As nouns the difference between drainage and diversion
is that drainage is a natural or artificial removal of surface and sub-surface water from a given area while diversion is a tactic used to draw attention away from the real threat or action.
As nouns the difference between drainage and filtration
is that drainage is while filtration is the act or process of filtering; the mechanical separation of a liquid from the undissolved particles floating in it.
As nouns the difference between sanitation and drainage
is that sanitation is the hygienic disposal or recycling of waste while drainage is a natural or artificial removal of surface and sub-surface water from a given area.