Have you sometimes noticed your potable drinking water out of the tap is cloudy or milky (also known as white water)? Especially the water coming out of the hot water tap? This is caused by tiny air bubbles in the water. It is completely harmless.
Think of it like a soft drink can. The gasses are trapped within the water. (In the case of the soft drink - it is carbon dioxide.) When the can is opened and the pressure is released, the gasses come out as tiny air bubbles. The same thing is happening in your water pipes and drainage.
Hot water is better at trapping the air than cold water so you normally only see it in hot water. [As a side note - this is not the same as "having air in your hot water pipes".]
You can test it - if you fill a glass with the water and let it stand - it should clear itself quite quickly.
If you have trapped gasses in your hot water as above - then this is normal and harmless.
You can perform some simple tips to reduce the occurrence of cloudy hot water.
As a good start - begin by checking the pressure of your hot water system tank. You can also flush your hot water system - by opening the Pressure Relief Valve - or check the anode. These simple tasks can not only help minimise cloudy hot water, but they will also extend the life of your hot water system.
Also check the aerator in your tap. The aerator is a small internal screened cap that fits on the end of the tap. It is designed to reduce the amount of splash and soften the stream. Sometimes this aerator can become clogged with minute particles and increase the tap pressure - this in turn can lead to more cloudiness in your water.
There are a few cases where cases of cloudy water may need to be checked.
If your water has a tinge of colour, is milky white, or looks slightly muddy - then this could be an indication of council works being carried out in your area on the water lines. This may take up to a few hours to clear out.
If your water is still muddy after a few hours or it regularly occurs after heavy rain - this can be a sign of damage to your water pipes. It can also be an indication that your hot water system may need repair or maintenance.
Instances where water in some parts of the house are cloudier than others can be another sign of pipe issues causing increased water pressure or being damaged.
In these cases you should consult a local plumber.