Water Science School
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? 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 particular use based on selected physical, chemical, and biological characteristics
All Water Quality Science Topics
View a list of all of our science topics about water quality.
Learn moreWater Quality Data for the Nation
The USGS National Water Information System (NWIS) contains extensive water-quality data, both real-time and historical, for the nation.
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Water Quality Information by Topic
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...
pH and Water
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.
Water Quality Questions & Answers
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...
Desalination
Humans cannot drink saline water, but, saline water can be made into freshwater, for which there are many uses. The process is called "desalination", and it is being used more and more around the world to provide people with needed freshwater.
Acid Rain and Water
Depending on where you live, maybe you've heard of acid rain. Now, acid rain is not pure acid falling from the sky, but rather it is rainfall or atmospheric moisture that has been mixed with elements and gases that have caused the moisture to become more acidic than normal. Pure water has a pH of 7, and, generally, rainfall is somewhat on the acidic side (a bit less than 6). But, acid rain can...
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The U.S. Geological Survey's Water Science School
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Water Science Photo Galleries
Learn about water using pictures
Water Q&As: Why does my water smell like rotten eggs?
Learn about the causes of bad-smelling water and what you can do about it.
Water Q&As: How does our swimming pool stay so clean?
Learn about different methods to keep swimming pool water clean and safe.
Water Q&A: How is sewage and wastewater treated?
Learn about different sewage and wastewater treatment methods.
Water Q&A: What causes fish kills?
Find out more about the causes of fish kills, including dissolved oxygen and toxins.
Water Q&A: Is groundwater always clean?
Learn about groundwater quality and potential contaminants.
Water Q&A: Where does our home wastewater go?
Learn what happens at a wastewater treatment plant.