That's about a drop of fluoride in a swimming pool. The average rainfall in Phoenix is about 7.5 inches per year. The department operates two wastewater treatment plants with a combined capacity of about 220 million gallons per day. The department has about 344,000 wastewater service connections. The city operates about 4,000 miles of sewer lines, the largest pipe being 90 inches in diameter.
Pipes connecting homes to the sewer system are four inches in diameter.