A flush valve utilizes a sensor to determine how close a user is to a toilet to determine whether to utilize a longer flush with more water to remove, typically, solid waste or a shorter flush with less water to remove, typically, liquid waste. If a user is in a zone that is closer to the toilet, a longer flush is deemed necessary and if a user is in a zone farther from the toilet, a shorter flush is deemed necessary. Users sometimes move between one zone or the other and the flush valve determines whether a user spends more or less time in the zones to determine whether to provide a shorter or a longer flush.