A catheter based drug delivery system for minimally invasive delivery of treatment drugs into a bladder wall. The catheter system can include a delivery tip for deforming the bladder wall before forming jets of drug solution that penetrate the bladder wall for needleless delivery of the treatment drugs directly to the diseased tissue. The delivery tip can also have graduated markings for providing visual indicators of the relative depth of the delivery tip in the bladder wall and the alignment of the formed jets with the particular layers of the bladder wall.