no please no colored water please whats the point? last week i filled my water bong with cheap ron. it-was-good.
"Necessary? is it necessary to drink my own urine? No, but it's sterile and I like the taste!" Seriously though the OP never asked what was necessary. Adding food coloring is just an aesthetic. People use it with clear bongs because its better to look at than nasty yellow bong water. Just be sure to rinse it out with hot water when your done, or just use it in your ashcatcher.