The appearance of cloudy, hazy, or opaque water, often described as “murky,” raises concerns about safety and quality. This visual change means that something is physically suspended in the water supply, distinct from discoloration like yellow or brown tinting. Understanding the origin of this cloudiness is the first step in addressing water quality and ensuring the supply is safe for household use.
Air Bubbles: The Most Common Cause
The most frequent explanation for milky or cloudy tap water involves microscopic air bubbles trapped within the liquid. This occurs when water is subjected to increased pressure, allowing a greater volume of dissolved air to be absorbed into the supply line. When the water exits the faucet and pressure returns to normal, the trapped air is released as tiny bubbles.
A common example occurs when cold water from a deep source is significantly colder than the ambient temperature, causing dissolved gasses to rapidly precipitate out. This cause is entirely harmless and poses no risk to health or plumbing. A simple diagnostic test can confirm if air is the source of the cloudiness.
To perform the test, fill a clear glass with the murky water and observe it closely for 60 seconds. If the cloudiness begins to clear, starting from the bottom and moving upward, the culprit is confirmed to be harmless trapped air. The bubbles rise and dissipate, leaving behind clear water that is safe to drink and use.
Suspended Solids (Sediment, Rust, and Scale)
If the cloudiness does not dissipate after a minute, the murkiness is likely caused by various physical particles known as suspended solids. These contaminants are introduced into the water from external ground disturbance or internal pipe corrosion. Sediment, such as silt or fine clay particles, can enter the water system following heavy rainfall or when nearby construction disturbs the ground.
Another common source of suspended solids is the internal corrosion of older plumbing materials, particularly galvanized steel or cast-iron pipes. As these pipes age, iron oxide particles (rust) flake off the interior walls and become entrained in the flowing water. This typically results in a grayish or brownish tinge to the cloudiness, often noticeable after high-volume water use.
Homes in areas with hard water often accumulate mineral deposits, or scale, primarily composed of calcium and magnesium carbonate. These deposits adhere to the inside of pipes and hot water heaters. If the flow is suddenly reversed or significantly increased, these deposits can be dislodged, causing a temporary, milky appearance. This particulate matter indicates a disruption in the water system that warrants further investigation.
Determining the Source and Next Steps
Once air bubbles have been ruled out, determining the precise origin of the suspended solids is the next practical step. The first diagnostic question involves identifying which taps are affected: Is the murky water coming from the cold tap, the hot tap, or both? If the cloudiness is present only when running hot water, the issue is likely isolated to the hot water heater or its immediate lines, suggesting a buildup of mineral scale.
If the problem occurs only when cold water is run, or if it affects both hot and cold supplies, the issue is situated earlier in the supply line, either in the main plumbing or the municipal system. Another observation is whether the murkiness clears after allowing the tap to run for a few minutes. Water that quickly clears suggests the particles are localized within the home’s plumbing, perhaps breaking loose after long periods of stagnation.
If the problem is widespread throughout the home and does not clear after several minutes of flushing, or if it appears consistently, the cause is likely external to the house. Contacting the municipal water utility is the appropriate action, as they can investigate potential issues in the main supply lines. If the issue is isolated to a single faucet or persists only within the home’s perimeter, consulting a licensed plumber is advisable to inspect and potentially flush the internal lines.