To quote from British Listed Buildings. co. uk (mainly because I wouldn’t know where to start describing this rather unusual Grade II listed structure):
“Water tower for Great Western Works. 1870. Cast iron. Round storey stanchions. 3 bays by 3 bays, in 4 lifts, all diagonally braced and with cast iron girders with interlaced circles at each lift. Central bay on plan with timber faced shaft. Grillage platform for water tanks at top, the tanks a replacement of 1979-80. The water tower forms an important landmark“.
Now it stand in the grounds of the University Technical College and is, in my opinion, the best preserved landmark relating to the former Great Western Works on Bristol Street.