I have some vague, probably erroneous memory of seeing some hot water fixture that said it wasn't meant for potable water, which made me believe that residential hot water in the USA may have different standards than cold. It might've been something related to the hot water heater. I know things like garden hoses and spigots do NOT meet the same standards for potable water and often have labels that make it clear.

Anyway, does hot water plumbing meet the same standards as cold water?

There may be other reasons why you don't want to drink hot water (eg, it might leach more easily), but I'm just curious about the standard practices in the USA.


Residential hot water in the USA is potable.

Source: (CIC) National Standard Plumbing Code 10.1 QUALITY OF WATER SUPPLY a. Only potable water shall be supplied to plumbing fixtures used for drinking, bathing, culinary use, laundry use, cleaning, or the processing of food, medical, or pharmaceutical products

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    However, hot water is more likely to pick up traces of chemicals, including lead from soldered pipes. It's a minor issue, but general advice is to prefer cold water for consumption, or to let the water run a little while to flush the pipes first. That last may be worth considering for cold water too, actually. – keshlam Jan 21 '17 at 0:23
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    If you have old pipes and/or lead solder, a test kit would tell you if you need to run a bit of water before running water for consumption. Applies to both hot and cold. – Aloysius Defenestrate Jan 21 '17 at 2:00

Some oddball facilities, such as freeway rest areas in remote and challenging locations, have water sourced in equally oddball ways. It may not be unsafe to clean with, but they don't want you drinking it.

A recently emerging issue is growth of legionella and other bacteria and exhaustion of chlorine in hot water tanks.

The workaround is to raise tanked heater temperature to a rather hot temperature. Which in turn means it's no longer safe to have old fashioned shower valves, and everything is going to either hotel style valves, or tankless heaters.

I know our old water heater had no chance of getting that hot, as I kept it max'd for longer showers. I'm sure there was a transitional time where the requirement was known but the heaters on the market were incapable of it (or incapable and still hit their mandated efficiency ratings). During such a time I could see such stickers.

  • The solution is a thermostatic mixing valve on the output of the water heater. This way the tank can be at 140-160F but the water leaving can be at no more than 120F. These same valves are also used for anti-scald protection. – Dan D. Jan 21 '17 at 5:22
  • @DanD. -- the solution is indeed a thermostatic mixing valve, but it goes at the bathroom, if not at individual fixtures (otherwise, you're making your dishwasher work harder for no good reason, and risking Legionella growth in infrequently used hot water pipework) – ThreePhaseEel Oct 24 '18 at 23:57

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