Are you planning ahead to treat problems?
Doesnt really matter how much water you used, as long as you get the dosage right, and you can get it down the throat usually via catheter.
If thats the right dosage, itd be 50-100 mg/kg every day for 7 days
Youd just have to see how many mg of drug you have per gram of powder, and then dispense the right amount according to the animals weight.
It takes a scale that is able to read in tenths of grams usually.