Percussion drilling is a drilling technique in which a drill bit attached to rope or cable is repeatedly raised and lowered, impacting soil and rock and making the hole deeper. Frequently used to drill wells or during mineral prospecting activities, percussion drilling has been used for thousands of years and is adaptable to whatever technology is available. Percussion drills may be simple apparatuses consisting of a heavy drill bit and a rope, and operated by hand. Modern percussion drilling may also be called cable drilling and uses an engine and cable to drill holes that may be hundreds of feet deep.

One use of percussion drilling is in third-world countries as a cheap and reliable way to drill water wells. Equipment is easy to build, transport, and simple to use. Percussion drills introduce less contamination than conventional hand drilling methods. This technique can drill a narrower and deeper hole than hand drilling through many different types of soil and rock.

If the substance being drilled through is sturdy enough, drilling can continue until water is reached. If drilling occurs in loose soil or sand, a pipe may need to be inserted to keep walls from collapsing. After the well is deep enough, permanent casing is installed, too.

There are some drawbacks to percussion drilling. It is slow and requires heavy equipment. Some drill bits may be very large and heavy if drilling through certain types of resistant rock. Unless an engine is available, percussion drilling can be very labor intensive. Also, water must be added to the hole to make dry material easier to penetrate and a bailer used to remove accumulated mud and debris.

Modern cable drills use larger drill bits and steel cables. Drill bits may weigh as much as a ton and are powered by engines. Holes dug can vary in depth from less than 100 feet to thousands of feet. The deepest hole ever dug by this method was 11,145 feet in 1953.

For many years, percussion drilling was the primary method used to drill oil and geothermal wells. In recent years, rotary drills have become more common because they are quicker and are not limited to vertical holes, as percussion cable drills are. Percussion drills still have a place, however, in some geothermal production zones.

Percussion drilling technology has even been adapted to laser drills. Gas turbine engine manufacturers have used concentrated laser beams to drill holes less than one millimeter in diameter in turbine engine components. These holes are used to cool the engines and prevent overheating.