There shouldn't be any cadmium in your plumbing. Copper while actually a nutrient in very very small doses, would only be a problem in severely corroded pipes where cold water isn't helping you.

Nobody in the last century+ has lead freshwater pipes.

That said, some of our underground infrastructure is very old, and those old iron pipes had fittings sealed with lead and oakum.

Water flowing through such pipes have pH and chemicals carefully controlled to avoid that lead corroding or dissolving. The Flint, Michigan disaster was a direct result of not managing water chemistry correctly, but there are hundreds if not thousands of communities at similar risk who are kept safe by water scientists and engineers doing their job correctly.

That said, hot water tanks do accumulate minute quantities of undesirable metals over time, and depending on a wide variety of variables between the water source and your tap it could result in unhealthy levels of things you don't want to consume.

So yeah, don't cook or drink from the hot water tap.