Under the new model — a tiered-assistance program, thus the name TAP — payments will be tied to a household's income, not water usage. (Customers with unusually high usage, potentially a sign of a leaky pipe or running toilet, will be required to meet with a conservation specialist.) The program will be open to anyone with an income under 150 percent of the federal poverty level, or $36,900 for a family of four. The payments will range from 2 percent to 4 percent of household income.