Lots of folks paint their pvc with stuff like Krylon Fusion spray paint. Not sure about leaching but I would make sure you let the paint cure fully before using in water. I would not paint anything that will take some abuse as it will for sure flake and peel and look way uglier than if you left it plain white.
Also, if you wish to splurge, bulkreefsupply.com and others do sell color pvc.