How long will cheap oil transfer pump survive pumping water?

Thanks for the thoughts. Great idea about a bilge pump. Unfortunately no one local has one in stock. Yes, I did think about just replenishing as it loses but I was concerned about introducing cold water into the system with the engine hot. I hadn't considered the pump losing prime, but yes, my intention is to switch off and on with a toggle as needed. Good idea on having a backup. I do have some Right Stuff but I can't tell exactly where the leak originates and I'm trying not to do anything irreversible on the chance that the core is repairable. New is available but $550. I guess the cool part is this is exactly the kind of rigging my grandpa would have done but he would probably farm like that for 5 years.