Blues, who made ten changes from last weekend’s European campaign, fronted up in high winds and relentless rain in the first half as, despite home tries from Alafoti Fa’osiliva and Micky Young, the visitors only trailed 12-6 at the break.
Former Blues man Gavin Henson climbed off the bench to score for the hosts as they took control in the second period and a late try from Guy Mercer wrapped up the bonus point.
However, Dan Fish scored a deserved late try for Blues and it was a day of positives as many young players went toe-to-toe with a Bath outfit that contained 10 full internationals in the match day squad.
An encouraging 60-minute return for Welsh international centre Owen Williams – who made numerous line breaks - was also a major plus for the visitors in the West Country.
A penalty at the first scrum of the game to Blues, as Benoit Bourrust hit well, gave Simon Humberstone a first shot at goal that he drilled over as the visitors started promisingly.
Bath turned down a shot at posts themselves, as Blues were penalised for pulling down a driving lineout, just minutes later. The rolling maul was formed again and this time the home side ploughed over with the try awarded to back row Fa’osiliva.
Rory Watts-Jones turned over ball in the tackle while Blues showed some clever lines and attacking edge to break from the halfway line until Tom Williams was shunted into touch as he took an inside pass from Fish.
Owen Williams and Chris Czekaj also showed nice interplay to look to break the Bath rearguard. However, as play was spun wide a knock-on in midfield stopped the play. Watts-Jones then charged down a Heathcote kick, but it ran dead and not for Humberstone.
Blues were dominating territory in the opening 20 minutes with the wind behind their backs and after Owen Williams cut a powerful line the visitors won another penalty near halfway. Humberstone hit the kick well, but the strong wind saw the ball pull wide of upright.
Battering-ram centre Banahan finally broke up the left and Blues did well to maintain their defense with a quick tackles from the back three but, with the England man offloading to Biggs, Bath made further yards before winning a penalty.
Blues defensive efforts were rendered futile as Young powered through, crossing the whitewash to add a further try for the home side. Picking the ball from the lineout he ran circles around the wall of pink to cross under the posts with Heathcote added the conversion.
With the Blues on the back foot, Bath looked to make it a hat trick of tries with Samoan back row Fa’osiliva thundering down the middle. The young Blues showed great reserve, forcing him down outside of the twenty-two with Hamilton taking him round the ankles.
Blues were offered a lifeline to narrow the gap before the break when Bath conceded a penalty and Humberstone popped the ball straight through the middle of the uprights despite the advancing storm clouds overhead.
Matt Garvey looked to upset the Blues in the closing minutes, barging through tackles. But Blues held firm under huge pressure in the final few seconds of the half as they trailed 12-6 at the interval.
Owen Williams produced a trademark run at the start of the second half as he powered down the middle and handing off men. The visitors looked wide for a breakthrough, but Bath held firm and finally turned over the ball to kick clear.
Bath enjoyed a spell of sustained pressure on the visiting line and, with Blues a man down as Lewis Jones had treatment by the sidelines for a nasty cut, the ball finally found the hands of Henson to touch down.
Replacement Ben Roach made hard yards on debut, after coming on for Watts-Jones, while Henson’s stray pass was picked off by Bourrust and quick hands found Czekaj.
Bath’s power up front was causing problems as they shunted a visiting scrum backwards and David Sisi peeled off as they hunted the crucial try bonus point.
The game entered the final ten minutes with Blues still refusing to give an inch as they continued to rattle into tackles with Tom Biggs stopped in full flight by a combination of Ellis Jenkins and Tom Davies.
A brilliant team move saw Owen Jenkins cut inside men off Humberstone’s pass and feed namesake Ellis as Blues threatened a deserved score as they made 40 metres.
Home centre Ollie Devoto was yellow carded as Bath desperately tried to stop the pressure as Hewitt was bundled towards the whitewash.
The hosts wrapped up the bonus point two minutes from time as a driving lineout was shunted over and Mercer popped up with the ball. Heathcote hit the post with a low kick.
Blues hit back with a well worked score in the final minute as Gavin Evans broke the line and fed Fish who dummied the final pass and raced over.
06m Humberstone p 0-3
08m Fa’osiliva t 5-3
29m Young t Heathcote c 12-3
38m Humberstone p 12-6
49m Henson t Heathcote c 19-6
78m Mercer t 24-6
79m Fish t Humberstone c 24-13
Cardiff Blues: 15 Dan Fish, 14 Tom Williams (Jenkins 67), 13 Owen Williams (Hewitt 65), 12 Dafydd Hewitt, 11 Chris Czekaj, 10 Simon Humberstone, 9 Lewis Jones (Lloyd Williams 52-59, 77); 1 Tom Davies (Smout 77), 2 Rhys Williams, 3 Benoit Bourrust (Lewis 77), 4 Chris Dicomidis, 5 James Down (Normandale 77), 6 Rory Watts-Jones (Roach 40), 7 Ellis Jenkins, 8 Luke Hamilton.
Replacements: 16 Kristian Dacey, 17 Lewis Smout, 18 Callum Lewis, 19 Miles Normandale, 20 Ben Roach, 21 Lloyd Williams, 22 Gavin Evans, 23 Owen Jenkins