The ZeroWater ZP-010 10-cup Pitcher is rated on multiple criteria, such as those listed below.
Lead removal: Lead removal indicates the percentage of lead that was removed by each filter.
Flow rate: Flow rate is how fast a gallon of water filtered through the cartridge. The criteria for flow rate scores differ between different types of filters. Faucet-mount, countertop, and undersink models have the same criterion; carafes and reverse osmosis models each have their own.
Clogging: Clogging measures how well the filter retains its flow rate over time and whether it stopped flowing completely before its claimed life span.