Pour a gallon of Clorox directly into the well and run a hose from the pressure tank back into the well. Turn on the valve at the pressure tank and let the treated water circulate between the pressure tank and the top of the well. This will clean the entire well casing. After 15-20 minutes, turn on ALL the spigots in the house and let run until you smell chlorine (Clorox). Turn all the spigots off, including the hose back to the well and let everything sit (nothing running) for about an hour. After about an hour, turn on the hose from the pressure tank and run it into the woods, street, any place EXCEPT your septic system. Run it until you don't smell Clorox, an hour at the least. At this time the well and pressure tank should be all clear water. Turn on all the other spigots and run until the Clorox smell is gone. Don't worry about the dishwasher but be sure the first load in the clothes washer is white T shirts, socks etc. After about a week, give your septic system a good dose of Ridex to replace the bacteria that you just killed.
Filters are OK but why would anyone want the bacteria in the first place?