Costco’s Kirkland water bottles are inexpensive and feature a clean, quality taste that has garnered a devoted fan base. However, who produces these bottles is a mystery for many.

The brand behind the bottles is Niagara Bottling. Founded in 1963, the brand sold water under its name until the 1990s, when it began bottling water for Costco’s Kirkland label.

That said, other companies, like Walmart, also source their bottled water from Niagara Bottling, making the brand the largest supplier of private-label water in the United States.

The details of Niagara’s water sourcing and processing methods remain inexact, but the brand prides itself on its purification methods, like microfiltration and reverse osmosis.

Niagara's water is sourced from wells, springs, and municipal water sources before it’s purified. Niagara also adds minerals to the water before bottling to boost its taste.