They don’t treat launch water, it runs off into the wetlands through open ditches. The SRBs that the Shuttle and SLS use are 100-ton bricks of perchlorates that contaminate and acidify water for miles every time there’s a launch, so treating the direct runoff is deck chairs on the Titanic. Kennedy Space Center is already a Superfund site, so they focus on things like underwater fencing to stop KSC fish full of teflon and cadmium from being eaten by normal fish.