Bristol will be in the Second Division next season unless English rugby's rulers offer them a possible escape route through relegation play-offs.
Fellow strugglers London Irish condemned Bristol to a 10th successive Allied Dunbar Premiership defeat, meaning automatic relegation if the play-off option is scrapped.
The Rugby Football Union and England's top clubs have still to hammer out an agreement. No announcement is expected before May 1st, leaving Bristol in limbo.
The fallen West Country giants are among only six English teams never to relinquish top-flight status since leagues were introduced in 1987.
But London Irish, who deservedly closed the gap to one point behind 10th-placed fallen champions Wasps, compounded their misery, prevailing despite dreadful conditions of driving rain and a biting wind.
It was the Exiles' fourth league win from five starts under coach Dick Best, this latest triumph secured through tries from their Western Samoan number eight Issac Feaunati and centre Sean Burns. Wing Niall Woods converted both, and also kicked a penalty.
Bristol rarely threatened. Their only crumb of comfort was an opportunist 69th minute touchdown from centre Simon Martin.
Irish, who visit Northampton on Wednesday night, still have five league games remaining and could conceivably overhaul Wasps by moving out of the danger zone.
But Best will not have been satisfied with an error strewn display. Feaunati crossed from a 21st minute line-out, Woods landing the difficult conversion, and when the wing struck a 46th minute penalty it gave Irish a decisive 10point advantage.
Bristol: Hull; Tiueti, Martin, Maggs, Lewsey; Baber, R Jones; Poole, Landreau, Fullman, Charron, Devergie, Short, Rollitt, Brownrigg.
London Irish: C O'Shea; J Bishop, B Venter, S Burns, N Wood; D Humphreys, P Richards; L Mooney, R Kellam, J McLaughlin, N Harvey, M O'Kelly, K Spicer, I Feaunati, K Dawson.