Comparing Water Filtration Systems
Glossary

% Reduction of All Contaminants. Based on known contaminants in Seattle water supplies from the Tolt and Cedar watersheds.

Contaminant Reduction. 100% removal is only a theoretical possibility. Therefore, reduction is used to describe contaminants that are significantly reduced, estimated at greater than 95% removal.

Time to Produce One Gallon. Unlike other equipment, distillers, reverse osmosis and pitcher filters produce water very slowly. These methods of water treatment require a storage reservoir to collect the water.

Maximum Capacity. For filtration equipment, this refers to the number of gallons that can pass through the filter before it needs to be changed. In the water treatment industry it is considered a good practice to change filtration material at least once per year. So, if the capacity claims exceed what your needs will be, you should still plan on changing filters at least once per year. The capacities listed for distillers and reverse osmosis systems refers to the total number of gallons that can be retrieved from the reservoir in a single day.

Filter Service Frequency. The low range is based upon manufacturer's stated capacity and a base usage rate of 500 gallons in a year. This reflects the typical drinking/cooking water demand for a 2 to 3 person household. The high range is calculated by adjusting the low range number for the higher sediment loading commonly found in Seattle water supply. The low end of the range therefore represents a best case scenario and the high end of the range a worst case scenario..

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