Utilizing an optimized process that combines gentle cell lysis with a tunable fragment length generation followed by precipitation of the extracted DNA onto the surface of large glass beads, the prep proceeds rapidly and utilizes standard laboratory equipment. DNA size ranges from 50-250 kb for the standard protocol and into the Mb range when the lowest agitation speeds are used. Purified DNA is recovered in high yield with excellent purity, including nearly complete removal of RNA. For cells, the process time is only 30 min, while blood samples require erythrocyte lysis and are processed in 60 min. Purity ratios of 1.80-1.90 and 2.2-2.5 (A260/A280 and A260/A230, respectively), are easily and reproducibly achievable, and purified HMW DNA is suitable for a variety of downstream applications including long-read sequencing (Oxford Nanopore Technologies and Pacific Biosciences), optical mapping (Bionano Genomics), and linked-read genome assembly.