It could just be a bug I am experiencing I will wait for the official 1.8 release because it could just be because of the fact that it is a snapshot
Even when I leave the ID blank it doesn't work it still spawns then despawns
I summoned it like you said /summon FallingSand ~ ~ ~ {Time:60,TileID:minecraft:water}
What is weird is that this didn't start happening until I updated java to java 7 update 45