Capsaicin is not soluble in water, and even large volumes of water will not wash it off, only dilute it. In general, victims are encouraged to blink vigorously in order to encourage tears, which will help flush the irritant from the eyes.
A study of five often-recommended treatments for skin pain (Maalox, 2% lidocaine gel, baby shampoo, milk, or water) concluded that: "...there was no significant difference in pain relief provided by five different treatment regimens. Time after exposure appeared to be the best predictor for a decrease in pain...".
Many ambulance services and emergency departments carry saline to remove the spray. Some of the OC and CS will remain in the respiratory system, but a recovery of vision and the coordination of the eyes can be expected within 7 to 15 minutes.
Some "triple-action" pepper sprays also contain "tear gas" (CS gas), which can be neutralized with sodium metabisulfite (Campden tablets), though it is not for use on a person, only for area clean up.