Family-owned by the Peykoffs since 1963, the company sells products under many names, including Niagara, now the leading private-label bottled water brand in America.
The brand offers much more than just purified water, including distilled and alkaline options as well as colorful vitamin waters, protein shakes, and even iced tea.
Niagara brand also provides for other big grocery chains, but Costco's 16.9-ounce bottles are infused with a special mineral blend that makes the taste unique to the store.
Kirkland's water uses "state-of-the-art purification, filtration, and reverse osmosis technologies." On Amazon, comments boast about the water's smooth flavor and cheap pricing.