A concept used in water budget–based rates to define tiers or blocks. It is usually calculated by estimating the average annual amount of water used by a household based on past water bills and household characteristics, or the average over the course of the winter, which typically excludes outdoor use. Those totals can determine how much water is required for basic needs and how much water use is excessive or wasteful. Generally, water budget–based rates are higher for consumption that exceeds AWC than for water use that is less than or equal to AWC. See Understanding Your Water Bill | US EPA.