1 Just a note to verify that last statement, Valium stays in your system a LONG time, after taking just 2-3 over a 2 day period, i tested posted for it 1.5-2 wks later. 2  And I am a 35 yr old v. active male, and normally drink lots of fluids...so be careful if you have a test coming up.ood luck. 1  Just a note to verify that last statement, Valium stays in your system a LONG time, after taking just 2-3 over a 2 day period, i tested posted for it 1.5-2 wks later. 2  And I am a 35 yr old v. active male, and normally drink lots of fluids...so be careful if you have a test coming up.