Weedspray wash into Effluent Pond
Correct @MattD2. You can see why I didn't pass math! So many decimal points.
So lets try again
10ml of herbicide coming out of the container = 100mgs. If 36% of this is glyphosate we then have 36mg's of poison
We've got 36mg going into our 1 litre sprayer. And we then spray 99% of our brew or 35.64mg's onto weeds.
This leaves us with 0.36mg to dispose of with our triple rinse
Rinse 1 we tip 99% into the effluent pond so there goes 0.3564mg. Leaving us with 0.0036mg
Rinse 2 we tip 99% into the effluent pond and there goes another 0.003564mg. Leaving us with 0.000036
And third rinse we get rid of the lot so the final bit gets tipped into the pond.
So in the end, for 1 liter of spray we have disposed of 0.36mg in 3 litres of water that now heads to the effluent pond. Or 0.12mg a liter which is a smidge above the danger level - before it hits further dilution.
That my homework done. I hope I pass. But I expect a fail! (And its why I'm not an accountant)
@robb - Back in the day Glyphosate was my weedkiller of choice. I went through hundreds of litres of the stuff. Killed the weeds but not the good micro critters in the soil. Its good stuff for humans and plant - providing you don't drink it straight out of the container. The one I'd be watching out for around the home for humans and plans is Dicamba - now that can be pretty nasty to non target plants.
And if you have broad leaf at home - a sprinkle of salt will do the job.