According to the EPA: "Hot water dissolves lead more quickly than cold water and is therefore more likely to contain greater amounts of lead. Never use water from the hot water tap for drinking, cooking, or making baby formula."
The applicability of this advice is probably quite variable.
In addition to this, tank water heater systems include a sacrificial anode rod.
Water heater tanks include different metals in contact with the water, which creates a galvanic cell. Over time this corrodes the least noble metal. The rod is added in the design to corrode before pipes do. The rod is usually magnesium, aluminum or aluminum-zinc. It slowly but steadily leeches out the rod metal into the hot water supply.
Serious question: do we still install lead pipes anywhere? If no, when would be the threshold year where installation started to drop off for various reasons? I have heard that pex plumbing has taken over, but I have no idea if that is only for residential, but commercial use is something else entirely.