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Why you should drain your hot water heater regularly and not use hot water for drinking: https://blogs.edf.org/health/2018/02/26/lead-hot-water-issue-worth-tes

Why you should drain your hot water heater regularly and not use hot water for drinking: https://blogs.edf.org/health/2018/02/26/lead-hot-water-issue-worth-testing/ https://blogs.edf.org/health/2018/02/26/lead-hot-water-issue... They’re lead traps.

doubled112 3y ago
I was always taught to use cold water for anything to do with food. Never thought of lead.
- quickthrower2 3y ago
  Probably because hot water is stored and if it happens to go below a certain temperature bacteria can multiply
- bregma 3y ago
  Water that's been sitting in a heater tank is oxygen-deprived and tastes dull when you use it for food preparation. That's the main reason to use aerated cold water instead of water from the hot-water system.
- EnigmaFlare 3y ago
  In some houses, the hot water is fed by an open header tank in the ceiling. Whatever dust, dead mice or bird poos fall into that, can contaminate the tap water. I went off drinking hot water as a kid after seeing the deep layer of fine dust built up in the bottom of it.
  - samtho 3y ago
    As pointed out in a different comment thread here, that’s a header tank which was used in older, multi-level buildings where city water pressure was not adequate for the rise to upper floors. Builders would set up a tank that slowly filled using the lower pressure and could act as a sort of mini water tower for the building. This did not contain hot water, but there is a chance a hot water tank was using this supply.
    - EnigmaFlare 3y ago
      Where I lived, the cold water was at much higher pressure than hot. I assumed it was common for cold to be mains pressure and hot to be from a header tank when present. Maybe it was an unusual case of retrofitted hot water (house was likely built before the invention of hot water).
bgentry 3y ago
Unless you have a tankless water heater and no lead pipes in your house, in which case it’s fine to use the hot water from the tankless water heater for food / coffee / tea. At least that’s my understanding.
- __MatrixMan__ 3y ago
  That's my understanding also. I only do it if I was already using hot water recently though. It seems pretty wasteful to pour all of that perfectly good cold water down the drain while I wait for the hot stuff to get to the faucet.
- oooyay 3y ago
  I have a tankless water heater. Does anyone know how accurate these things are? https://www.amazon.com/Safe-Home-LEAD-Drinking-Water/dp/B091JKJSL4 https://www.amazon.com/Safe-Home-LEAD-Drinking-Water/dp/B091... I'm down to do some weekend science.
  - scruple 3y ago
    I have a tankless, too, and after reading the article and these comments had the same thoughts...
    - theGnuMe 3y ago
      Water sits in the pipes so I would still run it and still use cold water.
jzelinskie 3y ago
Does this mean I shouldn't be doing my dishes with hot water?
- lotsofpulp 3y ago
  I assume if you have a newer house with PVC or PEX piping, this is not a concern.
  - doubled112 3y ago
    Should we worry about plastics instead?
    - stephen_g 3y ago
      PEX (and polyethylene in general) is one of the least concerning plastics, it’s not worth worrying about on that front. (I wouldn’t want to drink out of PVC though since it often contains phthalates as a plasticiser).
      - exmadscientist 3y ago
        Rigid PVC has few if any plasticizers. (This makes sense: it isn't very plastic!) This is the type usually used for water pipe, at least around here. It's probably not very dangerous. Flexible PVC is nasty.
    - lazide 3y ago
      Almost certainly, though most of the problematic plasticizers (anecdotally) probably work themselves out in the first couple years. We likely won't see any real studies on it for awhile though, but [https://www.sciencedirect.com/science/article/abs/pii/S004896972101442X https://www.sciencedirect.com/science/article/abs/pii/S00489...] is concerning. "In the US, PEX pipe manufacturers often request a pipe to be certified in accordance with the NSF International/ANSI 61 Standard leaching procedure (NSF International, 1988). However, the results are not made public and the water that contacts the pipe for its first 90 days is discarded and not tested. Therefore, there is a general lack of available data to be used for an LCA on US PEX pipe products." Water in plastic pipes is pretty stanky at first, especially the first couple months/weeks. PEX has issues with permeability - it's highly oxygen and chemical permeable. Also contaminants from manufacture working themselves out. PVC has a lot of plasticizers and stabilizers, and warmer temps make it leach faster. Many of them endocrine disruptors. That said, no such thing as a free lunch. And as long as the water is kept moving, chances are it's fine after awhile. Avoid the 'stanky water fountain' effect by letting the water run a bit before drinking/using it if you're worried.
Infernal 3y ago
If it’s a lead trap… wouldn’t that mean the water that comes out has less lead in it than the water that goes in? Assuming the water going into the heater is the same as the water coming out of your cold tap.
- throwaway89201 3y ago
  No, the article states that lead particles from upstream get trapped inside the water heater, which then gradually dissolve, especially when left stagnant overnight.
  - mattmaroon 3y ago
    Right but all those particles just end up in your glass in the cold water supply right? Better they get trapped in heater.
    - anonymouskimmer 3y ago
      Whether or not it's a good idea would really depend on what percentage of hot versus cold water ends up consumed (versus used for non-consumption purposes). Over the lifetime of the undissolved lead accumulation.
    - adrianN 3y ago
      I believe elemental lead is not terrible when ingested, but lead ions are much worse.
      - Paul-Craft 3y ago
        Yeah, metallic lead is pretty safe to handle overall, as long as you don't inhale the dust. I wouldn't want to go trying to ingest it, but the amount of incidental exposure you'd get from handling, say, a lead brick at room temperature, is not much of a worry. Wash your hands after handling it, wear proper PPE, and you should be fine. Edit: this isn't counting stuff like using lead solder. In that case, ventilate the crap out of your work area (preferably doing the work under a hood), wear PPE, and clean any equipment used.
superseeplus 3y ago
Most dishwashers are connected to hot water. Some higher end dishwashers can work with cold water, but the cheaper ones don’t. Does this mean using a dishwasher is a problem as well?
- 15457345234 3y ago
  This must be a US-centric thing, having had many dishwashers in my time and having never seen one with anything other than a cold water inlet. I assume this is related to the availability of 230v/15A for the heater element.
  - wkipling 3y ago
    Must be. I'd say most dishwashers are connected to the mains supply and not pre heated.
  - crazygringo 3y ago
    If you have hot water, why wouldn't you use that for the water connection? My dishwasher has a heating element, but the colder the water is, the more it has to work. So if it's cheaper to use gas-powered hot water from the boiler than to heat it electrically, why wouldn't you? And it's there in the kitchen right next to the sink which has hot water available anyways, so it's kind of a no-brainer. Yes, I'm in the US -- you can see on a kind of average dishwasher installation manual [1], it specifically instructs you to connect it to a hot water line. [1] https://www.whirlpool.com/content/dam/global/documents/201012/installation-instructions-W10282559-RevA.pdf https://www.whirlpool.com/content/dam/global/documents/20101...
    - adrianN 3y ago
      My dishwasher uses sufficiently little water that it would get mostly cold water from the hot water pipe.
      - crazygringo 3y ago
        Yeah, the standard advice is actually to run your kitchen faucet on hot until you get hot water, before you start the dishwasher. I'm always rinsing off the bigger gunks of food with hot water anyways as I load the dishwasher, so it's hot already. At the end of the day it doesn't matter that much. The main point is just, if you have hot water available, it's hard to see why you wouldn't take advantage of that.
mattmaroon 3y ago
This is a really stupid testing method. They should have tested both water supplies at the faucet. This does seem to indicate the hot water tank is removing lead from the water and thus you would be better drinking it than cold unless something is going on between the heater and your faucet.
- stjohnswarts 3y ago
  drinking hot tap water is really dumb considering this and also legionnaire's disease potential
  - mattmaroon 3y ago
    Other way around. This would indicate cold water has more lead.
    - mattmaroon 3y ago
      Also, Legionnaires isn’t a risk from your water heater.
      - stjohnswarts 3y ago
        it is if you don't turn the temperature up high enough.
washadjeffmad 3y ago
This remarkably old advice from a time before modern water treatment, sacrificial anodes, and automated temperature control is also why so many recipes instruct to "fill a pot with cold water" before it's boiled. Although, seeing the inside of an old water heater is all anyone would need to convince them to leave the hot water for washing.
- mschuster91 3y ago
  Given that many people leave their plumbing/water system in their homes be just the way it is for decades, it's still wise advice.
- CalRobert 3y ago
  There are places where the hot water is in an open (!) container in the attic and it could have dead rodents, etc. in it. Ireland, for one - which is part of the persistence of separate hot/cold taps in bathrooms.
  - globular-toast 3y ago
    Yes, that's called a header tank. It's common throughout the UK too. It means low water pressure, especially upstairs. The actual hot water is still in an insulated tank within the house. The header tank holds cold water. Most new installations are unvented systems with no header tank, but this comes with its own tradeoffs. The hot/cold tap thing is funny. We were just taught not to drink from the bathroom tap at all. It still seems gross to me when people do or like in hotels where you have to.
    - denton-scratch 3y ago
      The header tank is to maintain pressurisation in the radiator heating system; modern "combi" boilers don't need a header tank.
  - Angostura 3y ago
    I think you might be thinking of the cold water tank in the attic that was historically used to feed decent cold water pressure to the upstairs taps only. This is why I was told to never drink out of the taps upstairs as a kid. Think these up much rarer these days. Hot water is always stored in an insulated hotwater cylinder in the UK, not open.
kleiba 3y ago
I don't follow. My hot water is heated up about 60cm before the tap, as it runs through. Is that a regional thing? Are you saying that you're keeping a large quantity of water at temperature at all times just in case someone might need it later? Wouldn't that be super inefficient energy-wise?
- I_Am_Nous 3y ago
  This is the standard North American approach, we have large insulated tanks that hold water at generally 38-48 degrees Celsius. My home uses a 40 gallon "water heater" using natural gas with an always burning pilot light. It's possible to "run out of hot water" as a result.
- argiopetech 3y ago
  The common statistics I've heard is 30% of household energy usage goes to keeping the hot water heater at temp. How much of your power usage is water heating?
  - woobar 3y ago
    Looked at my natural gas usage. In the summer it only used for water heating/keeping it hot at 10 therms/month. Total annual gas usage is 700+ therms. 12*10/700 = 17%. And this includes both heating and keeping it hot. This site [1] quotes 0.0113 therms to heat a gallon of water. 120 therms / 0.0113 / 365 = 29 gals of hot water per day. This place [2] estimates 41 gallons of hot water per day used during peak demand. My estimate is that we use more for showers, less for washers/dishwashers, same for faucets. Looks like I would spend all of my BTUs on heating these 29 gals of water every day. Most likely close to single digits %% for keeping it hot. [1]https://webbsupplycompany.com/scalesafe/what-does-it-cost-to-heat-your-water/ https://webbsupplycompany.com/scalesafe/what-does-it-cost-to... [2]https://michaelandson.com/blog/what-size-water-heater-do-i-need#:~:text=Using%20our%20list%20of%20appliances,Kitchen%20faucet%20%3D%204%20gallons https://michaelandson.com/blog/what-size-water-heater-do-i-n...
hammock 3y ago
Does a tankless/instant water heater avoid this problem?

doubled112 3y ago

I was always taught to use cold water for anything to do with food. Never thought of lead.

quickthrower2 3y ago
Probably because hot water is stored and if it happens to go below a certain temperature bacteria can multiply
bregma 3y ago
Water that's been sitting in a heater tank is oxygen-deprived and tastes dull when you use it for food preparation. That's the main reason to use aerated cold water instead of water from the hot-water system.
EnigmaFlare 3y ago
In some houses, the hot water is fed by an open header tank in the ceiling. Whatever dust, dead mice or bird poos fall into that, can contaminate the tap water. I went off drinking hot water as a kid after seeing the deep layer of fine dust built up in the bottom of it.
- samtho 3y ago
  As pointed out in a different comment thread here, that’s a header tank which was used in older, multi-level buildings where city water pressure was not adequate for the rise to upper floors. Builders would set up a tank that slowly filled using the lower pressure and could act as a sort of mini water tower for the building. This did not contain hot water, but there is a chance a hot water tank was using this supply.
  - EnigmaFlare 3y ago
    Where I lived, the cold water was at much higher pressure than hot. I assumed it was common for cold to be mains pressure and hot to be from a header tank when present. Maybe it was an unusual case of retrofitted hot water (house was likely built before the invention of hot water).

bgentry 3y ago

Unless you have a tankless water heater and no lead pipes in your house, in which case it’s fine to use the hot water from the tankless water heater for food / coffee / tea. At least that’s my understanding.

__MatrixMan__ 3y ago
That's my understanding also. I only do it if I was already using hot water recently though. It seems pretty wasteful to pour all of that perfectly good cold water down the drain while I wait for the hot stuff to get to the faucet.
oooyay 3y ago
I have a tankless water heater. Does anyone know how accurate these things are? https://www.amazon.com/Safe-Home-LEAD-Drinking-Water/dp/B091JKJSL4 https://www.amazon.com/Safe-Home-LEAD-Drinking-Water/dp/B091... I'm down to do some weekend science.
- scruple 3y ago
  I have a tankless, too, and after reading the article and these comments had the same thoughts...
  - theGnuMe 3y ago
    Water sits in the pipes so I would still run it and still use cold water.

jzelinskie 3y ago

Does this mean I shouldn't be doing my dishes with hot water?

lotsofpulp 3y ago
I assume if you have a newer house with PVC or PEX piping, this is not a concern.
- doubled112 3y ago
  Should we worry about plastics instead?
  - stephen_g 3y ago
    PEX (and polyethylene in general) is one of the least concerning plastics, it’s not worth worrying about on that front. (I wouldn’t want to drink out of PVC though since it often contains phthalates as a plasticiser).
    - exmadscientist 3y ago
      Rigid PVC has few if any plasticizers. (This makes sense: it isn't very plastic!) This is the type usually used for water pipe, at least around here. It's probably not very dangerous. Flexible PVC is nasty.
  - lazide 3y ago
    Almost certainly, though most of the problematic plasticizers (anecdotally) probably work themselves out in the first couple years. We likely won't see any real studies on it for awhile though, but [https://www.sciencedirect.com/science/article/abs/pii/S004896972101442X https://www.sciencedirect.com/science/article/abs/pii/S00489...] is concerning. "In the US, PEX pipe manufacturers often request a pipe to be certified in accordance with the NSF International/ANSI 61 Standard leaching procedure (NSF International, 1988). However, the results are not made public and the water that contacts the pipe for its first 90 days is discarded and not tested. Therefore, there is a general lack of available data to be used for an LCA on US PEX pipe products." Water in plastic pipes is pretty stanky at first, especially the first couple months/weeks. PEX has issues with permeability - it's highly oxygen and chemical permeable. Also contaminants from manufacture working themselves out. PVC has a lot of plasticizers and stabilizers, and warmer temps make it leach faster. Many of them endocrine disruptors. That said, no such thing as a free lunch. And as long as the water is kept moving, chances are it's fine after awhile. Avoid the 'stanky water fountain' effect by letting the water run a bit before drinking/using it if you're worried.

Infernal 3y ago

If it’s a lead trap… wouldn’t that mean the water that comes out has less lead in it than the water that goes in? Assuming the water going into the heater is the same as the water coming out of your cold tap.

throwaway89201 3y ago
No, the article states that lead particles from upstream get trapped inside the water heater, which then gradually dissolve, especially when left stagnant overnight.
- mattmaroon 3y ago
  Right but all those particles just end up in your glass in the cold water supply right? Better they get trapped in heater.
  - anonymouskimmer 3y ago
    Whether or not it's a good idea would really depend on what percentage of hot versus cold water ends up consumed (versus used for non-consumption purposes). Over the lifetime of the undissolved lead accumulation.
  - adrianN 3y ago
    I believe elemental lead is not terrible when ingested, but lead ions are much worse.
    - Paul-Craft 3y ago
      Yeah, metallic lead is pretty safe to handle overall, as long as you don't inhale the dust. I wouldn't want to go trying to ingest it, but the amount of incidental exposure you'd get from handling, say, a lead brick at room temperature, is not much of a worry. Wash your hands after handling it, wear proper PPE, and you should be fine. Edit: this isn't counting stuff like using lead solder. In that case, ventilate the crap out of your work area (preferably doing the work under a hood), wear PPE, and clean any equipment used.

superseeplus 3y ago

Most dishwashers are connected to hot water. Some higher end dishwashers can work with cold water, but the cheaper ones don’t. Does this mean using a dishwasher is a problem as well?

15457345234 3y ago
This must be a US-centric thing, having had many dishwashers in my time and having never seen one with anything other than a cold water inlet. I assume this is related to the availability of 230v/15A for the heater element.
- wkipling 3y ago
  Must be. I'd say most dishwashers are connected to the mains supply and not pre heated.
- crazygringo 3y ago
  If you have hot water, why wouldn't you use that for the water connection? My dishwasher has a heating element, but the colder the water is, the more it has to work. So if it's cheaper to use gas-powered hot water from the boiler than to heat it electrically, why wouldn't you? And it's there in the kitchen right next to the sink which has hot water available anyways, so it's kind of a no-brainer. Yes, I'm in the US -- you can see on a kind of average dishwasher installation manual [1], it specifically instructs you to connect it to a hot water line. [1] https://www.whirlpool.com/content/dam/global/documents/201012/installation-instructions-W10282559-RevA.pdf https://www.whirlpool.com/content/dam/global/documents/20101...
  - adrianN 3y ago
    My dishwasher uses sufficiently little water that it would get mostly cold water from the hot water pipe.
    - crazygringo 3y ago
      Yeah, the standard advice is actually to run your kitchen faucet on hot until you get hot water, before you start the dishwasher. I'm always rinsing off the bigger gunks of food with hot water anyways as I load the dishwasher, so it's hot already. At the end of the day it doesn't matter that much. The main point is just, if you have hot water available, it's hard to see why you wouldn't take advantage of that.

mattmaroon 3y ago

This is a really stupid testing method. They should have tested both water supplies at the faucet. This does seem to indicate the hot water tank is removing lead from the water and thus you would be better drinking it than cold unless something is going on between the heater and your faucet.

stjohnswarts 3y ago
drinking hot tap water is really dumb considering this and also legionnaire's disease potential
- mattmaroon 3y ago
  Other way around. This would indicate cold water has more lead.
  - mattmaroon 3y ago
    Also, Legionnaires isn’t a risk from your water heater.
    - stjohnswarts 3y ago
      it is if you don't turn the temperature up high enough.

washadjeffmad 3y ago

This remarkably old advice from a time before modern water treatment, sacrificial anodes, and automated temperature control is also why so many recipes instruct to "fill a pot with cold water" before it's boiled. Although, seeing the inside of an old water heater is all anyone would need to convince them to leave the hot water for washing.

mschuster91 3y ago
Given that many people leave their plumbing/water system in their homes be just the way it is for decades, it's still wise advice.
CalRobert 3y ago
There are places where the hot water is in an open (!) container in the attic and it could have dead rodents, etc. in it. Ireland, for one - which is part of the persistence of separate hot/cold taps in bathrooms.
- globular-toast 3y ago
  Yes, that's called a header tank. It's common throughout the UK too. It means low water pressure, especially upstairs. The actual hot water is still in an insulated tank within the house. The header tank holds cold water. Most new installations are unvented systems with no header tank, but this comes with its own tradeoffs. The hot/cold tap thing is funny. We were just taught not to drink from the bathroom tap at all. It still seems gross to me when people do or like in hotels where you have to.
  - denton-scratch 3y ago
    The header tank is to maintain pressurisation in the radiator heating system; modern "combi" boilers don't need a header tank.
- Angostura 3y ago
  I think you might be thinking of the cold water tank in the attic that was historically used to feed decent cold water pressure to the upstairs taps only. This is why I was told to never drink out of the taps upstairs as a kid. Think these up much rarer these days. Hot water is always stored in an insulated hotwater cylinder in the UK, not open.

kleiba 3y ago

I don't follow. My hot water is heated up about 60cm before the tap, as it runs through. Is that a regional thing? Are you saying that you're keeping a large quantity of water at temperature at all times just in case someone might need it later? Wouldn't that be super inefficient energy-wise?

I_Am_Nous 3y ago
This is the standard North American approach, we have large insulated tanks that hold water at generally 38-48 degrees Celsius. My home uses a 40 gallon "water heater" using natural gas with an always burning pilot light. It's possible to "run out of hot water" as a result.
argiopetech 3y ago
The common statistics I've heard is 30% of household energy usage goes to keeping the hot water heater at temp. How much of your power usage is water heating?
- woobar 3y ago
  Looked at my natural gas usage. In the summer it only used for water heating/keeping it hot at 10 therms/month. Total annual gas usage is 700+ therms. 12*10/700 = 17%. And this includes both heating and keeping it hot. This site [1] quotes 0.0113 therms to heat a gallon of water. 120 therms / 0.0113 / 365 = 29 gals of hot water per day. This place [2] estimates 41 gallons of hot water per day used during peak demand. My estimate is that we use more for showers, less for washers/dishwashers, same for faucets. Looks like I would spend all of my BTUs on heating these 29 gals of water every day. Most likely close to single digits %% for keeping it hot. [1]https://webbsupplycompany.com/scalesafe/what-does-it-cost-to-heat-your-water/ https://webbsupplycompany.com/scalesafe/what-does-it-cost-to... [2]https://michaelandson.com/blog/what-size-water-heater-do-i-need#:~:text=Using%20our%20list%20of%20appliances,Kitchen%20faucet%20%3D%204%20gallons https://michaelandson.com/blog/what-size-water-heater-do-i-n...

hammock 3y ago

Does a tankless/instant water heater avoid this problem?