- if you go to lowes, many of the fittings for hot water pipes are made of lead

- my cold water supply doesn't sit in a big 50+ gallon tub for 1-2 days at a time (I don't think we fully empty it but every other day, on kid bath night)

- old hot water heaters will fill with sediments and other buildup

So like, on a scale of drinking sewage to drinking dew collected from the leaves of Yggdrasil? It's probably about the same as drinking (cold) tap water. But also like, given a choice, I'll probably go for the cold tap.