Why is My Hot Water Cloudy or Milky?


When you turn on your faucet to use hot water, you may notice that the water flowing out appears cloudy or milky. This can be a puzzling sight, but there's a straightforward explanation for it. Typically, pure water is transparent, so if your hot water looks cloudy, there's a reason behind it. The cloudiness in hot water can usually be attributed to the dissolution of gases in the water.

In a domestic environment, the most probable reason for cloudy hot water is the presence of dissolved gases, which is generally harmless. Unlike contaminants that can be harmful, dissolved gases are not a health concern. In fact, we consume water with dissolved gases regularly, such as carbonated drinks or soda.

Water bodies, including lakes and reservoirs, contain various microorganisms, chemicals, solid particles, and gases. Gases are naturally dissolved in water resources, and this is vital for aquatic life, like fish, to survive.

When water temperature changes, it affects the solubility of different substances, including gases. At higher temperatures, gas molecules have higher kinetic energy and tend to break free from the water's hold more easily.

In your home's plumbing system, cold water from the city pipeline contains trapped gases. When you heat this water in your hot water tank, the air inside becomes more erratic and tries to escape. However, because of the high pressure inside the tank, the gases remain dissolved. But, when you open the tap and release the water to atmospheric pressure, the dissolved gases rapidly come out of the solution, forming countless tiny bubbles, which creates the cloudy or milky appearance.

This phenomenon occurs because water has the ability to absorb oxygen or air from the atmosphere, and colder water can dissolve more gases than hot water. When the water temperature rises, it loses its capacity to retain the dissolved air, leading to the cloudiness when the pressure is released.

While cloudy hot water is generally not harmful to health, it can indicate the presence of unsafe pathogens or chemicals, though this is unlikely in most cases. To determine if the cloudiness is due to contamination or not, you can simply open your tap and observe if the water clears up after a few minutes. If it doesn't clear up, you should contact your water supplier, as there may be an issue with the water quality.

To address cloudy hot water, first, you need to identify the cause. If the cloudiness is only present when using hot water, then the water heater is likely the cause. However, if the cloudy water is coming from every faucet in your house and doesn't clear up after a few minutes, it's more likely related to your plumbing system or water supply, and you should contact your water supplier to investigate the potential for contamination.