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Milky Tap Water: What Are the Causes and Solutions?

So you turn the tap for a glass of water, and you notice that the liquid coming out of it isn’t clear but milky. But then, after a few minutes, the milky water starts to clear up until the cloudiness is all gone.


What could have caused the milky appearance, you might ask? Well, there are a number of possible reasons for this:

  1. Air bubbles

Milky water, also known as white water or cloudy water can be caused by air bubbles that get trapped in the pipes. When water-soluble gases such as oxygen, chlorine, hydrogen sulphide, carbon dioxide and others enter the mains supply, they create air locks or air pockets in the plumbing system. As these gases are carried along the pipes, they get dissolved in the water. When you open the hot water tap, the pressure is released and the dissolved gases spurt out into millions of tiny air bubbles. This is what gives your hot water the white, milky appearance.

All main supplies contain a small amount of air, but a tear or damage in the pipe may pull in additional air. A change in the water pressure may also be to blame. An increase in pressure causes excessive air to get trapped in the pipeline. This can happen if:

  • Your home’s plumbing system and heater use the well system.
  • There is disturbance in the water distribution pipes, such as when utility companies switch from one well source to another.


Milky water is also common when the weather is cold. As water passes through the pipes in your home, it is mixed with oxygen. When it’s cold outside, more oxygen bubbles get into the water, hence the cloudy water effect.

If the water is left to stand for several minutes, the dissolved gases will start to separate and the cloudy effect will go away. This reaction is very much similar when you pour carbonated drinks into a glass.

  1. Your water heater’s anode

If water from your hot tap is excessively cloudy and generally stays that way, the issue may be with your water heater itself.

The anode rod (factory installed) in your hot water cylinder is there to inhibit rust by maintaining an invisible film of free hydrogen on the entire surface of the heater. The anode is placed where rust initially forms – in the water tank. It acts as “sacrificial metals” which draw the metallic ions in the cathodic area and keep them from going into the solution, protecting the tank against corrosion. This is most common in water heaters that are less than one year old. It disappears over time.

When water from ALL of your hot water taps turns milky, it could be a sign that your anode needs replacement. The good news is replacing an old anode rod is relatively easy and inexpensive.

  1. Sediments

Sediments such as sand, dirt and tiny particles from rocks in the ground can get into your water supply. This can happen when there are drilling activities nearby.

It’s easy to tell whether the milky appearance of your hot water is caused by air bubbles or by tiny particles. Wait for the water to clear up and watch. Air bubbles tend to rise to the water’s surface, while sediments tend to sink into the bottom or do not clear at all.

Like air bubbles, the presence of particles in the water does not make it harmful but aesthetically unpleasant.

  1. Methane Gas

It’s highly uncommon but not impossible. This problem can occur in areas where gas and oil wells are nearby. Methane is a flammable gas, so having it in your water source can pose problems. It is hard to detect since it is odourless unless the water also contains hydrogen sulphide. In addition, methane acts the same way as air bubbles –they also rise to the water surface and escape into the open air.

The usual fix for water containing methane gas is installing an aerated tap, which permits the gas to dissipate faster. The aerator must be vented to the open air to prevent the risk of fire or explosion.

Is the water safe to consume?

You may notice a difference in the smell, taste and overall aesthetic of your water. But as off-putting as milky water may look, it is completely harmless and safe to drink or use.

However, please note that cloudy appearance that is another colour other than white (i.e. brown, yellow or green) can indicate presence of bacteria, metals, minerals or other contaminants. This is often the case when the cloudy water effect does not clear up after some time. Cloudy water of this kind may have adverse health effects when consumed.

What can you do?

If water from all of your home’s taps appears cloudy, the problem could be from a pressurised water system. If only a single tap produces cloudy water, then the issue is with that fixture alone. Cloudy water from a hot tap can be an indication of a problem with your water heater.

Milky water caused by air bubbles or dissolved gasses can be resolved with aerated taps. Sometimes it cannot be fixed entirely, but aerating the water significantly reduces bubbles.

The cloudy water effect should not last longer than 24 hours. If the milky appearance of your hot water bothers you, you can:

  • Keep the taps running until your water runs clear.
  • Check with your neighbours to find out whether they are having the same issue. If such is the case, it is advisable to notify your water supplier of the problem.

If the situation doesn’t clear up itself, it is advisable to call in Hot Water Cylinders NZ to check whether things look normal or you need to take further steps.

We will come and take a look, so we can determine the right reasons and provide appropriate solutions. Contact us on 0800 832 638!