longer. The result is that bacteria that would have been killed in the older days of hotter water can now thrive at the more common lower temperatures.
On the other hand, if your hot water is heated on demand rather than sitting in a tank, then neither of the above issues really applies. If you have an old fashioned boiler furnace like I do, or you have a new-fangled on-demand electric heater that heats the water right before it comes out of your faucet, then there is no tank where hot water sits and absorbs lead and other metals from your plumbing, and no tank for bacteria to grow in either. The hot water in both of these systems was cold water right before you needed it, so it really doesn’t matter.
Most homes these days have a hot water tank.
I’ve heard also that the hot tap has less dissolved gas which effects the taste, though if your going to heat up the water anyway I’m not sure if there is going to be a difference.
What if you have an instant hot water dispenser installed by your kitchen faucet? Are those things somehow dangerous?
another issue is turbidity, stuff that doesn’t dissolve in the water. solids can settle out of your water in your hot water tank. the tank, glass lined, will also have a sacrificial anode which corrodes and has particles settle from. some of these solids get get stirred up and come with the water.
If I understand those correctly, they heat the water right there under your countertop, and are specifically designed to produce hot drinking water, so I would think any of the concerns associated with hot tap water would have been taken into consideration with those.
If you do have a hot water tank, and you empty it occasionally, you probably have seen the crap that tends to collect in there. That can be a turn-off for drinking the water.
-D/a
In all of these discussions, including all of the links to various public health officials saying “Don’t Drink Hot Water”, I’ve never seen any actual data. Yes, the mechanism sounds vaguely plausible: hot water can hold more solutes, or can dissolve more metals from the piping. But I’d love to see some actual measurements of water quality from typical household hot water sources as compared to the same cold water source (and upstream municipal supply).
For example, what might actually happen in the worst case sort of scenario of an old house with lots of lead solder? If the municipal water supply has (say) 5 ppb lead, would cold tap water have an increased level of, say, 10 ppb? Would the hot water then have an even higher level of 20 ppb? Or perhaps the differences would be negligible, i.e. the water only increases from 5 to 5.1 ppb in the short trip through household plumbing, and maybe all the way to 5.2 ppb if it’s hot.