Celine Dion must have some serious deposits to flush -- she's passing enough water in a Florida house to fill a 50-gallon bathtub ... every four minutes.

Here's how Celine's all wet: Utility records in South Florida show that a property owned by her company Renlec Management used 6.5 millllllion gallons of H20 last year. As the Palm Beach Post points out, most residential users in the same county use around 100,000 gallons of water per year -- so Celine uses about 65 times as much water as the little guy. (Her reps had no comment.)

And Dion isn't the only Martin County celeb whose water waste will go on, and on, and on: Tiger Woods, who's building a house on Jupiter Island, used about 300K gallons a month, mostly for landscaping and tree-planting, according to his peeps.