Pump and filter for filling fresh water tank

My dad wan an analytical chemist and kept a big plastic jar of Mercury on the shelf. As a kid I played with the 'noble metal' that is liquid at room temperature myself and we used to beat on the asbestos pipe wrap in school to make it 'snow' and I'm still here too. I worked many years a a paint shop foreman for an electronics cabinet maker and the routine coating, besides electro deposition coating was catalyized polyurethane which is loaded with isocynates... I'm still kicking....and I smoke too.

I have no idea how you would test for micro organisms. I would say change the filters when instructed and call it good (other than investing in a microscope and coating a slide with the water and looking...