How long would a submersible sump pump last when it is submerged in water at all time?
I assume the main cause of failure is rust/corrosion of metalic parts.
Is there any sump pump designed so that metallic parts stays dry except when it is pumping?
In theory, only the water sensor and the inlet hose need to be submerged at all times. The rest of the pump could be located away from the water.
The reason for asking is I'm getting bids for crawlspace waterproofing (more like water draining). Most contractors by default offer a french drain + sump pump system. But there is a drainage pipe already in the crawlspace, possibly connected to the storm drain, and possibly partially clogged -- that's why I have wet crawlspace. If the pump won't last more than 10 years, I might insist on fixing the existing drain so that the system works purely on gravity.