I grew 2 plants from bagseed and watered them from the time they were about 5 weeks old till harvest with bong water. My analysis? It DOES help. I went from shitty bagseed to something I actually enjoyed smoking. Don't turn something down until you've at least tried it.
THC may not be water soluble, but, if you look in your bong water, there are bits of weed in the water, unburnt, still green even. Saying the only thing in water is ash and carcinogens is kind of wrong. The water DOESN'T contain THC, BUT! The bits of weed in the water DO! My thoughts, if you want to pour bong water on your plants, go ahead. Unless you spent 30 bucks on a seed, you haven't anything to lose. If it works for you, it works. If not, try something else. It worked for me though. p.s.: I know this post is almost 6 years old, but this subject is something I chose to defend, due to my experience with it. Thanks all. =]
Actually, the plants would most likely like this. Ash has a very potent fertilisation effect. Just look at the forests already growing around Mount St. Helens.
There is so much misinformation in this thread that it's a little sad. I just have to say that bong water does have some THC. I wouldn't want to water my plants with it, but it DOES have THC the same way resin builds up on the sides of your pipe, the resin builds up on the inside of the bong and melts into the water. All that ash and resin puts some THC into the water. I agree with the person that said ashes can be a fertilizer. That would be the only benefit of watering with bong water. But I would still rather stick with reg nutes.