Big Brother's controversial eviction was followed by its worst five-city audience figure and lowest placing in the TV ratings this season.
The Nine Network reality series was the 17th most watched show on Wednesday with 618,000 viewers, according to OzTAM's overnight ratings.
It was beaten in its timeslot by the Seven Network's Criminal Minds (868,000) and by ABC comedy series Utopia (620,000).
The previous lowest five-city (Sydney, Melbourne, Brisbane, Adelaide and Perth) result was last Wednesday when it was 14th with 634,000 viewers.
The 11th season of Big Brother launched 17 days ago with 1.067 million viewers, the only time it has topped seven figures.
The second episode dipped to 924,000 and it's been downhill ever since.
There have been a couple of episodes which have come in well below 500,000 viewers but that was on nights it did not air in all five capital cities due to Nine's NRL commitments.
The latest ratings follow Tuesday night's controversial eviction when the housemates had to choose between Gemma and Jake to stay.
It caused a massive social media storm and was labelled "mobbing" by a bullying researcher.
The ratings will be of some concern for Nine although the network did take out the first three places in the rankings.
The Block Glasshouse won the night with 1.185 million viewers, followed by Nine News (1.140 million) and Nine News 6.30pm (1.106 million).
The reunion episode of Network Ten's dating series The Bachelor was 14th with 640,000 viewers.
Most watched shows on Wednesday
1. The Block Glasshouse (Nine) - 1.185 million
2. Nine News (Nine) - 1.140 million
3. Nine News 6.30pm (Nine) - 1.106 million
4. Seven News (Seven) - 1.013 million
5. A Current Affair (Nine) - 996,000
6. The Force - Behind The Line (Seven) - 972,000
7. Seven News/Today Tonight (Seven) - 970,000
8. Home And Away (Seven) - 893,000
9. Border Security - Australia's Front Line (Seven) - 876,000
10. Criminal Minds (Seven) - 868,000
14. The Bachelor (Ten) - 640,000
16. Utopia (ABC1) - 620,000
17. Big Brother (Nine) - 618,000
- Source OzTAM