[brutusborn]

I think that depends where you live. Regulations in my location changed so that hot had to have the same configuration as cold (and supposedly the same potability?). Old houses in the area have separate taps for hot / cold whereas newer houses built after the change have combined hot/cold.

[GrantZvolsky]

If your water provider says it's potable I'm not going to question it, but I have yet to see a provider that makes such a claim about their hot water. It is difficult to make a statement that would apply worldwide, but where I live, it is easier to keep legionella out of cold water even if the infrastructure for hot and cold is the same.[1]

[1]: [Czech language] https://www.moni.cz/aktuality/tepla-voda-jako-pitna

[brutusborn]

We are supplied cold water which then goes through a hot water system. My understanding was that the new configuration required the use of check-valves to prevent backflow in such a way as to reduce the risk of cross-contamination between hot/cold. I'm guessing this is now irrelevant because hot water system standards have changed to reduce risk of corrosion / infections occurring, but there is also a chance I was getting mixed up with UK regulations [0].

[0] https://www.bbc.com/news/uk-england-42948046

[mbreese]

I don’t know why I think this, but I have it in my head that hot water heaters can have more mineral build up. This is why I always thought you should use cold water. Even though the hot was still drinkable, it might be harder water.

I have no idea if this is accurate.

[bpodgursky]

Yeah hot water can leach metals from the pipes that you really don't want to be drinking. This could either just taste bad, or add unhealthy amounts of lead and copper.

I would not use this plumber.

[rootusrootus]

We are fast approaching a time when all houses have pex. At this point we've been using it in new construction for decades, and most houses with original galvanized pipes are either already replaced with pex, or getting really close.

[bpodgursky]

I'll be honest, I also am not enthusiastic about drinking the volatile organics that hot water leaches out of polyethylene piping.

[checkyoursudo]

Give me copper or give me death.

[throwaway742]

I think you are vastly underestimating the age of the average house.

[EamonnMR]

Anecdotally, sometimes your hot water heater or holding tank will rust off a piece and turn your water iron-rich.

[bombcar]

Sometimes houses with water softeners will run non-softened water to the cold tap on the kitchen sink for cooking purposes, as some people don't want the salted water.

[jahewson]

Correct. Water heaters fill with sediment and should be flushed annually. Of course, nobody does this.

[notjtrig]

Hot water tanks and heating elements corrode over time.

[rootusrootus]

The tank is lined with glass, it shouldn't corrode unless that surface gets broken.

[sgerenser]

The sacrificial anode rod is designed to corrode. Depending on its composition that means higher concentration of aluminum or magnesium in the water.

[ars]

The hot water tank has a magnesium or aluminum anode. You should ABSOLUTELY not drink that water!!

Find an old tank and open it, and you'll never even consider drinking that water.