Thermos NSF/ANSI 53 Certified 22 Ounce Tritan Water Filtration Bottle, Clear Filter is NSF/ANSI 53 Certified and reduces contaminants such as: aesthetic chlorine, chloramine, atrazine and particulate class V contaminants Innovative gravity-fed filtration method in a portable filtration bottle ensures contaminants will not bypass the filter by force Open spout allows for great flow rate with no forceful sucking or squeezing required Hygienic, locking, push button lid with one-handed operation and integrated carrying loop; 22-ounce capacity Replace filter every 20 gallons (or 128 full bottles); both bottle and lid are dishwasher safe