Inert waste is waste that does not undergo any significant physical, chemical or biological modification : Inert waste does not decompose, burn or produce any other physical or chemical reaction, is not biodegradable and does not deteriorate other materials with which it comes into contact in a way that could lead to environmental pollution or harm human health.

In practice, and according to the modified Grand-Ducal regulation of 24 February 2003 concerning the landfill of waste, waste that can be considered inert waste is

- made up almost entirely of natural soil and rock resulting from their extraction during construction work;

- resulting from road works and of a mineral nature;

- from construction, renovation or demolition sites, which are mainly of a mineral nature. One condition is that the inert waste is not contaminated by hazardous substances or other potential nuisance generators.