represents the application of chemicals on or into the soil in a certain process
(in mass/time). This model is the simplest, least detailed method to estimate the
grey water footprint in the case of diffuse pollution; so it is recommended only
as the default method, to be used if time does not allow a more detailed study.
Higher levels of detail are possible; it is proposed to distinguish three levels of
detail: from Tier 1 (the default method) to Tier 3 (the most detailed method). In
Tiers 2 and 3, more specific data and advanced methods are to be used (Box 3.7