Equation (1) also abstracts from capital depreciation, taxes/subsidies on intermediate inputs, and exogenous changes in efficiency. All of these considerations are typically also included in global CGE analyses - in particular those based on the GTAP framework. The subscripts i refer to produced commodities, of which there are N in total. As shown below, in most CGE models, this is where municipal water shows up since the municipal water supply is provided by a public utility using scarce resources.