French drain

French drains are primarily used to prevent ground and surface water from penetrating or damaging building foundations and as an alternative to open ditches or storm sewers for streets and highways.

The earliest forms of French drains were simple ditches that were pitched from a high area to a lower one and filled with gravel.

These may have been invented in France,[3] but Henry Flagg French (1813–1885) of Concord, Massachusetts, a lawyer and Assistant U.S. Treasury Secretary, described and popularized them[4] in Farm Drainage (1859).

To prevent clogging, the size of the gravel varied from coarse in the center to fine on the outside and was selected contingent on the gradation of the surrounding soil.

Modern French drain systems are made of perforated pipe, for example weeping tile surrounded by sand or gravel, and geotextile or landscaping textile.

Depending on the expected level and volume of rainwater or runoff, French drains can be widened or also fitted on two or three underground drainpipes.

Filters are made from permeable materials, typically non-woven fabric, may include sand and gravel, placed around the drainage pipe or envelope to restrict migration ofnon-colloidal particles[clarification needed] from the surrounding soils.

Clarified sewage from the septic tank is fed into weeping tiles buried shallowly in the drain field.