because it can become a breeding growund for bacteria, parasites, and everything else you do not want for you herb.
what kind of stagnant water are you talking about? like water in an open container or closed? and for how long would the water be sitting out?
i woulden`t use swamp water, unless it was purified some kind of way, and then thats not guarenteed. what would be the reason to use swamp water? privact concerns about bringing water to your crop? i would try to get some kind of containers with water to your crop, and if you can`t and have to use the swamp water i would try to boil it first or use purification tablets or something.
stagnant water is anaerobic.... in other words, it has a very low dissolved oxygen content.
mj gets most of its oxygen from dissovled oxygen in water taken in by the roots.
stagnant water also tends to be full of bacteria, fungi, insect larvae, and other nasty parasites; and swamp water will have a very low ph as well, from all the rotting veg material.
whats more important is, where is this water coming from?
if its ground water seeping to the surface, it might be better than what you could buy in the stores...... if its swamp water draining out to a lower elevation point, its prolly going to be some nasty shit
i would try to get your water from the stream, faster moving water the better. but slow moving water might be okay, i hade to use water from a slow moveing stream in a previous crop and it worked fine. But you should always test the p.h. of the water first. Or you can always catch the rain too and use that, but i would try to use the stream water, if its okay/