Currently you're only destroying items dumped on 3 of the Gleba water tiles. Might be intentional I guess.
I have a list here of Gleba tiles that give you water if you put an offshore pump on them: https://github.com/StephenBarnes/LegendarySpaceAge/blob/master/code/data/filtration.lua#L219

Also missing the "brash-ice" tile on Aquilo. If you want all tiles with fluid (all tiles that allow offshore pumps) to allow dumping then instead of making a list of all of them you can use this instead:

for _, tile in pairs(data.raw.tile) do
    if tile.fluid ~= nil then
        tile.destroys_dropped_items = true
    end
end

Edit: actually remembered you have separate settings for each planet so never mind, that won't work.