Water that looks wrong does not always mean the water is wrong. Cloudiness, a milky tint, and specks that show up in a glass can come from dissolved air, from fine sediment, or from a particle problem upstream. Each one points to a different next step, so the first job is to tell them apart.
Run a glass and watch it for a minute
Fill a clear glass from the cold tap and set it on the counter. Watch it for a minute or two. If the cloudiness rises and clears from the bottom up, that is dissolved air coming out of solution, and it is usually harmless. Run the tap again and you should see the same pattern repeat.
Look for particles that settle
If the glass stays cloudy throughout, or if fine grains collect at the bottom, you likely have sediment. Settled sediment often looks gritty, sandy, or rust-colored. Pour a little into a white dish and look at it in daylight. Rust-colored or dark specks that stay put point toward sediment or iron, not air.
Compare the hot and cold taps
Check the cold tap and the hot tap separately. If grit appears only on the hot side, look at the water heater, since sediment collects there. If it appears on both sides, look upstream of the split, at the main line or at any filter already in the house.
Clean the aerators before you decide
Faucet aerators catch small debris. Unscrew each one, rinse it under clean water, and run the tap again. If the cloudiness or grit goes away, the cause was the aerator and not the supply. This takes a few minutes and rules out a common false alarm before you call anyone.
When to bring in a provider
If the test points to sediment that persists after you clear the aerators, write down what you saw, when you saw it, and which taps show it. Ask a provider to test the supply and recommend a filter type, size, and location. Those notes will make the first visit faster. For a list of providers to start from, see the provider directory.