Hot water dissolves lead more quickly than cold water and is therefore more likely to contain greater amounts of lead. Never use water from the hot water tap for drinking, cooking, or making baby formula.
That’s only true in America, where your Health and Safety Standards are shit.
Might be true in parts of Africa and China too, along with other places with a bad standard of human rights.
It’s still legal for plumbing parts that contain lead to be used here in Australia.
It was supposed to be banned last year but they extended the dead line twice because the plumbers were crying.
It’s now meant to be fully phased out in May 2026.
There may be more lead in your country than you think, even if lead pipes are banned.
Multiple schools here have had lead found in their water. It’s crazy.
Well, it’s not been legal in the UK since 1970 to sell or install lead plumbing.
And the official Department of Water Inspectors (https://dwi.gov.uk/) reported only 50 cases of lead pipes in last year’s inspection
The use of lead solder and brass fittings has only been illegal in the uk since 1999, and these are still legal to use in central heating systems. This leads to people having access to these fittings and products, and them being used illegally.
“WaterSafe Warning after Kitchen Fitter Fined for Illegal Use of Lead Solder on Water Pipes” https://www.watersafe.org.uk/news/latest_news/watersafe_warning_af/
Unfortunately this problem is sort of universal and I imagine if I google other countries I will find similar.
To be fair, lead solder is far far far less risky than last piping
That is a straw man argument, but I’ll indulge again.
No amount of lead is safe, and a random sampling of newly built houses testing water from the cold kitchen tap as well as hot and cold from the bathrooms found lead above the current regulatory limit, and 5 times higher than the proposed new regulatory limit.
https://leappalliance.org.uk/litw-blog-15/
https://www.ifeh.org/docs/scientificreports/scottish_new_homes_lead_survey_ summary.pdf
One study has shown a clear response in infants where blood lead levels increased by 1µg/dL with drinking water that exceeded 5 µg/L. This is already worrying since it is now believed that blood lead levels as low as 1-2µg/dL result in negative health effects associated with fertility, neurological, cardiovascular, and renal disorders.
https://thewaterprofessor.com/blogs/articles/drinking-water-lead-and-iq
Growing up in the US I learned this exact thing was why there were two taps in the UK instead of a shared tap. That and Legionnaires growing in the hot tanks.
Yeah that’s not been true for about 50 years.
We replaced all our lead, and it’s a legal requirement to if you find a lead pipe in a system, replace it no matter what (even in listed buildings) or disable the outputs entirely (the latter is more common in VERY OLD buildings, with people then adding a new system somewhere else, sometimes with exposed pipework rather than having to potentially damage walls.)
We also just don’t do hot water tanks any more usually, instead doing on-demand boilers.
Does mean that the hot runs cold for about a minute, but it balances out
The hot runs cold for a minute with a tank too. It takes awhile for it to reach the tap.
I’m sorry is this some kind of American joke i’m too European to understand?
It’s fr and not a joke. If you grow up here, you’re usually told. Some aren’t aware of it though. We keep giant hot water tanks ready to go.
This is the typical think most people have for old construction. Not sure about new construction. It’s usually stuck in a closet or the basement:
Wouldn’t that only apply if there’s lead plumbing inside your house in between the water heater and the tap?
Yeah this is fear mongering bullshit.
The reason you care about dissolved solids is because of minerals tasting like shit and making your food taste mineraly.
Yes, but there’s other metals than can dissolve in hot water, like copper and cadmium
There shouldn’t be any cadmium in your plumbing. Copper while actually a nutrient in very very small doses, would only be a problem in severely corroded pipes where cold water isn’t helping you.
Any heavy metals will accumulate in your water heater and the hot water could potentially keep it in suspension. I bet it’s worse if you have lead pipes.
Nobody in the last century+ has lead freshwater pipes.
That said, some of our underground infrastructure is very old, and those old iron pipes had fittings sealed with lead and oakum.
Water flowing through such pipes have pH and chemicals carefully controlled to avoid that lead corroding or dissolving. The Flint, Michigan disaster was a direct result of not managing water chemistry correctly, but there are hundreds if not thousands of communities at similar risk who are kept safe by water scientists and engineers doing their job correctly.
That said, hot water tanks do accumulate minute quantities of undesirable metals over time, and depending on a wide variety of variables between the water source and your tap it could result in unhealthy levels of things you don’t want to consume.
So yeah, don’t cook or drink from the hot water tap.
That’s not totally true. I’ve personally removed lead pipes from houses that were built in the 1940s to 1960-1961. They stopped that shit sometime in the '50s or very early '60s here in the US, depending on the state. So it would be true that no house built in the last 65-75 years would have lead pipes, any old houses that have been sitting empty for the last few decades may actually still have some lead pipes.
Well damn. Lead restrictions weren’t Federal law until 1986. TIL.
https://www.epa.gov/sdwa/use-lead-free-pipes-fittings-fixtures-solder-and-flux-drinking-water
Although some areas added local restrictions starting in the 1920’s, industry lobbies kept the things on the market for decades. Ugh.
Yeah the real reason is that the inside of a hot water storage tank is nasty. Because of the way heat flows up, the hot water fills from the bottom and drains from the top. All the sediment and dirt and minerals collect at the bottom.
This seems…questionable. The entire information given is two sentences. This seems like something an eighth grader wrote for a school project.
‘Hot water dissolves lead faster’. Ok, how much faster? I feel like the trip from the water heater to my sink is negligible even if I had lead pipes, which I don’t.
If anyone has anything more substantial, please post it.
Also, I fucking hate that I’m saying this, I don’t trust the content of .gov websites right now. The Trump administration has been mucking them up.
I’m not saying I disagree with the claim, just that I’d try to find another reputable source for it.
Chemical engineer here. The difference in temperature between your cold and hot water supplies is what the problem is, and I would imagine this is not a problem at all in modern plumbing systems. Your cold water supply is usually about 50-60 deg F (10-15 C) while your hot water supply us usually set to 140 F (60 C). Solubility of some lead salts in water are given in this table with lead chloride being about 0.8 g/100mL at 10 C and 1.98 g/100mL at 60 C, so about 2.5x more soluble. The rate itself is a more complicated relationship, but it increases rapidly as well. Temperature has a big effect on these things.
Okay so this might be a weird question but, what’s the difference between undissolved lead and dissolved lead? Like, if there’s undissolved lead in cold water isn’t that still a problem? Why is it dangerous (or more dangerous) if it’s dissolved?
Clarification edit: Because you heat the water in your own home, so the lead would be still coming in through the supply, right?
The difference is that solid lead stays in the pipe and doesn’t get to you, the dissolution matters because the lead from the pipe dissolving is how it gets in the water in the first place. You aren’t really making any lead that was already in the water worse, but a lot of people live in older houses that have lead pipes or copper pipes with lead solder. If your house doesn’t have these, then it’s really not an issue.
So if you don’t have lead pipes it doesn’t matter?
Or copper pipes with lead solder.
When I moved into my house, I ran tests on my tap water, and found that my hot water had higher levels of iron and other metals dissolved in it. This is likely corrosion from the water heater tank. After I replaced the anode rod, the tests came out nearly identical.
All of the levels I found were within the legal limits for human consumption, so it would’ve been fine… But maybe there are cases where that isn’t true. The tests were very cheap, and Home Depot near me offers a 3 test kit (including lead) for free, near the water filter section. It’s worth testing to be certain.
Ah, so it was water heater corrosion. That makes more sense.
No lead pipes. 70C water temp against legionella. Yearly water quality tests in all public buildings. Drinkable tap water by law in any rental property. Europe <3
I’m in Europe too and it’s not recommended that you drink hot tap water. It’s just the possibility of stuff in it.
Even without lead pipes, if you have an electric water heater, the sacrificial anode rod leaches all sorts of shit. Seriously, just use cool water in a kettle. Mine usually takes less time than my pipes do to warm up when washing dishes.
If you have a high pressure hot water system, then the heater doesn’t touch what comes out of the tap. In those you have a closed system from the heating to a tank. That tank contains fresh water, but the heating loop only interacts with it via a heat exchanger.
As I’m not in the industry, what would you estimate the percentage of systems that is?
A new home in the United States does not have lead pipes inside of it. There could be lead pipes outside, but from the water heater to the tap will definitely not be lead.
Some people mentioned hot water heater buildup. But this is supposed to be a new house so there is none. Also it would depend on the style of water heater. As well as the incoming water quality.
Some people also mentioned electric kettles. Those are not as common as you might believe in the United States. Of course it varies but this is not the UK.
Statesian here. I have one kettle in my bedroom one in my kitchen, and one in my office. Tea waits for no man
A tea-drinker in Yankeeland? Traitor! :P
i know i know i’ll go jump in the harbor
It’s ok. I am a Canadian. I sympathize
In the early 70s the city I used to live in replaced all their old wooden water lines with concrete/asbestos pipes. They are now digging up the asbestos lines and replacing them with plastic. I do not know what the eventual plumbing will look like once they find out how the plastic is killing them.
Probably start installing wood plumbing.
For countries without lead issues, it is still a bad idea as hot water tanks can be hosts to a bunch of shit you definitely don’t want to ingest.
What if I don’t live in America, and my local infrastructure is sanitary?
America’s water infra is fine. Flint was a case of mismanaging the water supply. (Neat write up in this thread.) Jackson Mississippi is the only other place I’m aware of modern issues, and I wouldn’t take MS of an example of American anything except for “bottom of the barrel everything”.
It’s actually common knowledge that the vast majority of American water infrastructure is now nearly 100 years out of date, and Flint was just one regional example of potential waiting crises.
Source(s):
John Oliver Brought Out Sesame Street’s Elmo to Explain How We Can Stop Poisoning Our Children
The Lead Pipes in Flint Are a Tiny Part of a Huge Lead Problem
Impossible, as the American band Rammstein once said “We’re all living in Amerika, Amerika ist Vunderbar”
And then the rest of the song is in
GermanFar Western Pacific AmericanThe same advice applies
The post is rather thin, but I was initially upset about this post because I can’t read.
I was like: I’m going to drink hot water whether you like it or not! Took a while for my brain to process “hot tap water”.
Pretty sure most pipes don’t have have lead these days but lead the soldering in the joints of the pipes it is still pretty common
Tons of old houses have lead fixtures still, unless they’ve personally paid a plumber to replace all of the pipes in the building.
Have you ever smelled or descaled the inside of an old hot water tank? Its delightfully putrid and I would never want to drink the stuff coming out of there whether its technically safe or not
Wouldn’t all the dishes and utensils be exposed to lead when you use the dishwasher then? Or is it negligible as long as it’s not directly ingested?
I think it’s negligible compared to ingesting. I think most dishwashers do a final cold rinse, yeah? I could be wrong on that though.
I’ve never seen a dishwasher with 2 supply lines, they usually only hooked to hot.
Or cold with an internal heater, but still a single supply line.
We need that dishwasher guy to look into all of this.
He did already and that’s why we know most dishwashers (in the US) are fed by one line coming from the hot water tap.
I mean about the hot water having lead and other heavy metals part.
The steam that comes out of dishwashers I’ve used after washing would seem to indicate otherwise. Wouldn’t that temperature shock be dangerous to the ceramics?
Did a bit of research and there is a lot of disagreement on whether dishwashers should be connected to hot or cold supply lines. Might depend on the model somewhat.
It mostly depends on where you are in the world and what the wiring is designed for. 220V heating elements are abundantly powerful enough to heat water of any temperature to a useful temperature within the early stages of a wash cycle, and dishwashers with such heating elements are usually designed for cold water, for consistency, because the water in the pipes is always room temperature at first anyway. In places where the dishwasher is built for, and will be connected to 110V electrical supply, they will need the water to be pre-heated (including running the hot tap at the sink where they are plumbed from). If you read the manual, it almost certainly says so.
No matter what voltage they are designed for, they are almost exactly the same in all other respects. You might assume your dishwasher is smart enough to know what temperature the water is and that its magic electronics can run the water long enough or run the heater long enough or do something to make sure it gets to the specified temperature at some point before the cycle is considered done, however in basically all cases it does not, despite all the marketing bullshit trying to tell you how smart they are, they are actually very simple machines and they operate on nothing but very simple, factory-designed timers and cycles in all but the most esoteric designs. They are not smart enough to properly heat the water and almost none of them even have any sensor to detect the temperature or control the heating element in any useful way besides hopefully making sure it doesn’t burn your house down. They work because the combination of the heating element and the water supply together are enough to eventually make the water hot enough to wash properly. On 220V it’s easier to specify the use of the cold water because that is actually a pretty consistent temperature and the necessary heating times can then be set pretty reliably at the factory. On 110V you have to use hot water, and you have to make sure it’s actually hot in the pipes when the machine starts filling. The latter is obviously less desirable, but it’s the only way to get a proper wash out of 110V dishwashers. It’s a crapshoot, North Americans don’t generally know or do this, and the quality of the wash suffers accordingly. But they simply don’t make them any other way. Maybe they should change. But they haven’t. This is what we’re stuck with.
So basically if you have 110V dishwasher you need to hook it up to hot water and make sure the water gets hot before it fills if you expect them to wash properly. That’s just the reality of how they’re designed. 220V = cold water, 110V = hot water. That’s basically universal in the regions where each power standard is used. Unless you take a European/Asian 220V dishwasher and run the 220V wiring to hook it up in North America intentionally, but nobody actually does that, and you’re not going to find it was done in your house by surprise.
It really doesn’t have anything to do with 220v vs 120v systems. You can easily boil water with 15 amps at 120 volts. We used to have dishwashers with strong enough heating elements in the US to do this from cold running on 120v. It is a lot more to do with the efficiency standards set by Department of Energy, starting in 1994 and then further restricted in 2013 to maximum 307 KWh/year and 5 gallons of water per cycle. Prior to this, dishwashers in the US worked very differently than they do today. This is also why dishwashers in the US do a terrible job of drying dishes now - not enough energy to power a bigger heating element like they used to have.
On top of that, many current built and sold machines (at least in the US) are in fact more complicated than let on above, even the cheaper units, just not how you’d think. In order to try to squeeze as much performance out of those efficiency standards above, many have a turbidity sensor in the water flow path that checks how “dirty” the water is. If it doesn’t detect much, they will stop the cycle early, which means they “use less energy per year on average” (for the above legislation) and then can use more energy in a cycle “that needs it”. This often has a downside of people that significantly pre-rinse their dishes get really bad results from a dishwasher because the cycles will end so early the detergent hasn’t even fully dissolved yet and will be scattered and stuck to the dishes.
They are correct though that most don’t have temperature sensors in them, because frankly it doesn’t matter - they are either able to get to the needed temperature with the energy they are allowed or they aren’t. The only benefit of letting the machine know would be so it can display an error code to alert the user there is a water temperature problem (but most mfrs don’t want to do that because the average user won’t even bother looking up the error code and will just try to return the product or get a warranty service call, both of which cost the mfr money).
I can’t speak for outside the US, but in the US your dishwasher needs to be hooked up to a hot water line. The detergent won’t dissolve properly under 120ºF - 140ºF and they are restricted from using enough energy to get from “cold” to that temperature. Most of the manufacturers will even print in the manual that the water temperature coming in needs to be 120ºF so it can get hot enough to perform all functions.
If you hook up a US residential dishwasher to a cold supply line, you will be hand-washing all of your dishes.
Outside the us a lot of us have 230V power, so all of the dishwashers I’ve ever seen have their own heater and only hook up to cold.
I have a hot water recirc system that pumps hot water to the cold tap. Does that explain why I’ve started turning on my car’s hazard lights when it rains?
The other issue is a hotwater tank can breed bacteria if not hot enough, and if people are not thoroughly boiling and cooling for baby formula and just using hot tap water you could expose the babes to bacteria
