How do municipalities calculate reported diversion and recycling rates? From what I can tell, most are using surveys of private recycling companies without a standard system of measure or process to validate reported numbers are accurate.
There is no standard for this, but if a city offers its own recycling pickup or works with a small number of pickup companies, it would be simple to track recycling pickup quantities and consider that to be the diversion rate as a percentage of regular waste pickup.
Otherwise, the city could simply measure the reduction in waste pickup compared to projections and consider that the diversion rate. It is probably best to ask your municipality directly since there is no standard system of doing this.