As it relates to breakin down/preppin' pharms or street drugs,"treatin'em t'warshin' n'filtrn'n'stuff" having 30 days worth at once was exceedingly rare (excluding bupe, cannabis) tho obviously the dose makes all the difference. I dont partake now but if i did i would find the formulations arent preferable to even the last choice of 4 manufacturers as lil as 10ish yrs ago. The availability/reliability is appalling, prices have more then tripled on MSContin and various Oxycodone formulations from Perc to Oxy IR/Roxi. Back in the day: Gets call from a couple he knows lookin for them pins and needles, i ride to ole boys house with their 60 for 2 Grey Ghost 100's, i throw 20 in and walk away with two, last time i heard of ABG 100 around me in any direction. ... 65$. But I digress.
If you keep the pulverized pill(s) mass dry, get your water cold enough, add a small sprinkle of salt, carefully fill then assemble mixing syringe, diligently shaking the suspension before pushing thru filter. It wont be "thick" at 50mg/1 ml if you have good pills to work with, if its some shitty 15s or 30s requiring more water/other solvents one would expect a lower concentration.
The method works killer for single doses but i have had success dozens of times with making "easier to fly under the radar at home around the family" runs of various pain pills, never micron filtered, never used bacteriostatic water. I never experienced any problems/complications with bacteria, gelling, evaporation, falling out of solution, no cotton fever from this method, when on sub scrip i would break down 2.5 8mg tabs, filter and end up with 1mg/.1ml, 20 days worth. Ive done the same with 3 blue Endo 100mg Morph -> 5cc = 60mg/ml, had the same vial over a long weekend excursion, no sleep, no refrigeration, no problem.
LET ME BE CLEAR, anything relating to risking sepsis/cotton fever by ignoring better judgement. By using inferior water unsuitable to prevent bacterial growth, even to store it in a vial for only a few hrs, is extremely irresponsible and dangerous. If one has the means to procure drugs for 30 days, one can certainly afford bac. water, microns, new vials, ect.