Water-Quality Properties

pH is a measure of how acidic/basic water is. The range goes from 0 to 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. The pH of water is a very important measurement concerning water quality.

What is in that water that you just drank? Is it just hydrogen and oxygen atoms? Is it safe for drinking? All water is of a certain "quality" (and you can't tell by just looking), but what does "water quality" really mean? It can be thought of as a measure of the suitability of water for a particular use based on selected physical, chemical, and biological characteristics. Here at the Water...

Find out more about the causes of fish kills, including dissolved oxygen and toxins.

Water Quality Q&A: Why can't I rinse the soap off my hands?

Learn about water quality using pictures

What is in that water that you just drank? Is it just hydrogen and oxygen atoms? Is it safe for drinking? All water is of a certain "quality" (and you can't tell by just looking), but what does "water quality" really mean? Water full of dirt and grime might work fine for a tomato plant but would you want to drink it? Water quality can be thought of as a measure of the suitability of water for a...

Collecting samples of water isn't the only way to test water quality. The USGS actually collects fish to see if and how they were affected by local pollution and chemicals in the water, such as pesticides. Read on to find out more.

Is pure water really clear? Not really—even pure water is not colorless, but has a slight blue tint to it. In the natural world you often see water that is definitely not clear. Sediment and organics color natural water shades of brown or green. And if too much iron in present, even your drinking water can have a brown hue. Read on to investigate water color in the environment.

Dissolved oxygen (DO) is a measure of how much oxygen is dissolved in the water - the amount of oxygen available to living aquatic organisms. The amount of dissolved oxygen in a stream or lake can tell us a lot about its water quality.

You don't often think that water bodies contain oxygen, but water does contain a small amount of dissolved oxygen. A small amount, but it is essential for life in the water. Biochemical oxygen demand (BOD) generally represents how much oxygen is needed to break down organic matter in water.

Environmental DNA (eDNA) is organismal DNA that can be found in the environment. Environmental DNA originates from cellular material shed by organisms (via skin, excrement, etc.) into aquatic or terrestrial environments that can be sampled and monitored using new molecular methods. Such methodology is important for the early detection of invasive species as well as the detection of rare and...

Nutrients, such as nitrogen and phosphorus, are essential for plant and animal growth and nourishment, but the overabundance of certain nutrients in water can cause several adverse health and ecological effects.