Nos lavamos el pelo.
It is okay to say
Nos lavamos el pelo.
for "We wash our hair," in other words, we each wash the hair on our own heads?
2 Answers
Yes, that's correct.
Do you need to emphasize that each washes her/his own hair or is this just a simple "we wash our hair"? If no emphasis, I don't see what value "nos" adds. If you do want to emphasize that you aren't washing each other's hair, you need a bit more detail like "nos lavamos el pelo, cada una(o) su propio"