Bath led 38-10 at the interval, with Tom Dunn, Tom Homer, Robbie Fruean, Kahn Fotuali'i and Ford all going over.
Samoan Fotuali'i crossed for his second try, as Rokoduguni and Chris Cook also scored at Ashton Gate for the visitors.
Tom Varndell, Rhodri Williams and Jack Tovey went over for Bristol, but they remain third in the pool.
Fly-half Ford, who has been strongly linked with a move to Premiership rivals Sale at the end of the season, contributed 20 points as Bath did the damage in the first half.
Fotuali'i's double on return from an eye injury was another plus, with Todd Blackadder's team five points clear at the top of their European Challenge Cup group ahead of Cardiff Blues' trip to French Top 14 side Pau on Saturday.
Bristol: Arscott; Wallace, Palamo, Pisi, Varndell; Searle, Williams; Traynor, Crumpton, Ford-Robinson, Phillips, Glynn, Lam, Robinson (capt), Eadie.
Replacements: Jones, Bevington, Cortes, Nemsadze, Joyce, Cliff, Jarvis, Tovey.
Bath: Homer; Rokoduguni, Joseph, Fruean, Watson; Ford (co-capt), Fotuali'i; Catt, Dunn, Lahiff, Ewels, Stooke, Mercer, Louw (co-capt), Grant.
Replacements: Walker, Obano, Palma-Newport, Douglas, Mercer, Cook, Priestland, Tapuai.
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England internationals George Ford and Semesa Rokoduguni were among the try-scorers as Bath thrashed local rivals Bristol to close in on qualification.