Why can't you be buried without a coffin?

Answer 1

Within hours after death, the body begins to decompose naturally. Most US States enacted laws about whether a body must be embalmed or not. If embalmed, the natural decomposition is slowed but not completely stopped.

Burial laws also differ from State to State and Country to Country. In most US states, a body is buried in a coffin or ashes in an urn. However, a coffin can often be: a cardboard box, a pine box, or a more elaborate coffin usually made of steel on the outside. In addition, many States require a burial vault. The vault is a 3-sided concrete structure into which the coffin is lowered; the vault lines the inside of the grave.

Coffins and burial vaults act as a barrier between decomposing flesh, which contains fluids, and the ground and water table. As such, coffins and vaults protect the soil and ground water from human contamination. Contamination would create a public health risk.

As well, weather, rain, etc. can cause above-ground erosion. Caskets prior to the 1900s were always made of wood, mostly just a wooden box. The tops and sides of wood caskets eventually cave inward due to pressure from the soil. With weather, erosion, and caskets falling apart, people can often see deep depressions in the ground in the shape of a grave. The depressions can be several inches or more down. The weathering effects are much reduced with using a metal coffin and concrete vault because these do not cave inward as easily, and take hundreds of years to deteriorate.

In some areas (ex. southern states, or near rivers), like floodplains, burial locations may be prone to flooding and erosion. These can uncover coffins, whether intact or broken. So these cemeteries often require certain types of coffins, or require above-ground vaults, or require burial in a mausoleum -- a small building above ground in which coffins are slid into pre-made slots in cement walls, then cemented into the slot on the front (feet) side.