Clean water is important to ensure healthy drinking water, healthy crops, and healthy ecosystems. However, runoff from industry and agriculture can pollute waterways and make for unsafe drinking water containing harmful chemicals and pathogens. Water quality standards are an important tool to assess and compare water to control pollutants.
In this article, we’ll explain the following questions about water quality standards:
- What are water quality standards?
- How is water evaluated?
- How are water quality standards set?
- How are water quality standards measured?
Yale’s Environmental Performance Index Survey (EPI) looks at a couple of different parameters relating to water quality and gives each country a score based on their performance in the category:
- Drinking water: Measured in life years lost per 100,000 people per day due to exposure to unsafe drinking water
- Wastewater treatment: The proportion of wastewater that is treated multiplied by the proportion of people connected to a sewer system
Looking at these two parameters allows us to view overall water pollution in a country as it compares to other countries.
In the United States, we look at similar parameters to determine water quality in an area. The Environmental Protection Agency (EPA), like the EPI, looks at both drinking water and wastewater treatment. Although the EPA standards only apply by law only in the United States, they are a good indicator of water health globally and will give us a specific look at how water quality is evaluated.
What are Water Quality Standards?
Water quality standards are benchmarks set by governments to determine if water is safe and healthy.
How is Water Evaluated?
Water can be evaluated in a few different ways based on whether the water is for human and animal use, or if it is wastewater that needs to be treated so that it does not pollute bodies of water.
Evaluating Water for Health of Humans and Aquatic Life
Water quality standards in the United States are set on a state-by-state basis, so there is no one set of standards that applies nationally. Here are some parameters that researchers commonly evaluate:
- pH
- Known carcinogenic chemicals
- Toxic heavy metals like lead
See the full table of recommended human health water criteria.
See the full table of recommended aquatic life criteria.
Evaluating Wastewater Treatment
Areas are also evaluated based on their wastewater treatment according to the Clean Water Act of 1972 which sets standards for and evaluates:
- Stormwater treatment
- Agricultural runoff treatment
- Treatment of municipal biosolids
Standards for wastewater treatment prevent toxic runoff into bodies of water that could harm aquatic life and human health.
How are Water Quality Standards Set?
The EPA sets recommendations discussed above by reviewing scientific literature on the effects of pollutants on human health and aquatic life. Scientific research on the effects of many substances that occur in drinking water is discussed to make decisions about what should be tested, and what the standards are. The recommendations are periodically updated in accordance with new scientific findings.
In the United States, states can choose one of two options to set their water quality standards:
- Follow the EPA recommendations
- Develop their own standards based on scientific research
If states or territories decide to set their own standards, the EPA must evaluate and approve of the standards. Once standards are set, states are regularly evaluated to ensure the water quality and wastewater treatment meets or exceeds the agreed-upon standards.
How are Water Quality Standards Measured?
Scientists use various devices to regularly test bodies of water for things like pH, water hardness, and lead content if the water is for drinking. Wastewater is measured to test that it is being treated properly and not able to harm ecosystems.
If water standards are below those agreed upon by the state, tribe, or territory, the EPA takes action to identify the source of the pollutant, and correct the pollution levels in the water to ensure it is safe for aquatic life or drinking water.
Key Takeaways
- Water quality standards are benchmarks set by the government to be used as a guidance that determines healthy or unhealthy water
- The Environmental Performance Index Survey, as well as the Environmental Protection Agency both, look at drinking water health and wastewater treatment to determine water quality in an area
- Water used by humans and water that hosts aquatic life is measured for pollutants like pH and lead
- Wastewater is tested to ensure that runoff from industrial and residential waste is not harming ecosystems or impacting drinking water
- The standards are recommended by the EPA, and states can choose to follow the EPA standards, or create their own based on scientific research
- If water quality does not meet the set standards, the EPA takes action to identify and manage the source of pollution