Years later I've tried many solutions and graduated to wanting a really good filter that also LOOKS good in my home and makes it easy to drink water often. Because I rent I haven't yet opted for an undercounter system at home (preferable), but we have put one in the office, and it works really well.
Different types of tests call for different detection times. Oxycodone is detectable in blood tests for roughly 24 hours, in saliva tests for 1-4 days, urine tests 3-4 days and hair tests up to 90 days. This is backed up by findings done in a 2014 study by Ron R. Flegal for SAMSHA.
If they choose to use HPLC or GC/MS for urine screening, it would be detectable for approximately 30 days after the last use. A standard urine test however would only detect oxymorphone within 5-7 days of the last use. However, hair tests can detect oxymorphone for about 90 days after the last use. It is important to note that companies rarely, if ever, use HPLC or GC/MS screening due to the cost.