A clogged aerator on the end of the faucet would cause the water flow to decrease in that faucet.
Aerator
A leak in the supply pipe.
With no air in the system anywhere, there would be nothing to hold pressure, so the slightest leak would cause the system to go to zero.
Dehydration can cause a drop in blood pressure. Be sure you drink enough water to stay hydrated. Pneumonia can also cause a drop in blood pressure, most likely due to dehydration.
Some causes for a sudden water pressure drop: 1) A big leak on the main supply line. 2) one or more faucets or shower heads opened on the same water line. 3) A utility water pump failure.
Generally, a drop in air pressure causes precipitation - rain, snow, sleet, hail, and so forth.
A leak probably wouldn't cause a "sudden" drop in pressure. It sounds more like the system has more users than it can supply and pressure drops when someone else turns on their shower or flushes their toilet.
A leak probably wouldn't cause a "sudden" drop in pressure. It sounds more like the system has more users than it can supply and pressure drops when someone else turns on their shower or flushes their toilet.
Yes, low oil level can cause low pressure.
Since you have a meter, it is safe to assume you are connected to a public water supply. I would think your pressure fluctuation is caused by a pump cycling and/or variation in "draw" on the system, possibly magnified by insufficient pipe size in the local main or branch.
The water pressure drop could be due to a clogged aerator at faucet out, a kinked supply line or partially closed shut of that services that fixture.
A restriction will increase pressure and decrease volume
It has to think about it, some pot is malicious and will drop your pressure but there are also angelic buds who would never do such a thing.