Why Does Kirkland Brand Water Taste Like That?

Water is supposed to taste like water. Flavored water is so popular because many people prefer their water to have a taste, so companies add ingredients to create one, or offer enhancers you can add to your own water. But if you have sampled different kinds of bottled water, and especially if you've tried the tap water from various cities, you know the taste of water is a little more complex than all that. Water can have different flavors based on the minerals that are present in it. Costco's Kirkland Signature water has a unique taste compared to many other brands, and that is intentional. The label states that minerals have been added for taste. Whether you like it or not is another matter.

Costco says it uses a "proprietary mineral blend" to achieve the water's distinct taste. The label for each bottle lists sodium bicarbonate, potassium bicarbonate, calcium citrate, sodium chloride, and magnesium oxide. Many other popular bottled water brands add minerals to improve the taste, with mixed results. Dasani water, for instance, includes magnesium sulfate and potassium chloride, but the taste did not impress us very much when we reviewed it.

So why add minerals to water? For starters, calcium changes the mouthfeel and makes it smooth, while magnesium gives it a more refreshing taste. Bicarbonate helps balance the pH, and sodium helps maintain proper fluid balance to improve hydration. If any of these minerals are out of balance, it can really throw off the taste. Too much sodium will make it taste salty, and if there is too much magnesium, the water could become bitter. People who are more sensitive to these minerals may find the taste less enjoyable.

Some fans love the taste of the Kirkland Signature water. The mineral additives make it hard to pin down a specific flavor, but it's often described as being crisp and clean tasting. Some even think it tastes slightly sweet, probably thanks to the bicarbonate. However, others feel it tastes too chlorinated.

Costco does not source or bottle its own water. Like many companies, including Walmart and Safeway, Costco's water is bottled by Niagara Bottling. Although the water Niagara bottles is purified, much of it comes from municipal sources, which means tap water. The company also says it uses wells and springs, but it is unclear what proportion comes from each source. Regardless, after purification, the requested minerals are added according to Costco's specifications. Similarly, Dasani or Aquafina include different mineral mixes to adjust the taste of their water.

While some people really enjoy the taste of the minerals, others claim it tastes stale and salty. This concern arose a couple of years ago when several fans noticed something had changed in the formulation of the water. Costco did not comment on the matter, so it is unclear whether the minerals or any other part of the formulation changed, but enough people commented on it around the same time to suggest a change occurred. Love it or hate it, Kirkland Signature water definitely stirs up opinions among those who try it.