This need not be accurate to 600- 1000 times. Speaking of one milliliter, because you use powder approximation, so take 1g as 1ml (the density of these organic drugs is mostly around 1g/cm 3). You can also use the bottle cap of coke. The flat powder of 1g bottle cap is about 7g. .
In this case, 7 grams of water is 1 1200 liters (you can only improve your measurement and reduce the relative error without high-precision measuring equipment). If you don't know the answer, you can continue to ask me if I am satisfied or not.