21The toolbox
The short version: Two calculators for questions people ask about their own building and their own bin: how much water pressure is left by the time it reaches your floor, and how much trash a household makes in a year by the US average. They use the rules of thumb and national figures cited in this guide; your building engineer and your city have the real numbers.
Back of the envelope
Two calculators
Rules of thumb for curiosity and conversation. Building engineers, utilities and your city have the real numbers.