Duncanson 35 fresh water

Hello, we have a Duncanson 35 1978 and we cannot seem to find the fresh water tank. There is no deck filler either…
Also we cannot tell which taps are fresh water and what ones are salt water. Any help will be greatly appreciated.

Was water cleaner in 1978 than it is now? Perhaps it was used in fresh water and doesn’t have a tank - water is simply pumped from a through-hull opening.