I created this thread so you all know how much water to use to dissolve benzodiazepines for injection. It's come to my attention people are still going to try shooting benzos, even those that aren't as feasible to inject in water only, so I want to help you all instead of leaving you all in the dark.
Hopefully these statistics should reflect water solubility at a pH of 7. If the pH fluctuates, the solubility may increase or decrease. You don't want to inject highly acidic or basic water, so I'm going to list statistics for pH of 7.
Alprazolam (Xanax) - 0.04 mg/mL (source)
Chlordiazepoxide (Librium) - 2 mg/mL (source)
Clonazepam (Klonopin) - < 0.1 mg/mL (source)
Diazepam (Valium) - 0.05 mg/mL (source)
Estazolam (ProSom) - 0.0015 mg/mL (source)
Flurazepam (Dalmane) - 500 mg/mL (source)
Loprazolam (Dormonoct) - 10mg/mL (source)
Lorazepam (Ativan) - 0.08 mg/mL (source)
Midazolam (Dormicum) - 0.024 mg/mL (source)
Oxazepam (Serax) - 0.179 mg/mL (source)
Temazepam (Restoril) - 0.164 mg/mL (source)
Triazolam (Halcion) - 0.00453 mg/mL (source)
Zolpidem (Ambien) - 23 mg/mL (source)
Zopiclone (Imovane) - 0.151 mg/mL at 25°C ** (source)
As you can see, only flurazepam and midazolam are feasible for shooting in just water. Loprazolam is too, but I was unable to find information on it. If you can cite a source, please submit it so I can add it to this list. Any information on any other related drugs, or any other benzos of any kind are welcome as well.
For most other benzodiazepines, without having to use a vastly huge volume of water, you would want to use a safe, USP grade solvent, or you would want to avoid taking it IV.
There are many reasons not to inject benzodiazepines. For one, they seem to work better orally. Other than triazolam and midazolam, most benzodiazepines have at least 80% oral BA. Flurazepam is the one closest to 80%, and even then, I would personally prefer taking flurazepam orally over IV. Most benzodiazepines are going to last longer when taken orally. For the most part, they don't take too long to kick in either.
Furthermore, not filtering IV solutions with benzodiazepines with a micron filter may lead to complications, or at least be bad for your lungs and or other bodily organs. Please read the Case Studies thread for more about this.
** 25°C = 77°F