Hello! Around 9 years ago, we did a major rebuild of our house. Basically all the plumbing is new and we put in tankless water heaters.
Growing up, I was told that you shouldn’t drink/cook with water from the water heater. I think it was because, with older pipes and a tank header, all kinds of bad chemicals could end up in the water (lead was probably the biggest concern, I guess). However, with new plumbing, I’m sure there are no lead pipes leading to the taps (could still be on the outflow, for all I know), and the tankless heaters don’t have the water long enough to precipitate anything out.
We also have a water conditioner, if that helps. I imagine it would further remove some minerals.
Anyway, my question is, is it safe to use the water from my hot water taps to cook or drink?
Yes, It’s safe. Assuming the water coming into your house is potable then nothing will happen to change that in its short trip through the tankless heater.
That was quick! Thanks! Yes, the water is potable.
One additional question – was it really a problem with water heaters with tanks? Or, was it one of those incorrect pieces of received wisdom? How about with tanks but no lead pipes? Just curious.
Back in the days of lead solder and copper pipes, it was more of an issue because the water in a water heater tends to just sit there all day long. Lead and copper from the pipes along with other minerals that have built up in the sediment at the bottom of the tank tend to leach into the water, and that’s basically what the problem was. Water heaters have a drain valve so that you can clean the sediment out of them, but I have never personally known anyone who regularly cleaned the sediment out of their water heaters.
That said, it’s not like the water sitting in the tank was deadly poisonous or anything. It’s not the best stuff to drink in the long term, but if you need water (like you’re in an area hit by a natural disaster and there’s no water) you can drink the stuff that’s been sitting in the water heater, no biggie.
With a tankless system, or with a boiler furnace like what I have (which is also tankless), the water doesn’t sit and doesn’t get a chance to leach materials from sediments and pipes, so there’s not even that issue.
I know your questions have been answered, but I am curious about something as well. As engineer_comp_geek said, I also have not known anyone to actually flush the sediment out. What could it possibly be anyhow? Just mineral deposts? I know of the drain valve, but it always seems to sit a little higher than the lower end of the tank, so how could all of the sediment get flushed out anyway? Just pressure and hoping it clears it? Genuinely curious.
Also for OP, to expand on it, I believe lead solder was used on older copper pipes and it would leech into the water after some time sitting and chances are you do not have actual lead pipes. As said above though, it really doesn’t matter, it is definitely safe to drink. Also, using tap-mounted or under sink water purifiers will usually bring the lead and other leeched stuff under control anyhow. Those purifiers do work on hot water too, just not as well and lower the life of the filters apparently (according to PUR). If you want it a little fresher tasting, just let it run for 10-20 seconds before using it.
Under sink water filters/reverse osmosis systems are something everyone should have. They are not very expensive, burning through maybe $30-$50 in consumables per years for a family of 4. The reason is that you do not control the city’s water supply to your house, and a screw-up that contaminates it can and does happen frequently. Basic activated carbon systems will strip the lead and chlorine, reverse osmosis systems do a better job and also strip basically every contaminant to lower levels. (after RO, it’s nearly the same as distilled water) Also, chlorine tastes bad.
Turns out, in many cities there still are thousands of miles of lead pipes in the ground. This is legal and semi-safe, as long as the city does a good job of controlling the water pH. What happened in Flint was they switched water source and also failed to add additives that would have corrected for the pH difference.
Finally, with regards to drinking from the hot tap : in England, this is still a thing. Here’s a video explaining why. TLDR, it’s because the way hot water systems were fed in England, they used a tank vented to the atmosphere up in the attic and a boiler.
I’m rather shocked to hear this. I regularly flush my hot water heater. In fact I just did it a couple of weeks ago. The issue isn’t stuff from the sediment leaching into the water, it’s that the sediment reduces the efficiency of the heater by blocking the lower heating element. It can also cause the heater to fail earlier, reducing its life span.
And, for the record, drinking from the water heater after a brief outage is ok. But that is not recommended after a two month outage with still water sitting in tropical heat. </Lessons learned from Hurricane Ivan, 2004>
The more the water keeps moving, the less likely it could possibly pick up leechate from within the pipes. But it could pick up sediment that gets introduced to the pipes by a water main repair. As markn+ noted sediment from any source could build up in a traditional tank water heater. Switching to the new tankless system like the OP has donde will eliminate that problem.
I’m not understanding the concerns with sediments in a hot water tank, or how they could leach into the water (metals are a different matter). The typical sediments that build up are calcium and magnesium carbonates, which precipitate out of water because their solubility decreases as the temperature increases. They get deposited in the tank because the water can’t hold any more of them in solution; I’m not seeing how these sediments can leach into new water coming in. If anything, a hot water tank acts as both a filter which removes a small percentage of dissolved minerals.
Tank less heaters will still cause precipitation; that’s a physical property affected by temperature. They just don’t retain the sediments, which is usually not a problem as they flush out as there are only small quantities of them which go unnoticed. When the incoming water has a high concentration of dissolved minerals that precipitate at high temperatures, you can run into problems like I have in my house.
Namely, when I run the hot water I get chunks of mineral deposits spat out from the tap. If the tap doesn’t have a filter I get what looks like a handful of cat-litter sized sand/pebbles sitting on the bottom of the tub. If there is a filter or something like a shower head, it gets clogged up over a few months and stops flowing until I take it apart and remove all the chunks that formed.
Wow, thanks for that link. We recently moved into a house where I am positive the water heater hasn’t been flushed in years, if ever (it has the rumbling/popping described in the article). I’ve put off flushing it because I know the flush valve would clog immediately.
Sorry for the slight hijack, now returning you the the original thread…
A Guardian set of answers from readers in 2011. Some in America and England think it was from when actual lead was used, and in Wales, saying the water was acidic enough to leech copper; although most are doubtful as to it being dangerous.
I like this bit from Australia:
The water you are drinking is quite literally as old as the Earth. It is not fresh. Knowing that cold water comes freshly out of your tap, instead of your old boiler might make you feel better, but the reality is that either way the water came from some old pipe or tank or reservoir somewhere. It was not made freshly for your tea drinking pleasure.
As a child, it was my job to crawl into the loft and skim the dead birds out of the tank whenever the hot water started to smell funky. I still won’t drink from a hot tap, even if I know there’s no tank.
I heard this a while ago and it never quite made sense to me. The hot water tank and the cold water tap are fed from the same pipe coming in to the house, right? If the hot water tank builds up sediment because the water is stationary and various contaminants settle out, doesn’t that mean those same contaminants are present in the cold water, too?