Water purification pills do not work, but large amount of pure water does. You have 2 basic choices.
1. continue to abstain from smoking. Read the dilution guidelines linked to in my signature. Load up on Creatine and with 7 days clean, you should pass with flying colors.

2. continue to smoke and substitute a clean sample. Employment test are not observed, so subbing a clean sample, after practicing it, is a piece of cake. Substitution guidelines are also linked to in my signature.

Hope that helps.
N2