When drilling blind holes in iron or steel, fine metal bits usually fall into the hole. To remove them, you can use a strong magnet and a soft iron or steel rod that is smaller in diameter than the hole. Push the rod to the hole bottom, then press the magnet to its upper end. Keeping the magnet to the rod, pull it out of the hole and brush away the bits of metal. Repeat until all of the metal bits are removed.
If the sewer line or drain line for a home you are buying crosses another property, make sure there is a recorded easement that will permit access to maintain or repair it. Without an easement, you would have to hope for your neighbor’s cooperation, but you would not be able to count on it.