Milky or cloudy water looks alarming, but it is one of the easiest symptoms to sort at the kitchen sink. Three different causes produce cloudiness, and each behaves differently in a glass. Work through the checks below in order, and write down what you see before you make any calls.
Step 1: Let a glass sit and watch it
Fill a clear glass from the cold tap and set it on the counter for a minute or two. Watch the bottom and the top.
If the water clears from the bottom up, or the cloud breaks into tiny bubbles that rise, you are looking at dissolved air. Water holds air under pressure, and when pressure drops at the tap, the air comes out of solution. This is common after a new install, after a service visit, after a power cut, or after lines have been opened and closed. It is harmless. Running the cold tap for a minute usually clears it on its own.
Check the hot tap as well. If only the hot side is cloudy, the water heater or its line is a more likely place to look than the softener.
Step 2: Look for a layer that settles
If the cloudiness stays after a few minutes and a fine layer collects on the bottom of the glass, the water is carrying solids. Rub a little of the settled material between your fingers. Gritty particles point to sediment from the supply or to fine resin particles from the softener. Resin is bead-like and can break down into fines, especially after the unit has been disturbed. Ask the installer or service company whether the lines were fully flushed after start-up or after the last visit.
If a pre-filter or sediment filter sits ahead of the softener, check its housing. A cartridge left too long, or one installed without its seal in place, can let material through. If you are unsure whether the cartridge matches the housing, treat that as a question for the service company rather than a guess.
Step 3: Compare one tap with the rest
Note whether the cloudy water shows up at every tap or only one. A problem at a single faucet usually sits at that fixture. Unscrew the aerator at that tap and look inside the screen. Grit, flakes, or debris there explains cloudiness at that tap only. Clean the screen, reinstall it, and run the tap again. If the rest of the house runs clear, you have your answer.
Step 4: Recognise rust color
Water that looks yellow, orange, or brown, or that leaves reddish staining in the sink and tub, points to iron or another metal rather than air or fines. Do not treat color as a diagnosis on its own. Hold the glass against a white background and compare it with the clear sample you took earlier. Rust color that persists after the water has run for several minutes is a reason to have the water tested before anyone changes equipment. For the wider set of checks a homeowner can run, the Missouri Water Softener Buyer's Guide walks through them in order.
What to write down before you call
Keep a short note covering which taps are affected, whether the problem is hot, cold, or both, whether the glass clears from the bottom or stays cloudy, whether anything settled and what color it was, when you first noticed it, and any event just before it started, such as a service visit, a salt refill, a power cut, or a plumbing job. A clear note lets the service company check the likely cause first instead of starting from zero.
What to ask the service company
Ask whether the unit was flushed and rinsed after its last service or install. Ask whether a pre-filter was fitted or changed, and whether the cartridge matches the housing. Ask what they would check first if the glass still stays cloudy after the air test. A useful answer names the next step and says what would rule a cause in or out. If the answer is vague reassurance, ask again until you get a specific check.