The phenomenon of potable water appearing milky or hazy directly from the faucet is often attributed to dissolved gases, typically air. Under pressure within the plumbing system, water can hold a greater amount of air in solution. When this pressurized water is released at the tap, the air becomes less soluble and forms microscopic bubbles, giving the water a cloudy appearance. This effect is analogous to opening a carbonated beverage; the release of pressure causes dissolved carbon dioxide to effervesce.
Understanding the underlying causes of this cloudiness is important for consumer reassurance. While unsettling in appearance, the presence of these dissolved gases is generally harmless and temporary. Historically, concerns over water quality have often been linked to visual indicators. However, in this specific case, the cloudiness is rarely indicative of contamination or a significant health risk. Municipal water treatment processes are designed to remove harmful pathogens and chemicals; the subsequent presence of dissolved gases does not undermine these processes.