Published: May 29, 2025
By Lisa Martinez, Water Quality Specialist
Lisa holds a degree in Environmental Science and specializes in private well water safety and treatment.
From inspecting residential wells over the past two decades, I can tell you this: most well problems start small and get expensive the longer they are ignored. The guidance below reflects what I have actually seen in real well systems, not just what the manuals say.
Have you ever taken a moment to wonder about the clarity of the water flowing from your taps or the sparkling streams that you come across during walks in nature? What exactly might be clouding these waters, and how crucial is it for them to be clear? That’s where the concept of turbidity steps in. This article will guide you on a journey to understand turbidity and just how dangerous it might—or might not—be in your daily life and the environment.
What is Turbidity?
Turbidity is a term that describes how clear or cloudy a liquid appears. It’s not the color of the liquid but rather the cloudiness or haziness that you’re observing. When you see a body of water that isn’t clear enough to see through, what’s coloring your view is turbidity. Essentially, it’s a measure of the concentration of suspended particles within water.
Understanding Suspended Particles
Suspended particles in water come from a variety of sources, both natural and man-made. These particles can include soil, sediment, algae, plankton, and other microscopic organisms. Suspended solids and particles in the water scatter light, causing the water to appear cloudy. The more particles in the water, the higher the turbidity level, and the murkier the water.
Measuring Turbidity
Turbidity is typically measured using a device called a nephelometer, which assesses the intensity of light scattered at a 90-degree angle as it passes through a water sample. There are also older methods like the Secchi disk, which involves lowering a black and white disk into the water until it disappears from view—a simpler though less precise measure.
Here’s a quick look at typical turbidity measurements:
| Turbidity Level (Nephelometric Turbidity Units – NTU) | Water Description |
|---|---|
Sources
The guidance in this article is informed by the following authoritative sources:
- USGS — Ground Water — U.S. Geological Service data on groundwater levels, well construction, and water quality.
- EPA — WaterSense — EPA guidance on water conservation and water quality standards.
- CDC — Water and Wellness — Centers for Disease Control and Prevention guidance on safe drinking water.
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