I overwinter water lilies in a kiddy pool, where they tend to go semi dormant, even though they are artificially lit, and get some indirect sun.
Their root systems are fairly large, and the pots they require are about 18" in diameter and 12" to 15" deep.
in summer they almost totally cover the pond outdoors
Below is a shot from last week, the pond is about 4'wide and 12' long.
I have also tried water hyacinth inside, but as Joe said, generally does very poorly, although in a window with full sun (the window box above has a southern exposure and has a glass top), it can do well for a while, but usually dies back drastically, toward winters end.