It is EXTREEMLY RARE for any employment test to be observed. Les than 1/10 of 1% are. SUbstituting a clean sample, at the proper temp, works 100% of the time. Synthetic urines are 100% effective and some are premixd and ready to just heat and pour. Read the substitution guidelines linked to in my signature, do some practice with a bottle of water and report back with any questions you have. As far as a substitute sample is concerned, my favorite is Quick Fix. I face random testing every day at work, as a CDL holder, so I never go to work with out a bottle of QF. Here is a link to it. http://www.urineluck.com/products/7.html
Hope that helps.
N2