The ban only applies to irrigation of non-functional turf in the commercial, industrial, and institutional sectors and only applies to irrigation with potable water. It does not apply to residential lawns or any turf that is regularly used for human recreational purposes, such as community spaces, or sports fields and other turf spaces used for recreation or events. The regulation does not ban the irrigation of trees or other non-turf plantings. There is an exemption process available for certain low water using turf species and irrigation approaches. To be exempt from the ban, an owner or manager must provide to their water supplier evidence that they have met two requirements: (1) the user must certify that the turf species needs low levels of water (a plant factor of 0.3 or less; “plant factor” is a factor used to estimate the amount of water needed by plants – see section 491 of title 23 of the California Code of Regulations) and (2) the user must demonstrate that the turf is irrigated in a way that uses low levels of water (less than 40 percent of reference evapotranspiration). For more information on plant factors and reference evapotranspiration, see the state's Model Water Efficient Landscape Ordinance.