Well, I've written a few companys... One guy said it stays as long as urine, but another says it's only 3 hours, 4 days MAX... Who knows what to believe... I'll probalby just end up buying this Aqua Clean system... Oh well... I'd rather smoke weed than not for the next few weeks, I've torchered myself long enough (3 weeks), so I have it coming tonight... YAY!!!!!