Perhaps you always put a glass of water by your bedside to drink upon arising the following morning. Maybe you leave your water glass out for hours while you’re doing errands but continue to use it when you get home. These and similar actions all result in the same thing: stale water that doesn’t taste nearly as good.

Why Does Water Go Stale?

Carbon Dioxide

Water left out for 12 hours or more goes flat. It absorbs carbon dioxide in the air to lower the liquid’s pH level, giving it a stale flavor and a more acidic composition. Carbon dioxide turns to carbonic acid when it mixes with water, resulting in the lowered pH level. Other gases may also dissolve in water that’s been sitting out, including assorted aldehydes and acetone. Keep in mind this “chemistry project” does not make the water less safe to drink, it simply affects the taste.

Room Temperature

Awaters chilled water from the pitcher in your refrigerator warms to room temperature, its flavor changes. Most cold beverages, including water and beer, “open” as they warm up, resulting in a more aromatic drinking experience. This is because the molecules in the beverage, once somewhat-suspended by cold temperatures, start moving at a faster rate to increase its aroma release rate.


Water in plastic bottles left in overly-warm environments, such as hot cars, has an unpleasant taste if the bottles contain BPA, or bisphenol-A. This plastic manufacturing chemical leaches into the water in response to hot temperatures, and unlike water affected by carbon dioxide, it presents a variety of health risks. BPA is a hormone disruptor connected to serious health issues such as heart disease, diabetes, obesity, hyperactivity, and testicular and breast cancers.

Keep your tap water clean and safe by working with Holmes Water Treatment Co. The premier water treatment company proudly serves home and business owners in Wentzville and the greater St. Charles, MO, areas, and offers over four decades of experience. Call (636) 327-6404 today to discuss your water purification requirements or visit the company online for a complete list of products and services.