Low Water Pressure in the House: Finding the Actual Cause
Start with one question: one fixture, or all of them?
Everything about diagnosing pressure comes down to this. If a single faucet or shower is weak and the rest of the house is fine, the problem is at that fixture and it is almost always cheap. If the whole house has gone soft, the problem is upstream and it is a bigger conversation.
Walk the house and check hot and cold separately at each fixture. That five-minute walk narrows the possibilities more than anything else you can do.
If it is one fixture
Unscrew the aerator from the end of the tap. On kitchen and bathroom faucets this is the small screen that unthreads by hand or with a cloth for grip. If it is packed with white or brown grit, that is your answer — mineral scale, which is common across a lot of Arkansas. Rinse it, clear the screen and refit.
If the aerator is clean, the next suspect is the cartridge inside the faucet, particularly on single-handle mixers. If the fixture is a shower, the same applies to the shower head and the mixing valve.
One more possibility worth checking: the angle stop under the sink may have been knocked or only partially opened after previous work.
If it is the whole house, hot side only
That points at the water heater. Sediment in the tank, a failing dip tube or a partially closed valve on the heater outlet will drop hot pressure while cold stays normal. A heater that also rumbles is almost certainly full of scale.
If it is the whole house, hot and cold
Now we are looking at supply. The usual suspects are the pressure regulator, a partially closed main valve, a leak in the service line, or corroded pipe.
A pressure regulator that has failed is a common and reasonably inexpensive fix. A main valve that got partially closed during previous work is free to fix. A service line leak shows up as a meter that turns with everything off, and wet ground somewhere between the meter and the house.
The one nobody wants to hear is galvanized pipe. Steel pipe rusts inward over decades until the working diameter is a fraction of what it was. Pressure falls off so gradually that most owners adapt to it without realizing. If the house is old enough to have galvanized supply lines and the water sometimes comes out tinted, that is what you are dealing with, and the answer is repiping rather than repair.
What to check before calling
Note whether it is one fixture or all, hot or cold or both, whether it happened suddenly or gradually, and whether the water is ever discolored at first draw. Those four answers let us tell you on the phone which of the above it probably is, and roughly what the fix involves.