Items do not enter hoppers when water flows to them, but not over them

I'm building a simple layered farm where the water flows the items into a line of hoppers, which is simple enough, but seemingly because I made the water flow stop RIGHT at the hopper line, the items DO NOT enter the hoppers, or flow onto ANY other block I set down; it's either that they stop IN the flowing water, as if there's a block in their path, or they drop like a waterfall into a hole; no block; air