You can use a sand filter or ...

You can use a sand filter or multimedia filter to remove turbidity from the source water.  But the filter media will quickly foul if the water is very muddy.  The best thing to do is eliminate the problem at the source.  You may be able to rehabilitate the well.  A good well driller could give you a better idea what you could do.  Perhaps pumping the well for a long period woul clear it up.  Maybe the well needs to be drilled deeper and then sealed off with bentonite.  Maybe a new well is needed.  Running a camera down the well may provide more details of the well failure.  For the camera to be of any use the well would have to be left idle so the water column could settle and be clear enough to see through.