You can buy these pressurized cans or bottles at drug stores. This is a convenient packaging of wound wash that can be kept in your emergency kit for occasional use.
In our vet practice, we use a hand sprayer to which we add isotonic electrolytes (saline). The idea is that by using saline (which is approximately the same solute concentration as blood and tissue), there is no drying or hydrating effect to the tissues.
When pure water is used to flush a wound, the tissues become over-hydrated. This can be damaging to cells and may reduce healing. That said, in the absence of saline, water works fine.