My water is normally clear but now appears milky white when I draw a glass full. What is the cause, and is it safe?
The two most typical causes for what you describe are easily distinguished from one another. The first is air, which can enter the water mains either from a main break or main isolation, or from air due to the use of certain wells in the BWL system.
The second is from deposits of calcium carbonate that have been laid down in the mains over time and then picked up due to large changes in flow.
Collect cold water from your tap in a clear glass. If the water clears from the bottom up, it’s air. If the cloudiness is caused by calcium carbonate (product of the softening process), it will clear from the top down. Neither of these is hazardous, and both should disappear within hours.
This also could be a result of aerators (screens) on your faucets needing to be removed and cleaned.