Campo Tures / Sand in Taufers is reachable by public transport.
2 trains and a bus
Train to Fortezza/Franzensfeste then a train to Brunico/Bruneck then the 450 bus. Overall travelling time ~ 2h15
The Reinbach waterfall
Difficult to say exactly.
at Cantuccio (Bad Winkel) there is a large car park which is the starting point for the nature area. This area is ~ 1mile from Campo Tures.
From Cantuccio go over the river/bridge to the car park
From the Car park to the Waterfall ~ 1h30
You might also be interested in the Burg Taufers /Taufers Castle.
It is on the opposite side of the village to Cantuccio area.
Although in German this extract from the "Kompass" company might give you an idea
The path from the Winkel / Cantuccio is the Franziskusweg. You follow this to the waterfall. Where the route crosses the road is the Gasthof Toblhof (Guesthouse/restaurant) on the main road.
Just to add if you use http://www.sii.bz.it/en and click on timetables as pdf scroll down to the No 452 & 453
This service runs between Sands and Rein/Acereto stopping at the Toblhof: However they are currentyl winter timetables up until 4th April.