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Comment by tomjakubowski | Hacker News Reader

Why is it specially allowed in hot water lines?

It's not allowed in any water lines used for drinking or cooking. I would read that as not allowed on hot water lines serving the kitchen for sure (and I suspect most plumbers would agree).

The warning on items from my plumbing supply house for lead containing items is prominent, pops up on each "add to cart", and says "This product does not comply with the “Safe Drinking Water Act,” which requires that products meet low-lead standards in order to be used in systems providing water for human consumption (drinking or cooking). This item is for non-potable (non-human consumption) water applications only."

It is allowed in hydronic heating, HVAC/R, and irrigation fittings (which of course don't have a human consumption element to them).

I think that is allowed because we don’t drink from the hot water tap.

But when I googled hot water tap the first images it showed were... uh...

https://www.sinks-taps.com/articles/2018/9/21/the-benefits-o...

hahaha ok, but that product is a hot-water heater built into your kitchen tap to do away with your hot water kettle. Presumably, that's not plumbed to your teapot with a lead boiler and faucet. (weird, "plumbed" means "leaded")

...We don't...? Who?

In the past it was common knowledge not to. It's of much more uncertainty as house plumbing has changed.

That's because it is primarily a historical artifact[0]. Most modern plumbing heats water on-demand, which pretty much entirely avoids the risk of storage tank contamination or Legionella.

[0]: https://www.youtube.com/watch?v=HfHgUu_8KgA

>Most modern plumbing heats water on-demand

Where is this the case? These kind of things are extremely locational and here in the US it seems like 45 gallon hot water tanks are still the norm. We had a fad with "on demand" hot water heating but everyone gave up on it when the "it saves you money" part didn't work so well.

Here in Europe the money saving works really well. The issue is that you need a lot of power to heat on demand. Meaning natural gas. Having an electrical connection strong enough to heat water for a shower is rare.

I wouldn’t consider on-demand heaters to be all that modern. Places that use on-demand water heaters are now at a disadvantage because it is much more challenging to switch away from fossil fuels over to electric. Tanks, especially with a heat pump, can provide all the heating a household needs through a standard 120V15A socket. For on demand electric water heating you’re looking at upgrading main panels to supply an additional 240V20A and even that will struggle to heat the water enough in some winter climates.

Storage tanks are extremely common in Australia, but they are run hot enough to kill anything and then get mixed with cold water to bring it back to the desired temp.

I know people who fill their water boiler with hot tap water ...

Me too and it always felt wrong to me and never did it myself. Now I have a solid reason.

Oh and you should not drink directly from the warm tab water, as warm water that was standing some time, has way more microorganisms .. a point my 2 year old is not yet accepting.

I fill my water distiller with hot tap water. Guaranteed to be safe. Yes, I'm talking about a machine that boils the water, collects the steam, and condenses it back to water. It removes absolutely everything.

You shouldn't drink distilled water for a prolonged time as it will desalinate your body and depreve it from rare minerals.

A banana probably has more than enough electrolytes to counter this

Absolutely everything… that has a boiling point higher than water’s. It won’t do anything to remove alcohol, for instance. Or any other contamination that boils off before water does.

Ofc you could discard the head and tail of your distillation operation…

Yes, you're right in a pedantic way =). I trust that my city's tap water doesn't have alcohol in it. After all, I previously and many people still drink it without extra filtering, and it's safe enough to do so.

Relatedly, the standard technique in alcohol distillation is to discard the head because it contains toxic methanol. https://youtu.be/a1IruS1bKN8?t=672

But alcohol isn't the only thing that has a boiling point lower than water.

The hot tap water likely has more dissolved solids in it. Over time that will precipitate into your distiller.

You can remove that by running a few cycles with vinegar. But if you fill with cold water, you'll get fewer deposits and have to clean less often.

Restaurants are sometimes equipped with hot water lines from the water district and a filler tap right above or near the stove so that boiling water doesn't take so long.

If I'm making tea I do. I can't imagine that lead is boiling off...

That's a terrible way to make tea, fwiw.

I want to stress that I actually don't give a shit (I am not that into tea, I just drink it sometimes, it's not a big deal to me), but I am curious as to why.

Unrelated to the tea, but cold water is somewhat safer to drink than water coming from your boiler, that's why.

IDK, they said "a terrible way to make tea", I'm assuming there's some sorta tea lore that I'm unaware of

There are tea drinkers that believe very strongly in using water that isn't "stale" (eg, leftover in the kettle from the last time). Presumably water from the hot water tap would be stale for similar reasons.

I think the theory is that "stale" water lacks sufficient oxygen for tea brewing to fully brew or something.

It's not O2: if you let water sit out, various things (including CO2) dissolve in it, making it slightly acidic and taste stale.

I'm not a big tea drinker, but I am definitely not a super fan of water that's been sitting out a day. There's not been time for stuff to grow in it yet, but it still tastes gross.

That makes sense.

Fill a cup with cool water and take a sip before you go to sleep. Tastes great, right? Taste it eight hours later when you get up in the morning. It takes on an acrid taste.

It's not hot enough. Black tea is usually brewed with boiling hot water around 95 - 100 °C. Green tea is usually brewed a bit lower than that at around 80 °C. But the domestic hot water supply is typically around 50 °C, to prevent burns. It'll be very weak, and probably taste a bit off. Same with coffee, or anything else that requires boiling hot water.

I don't drink tea made from hot water. I put hot water into a pot and heat it up further.

You should switch to using the cold water tap to fill your kettle! Also, when you see what kind of build up can happen in a hot water heater, you'll definitely want to avoid drinking from the hot water tap.

https://www.youtube.com/watch?v=kAzKts6Wp1Q&t=207s

That's not lead, that's limescale[1]. Dissolved limestone is carried through the pipes, and settles out as scale.

[1] https://en.wikipedia.org/wiki/Limescale

Yes, I didn't say it was lead. It is just a dirty, unpleasant container. Not where you want to get your drinking water, especially for tea.

It isn't just limescale in your hot water heater, it is whatever your water pipe carries in and accumulates in the tank. We lived at the beach and had to flush sand out every couple years.

Your cold water carries the same junk into your tea. It’s just missing the settling tank that would separate it out.

It is potentially a decade of accumulated junk in the hot water heater. If you aren't able to taste the difference, the data backs up the issue with drinking hot water.

https://www.nytimes.com/2008/01/29/health/29real.html

https://blogs.edf.org/health/2018/02/26/lead-hot-water-issue...

https://www.denverwater.org/tap/psa-dont-drink-or-cook-with-...

Make up your mind, does it come in or go out of the hot water tank?

It can’t both accumulate and leave at the same time.

False assumption it needs to accumulate and leave at the same time.

If the water was already hot because I was doing something else, I'll make soup or pasta with a pot of hot water. If the kitchen were closer to my water heater, I'd do it more consistently.

You're never supposed to cook with hot tap water. Even if lead is not a concern, there are other possible contaminants that can leech from plastic and copper pipes, or from the tank itself.

This is not taught in the US and we blend hot and cold together. Why are the lines blended at the faucet if that’s the case?

There's a lot that's not formally taught in the US. But I'm in the US and this is a thing. The blended faucets are fine. If it was set to hot or some blend with hot in it, you set it to cold and let it run for 1-3 seconds.

No, it’s blended because hot water is fine in the US. We don’t use hot water tanks that sit on rooftops and accumulate bird shit.

If you ever find yourself cleaning the inside of a hot water heater some day, it will disabuse you of that habit.

I'm sure it's mostly harmless, but they accumulate a truly horrific amount of mineral deposits and other weird gunk in there.

They accumulate gunk that was present in the cold water supply.

If its not quite hot enough you can end up having a nice incubator for bacteria

Yes, but water coming from the cold water tap has spent less time sitting in that accumulated stuff.

There can't be more minerals coming out than what went in though. It's not like calcium grows. Maybe it might break off and come out as some concentrated chunks, but overall there would have to be less coming out for it to accumulate in the tank.

Seems like the presence of the accumulated gunk in the cylinder means the hot water must be cleaner by definition? The accumulation being the net difference between what was dissolved in the incoming water and what is dissolved in the outgoing water.

With the exception of gunk that is from the lining of the cylinder itself of course.

Yeah, so the gunk has less time to fall out of the cold water.

Looking inside a kettle in London provides the same experience (at least when I lived there).

Now we live on rain water and the inside of the kettle is pristine, despite bird crap on our roof and flora in the guttering.

For things like an instapot where you add a cup of water to it, you are actually supposed to use distilled water. I used tap for years with mine and got all sorts of mineralization. It took quite a bit of vinegar to get that off, and now everything looks pristine since I have been using distilled water. You might consider using it for your next kettle, although perhaps the minerals in tap do something to the taste of the tea.

Do you buy hundreds of liters of distilled water? That doesnt sound practical

That's why modern kettles can be cleaned. I clean the mineral deposits out of mine once a year or so.

Hot water heating is where it is allowed. Some houses have hot water heating which should never touch tap water and so lead won't be a problem (well it might be to plumbers working on it).

Lead is an amazing material, too bad it is toxic, because from a materials stand point it is very useful to put a little into many different metals to useful properties.

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