Many of us have heard the phrase “the solution to pollution is dilution.” But what does this really mean? Can it be applied to solving the large pollution issues we face globally today?

This article will walk you through what the phrase means, where it comes from, and most importantly, whether dilution is really the solution to pollution in the modern day.

Background Info: What Factors Are Responsible for Environmental Pollution?

Table of Contents

What does “the solution to pollution is dilution” mean?

Why is dilution no longer a solution to pollution?

Are there situations when the solution to pollution is still dilution?

What is a solution for pollution?

What does “the solution to pollution is dilution” mean?

To best understand this phrase, we have to define a few terms. First, pollution occurs when harmful materials enter into the environment. Pollution can take the form of:

• Gasses or smog (air pollutants)
• Toxic chemicals
• Heavy metals
• Material waste

Dilution is the process of making something thinner or weaker by adding another substance. For example, very salty water can be diluted by adding more fresh water. 

The idea of “the solution to pollution is dilution” is that by adding another substance (water) to pollutants, the pollution’s concentration is lowered and made weaker. The concept of pollution management through dilution is that dilution essentially works to decrease the concentration of pollutants compared to the natural or clean environment. 

It’s important to note that this concept historically applies primarily to water pollution, with the idea that putting pollutants in bodies of water (thereby “diluting” the contaminants) was an acceptable method of pollution control. It is no longer an accepted form of pollution management.

History of pollution-management through dilution

For many years, the primary strategy to reduce environmental pollution in bodies of water was dilution, or adding water. Because a body of water can only absorb a certain amount of pollutants (known as its assimilative capacity), people believed that by adding fresh water, it would reduce the amount of pollution in the water. While this may be true in smaller-scale examples, such as a chemistry lab, dilution is no longer the solution to pollution in the case of environmental pollution.

The “solution to pollution is dilution” was the accepted standard for pollution for many years in the 18th, 19th and into the 20th century. This led to many industries simply dumping their waste, including trash, chemicals, and even sewage into waterways. It was believed that simply “diluting” pollution was enough to stop its harmful impacts on the environment and human health.

However, as populations grew and as increasingly toxic chemicals began being used industrially, the U.S. government eventually realized that water pollution was becoming a significant problem that dilution could not address. In 1948, the U.S. government passed the Federal Water Pollution Control Act of 1948, which was the first law in the U.S. that attempted to control water pollution. It was amended in 1972, which created further regulation around discharging pollutants into water and created requirements for industry wastewater standards.

In 1988, the U.S. government passed the “Ocean Dumping Ban Act,” which made it illegal to dump industrial waste into the ocean. In some ways, this signified a true end to the concept of dilution to stop pollution, as regulators realized that simply dumping waste and creating pollution, even in as large a water body as the ocean, could not be remedied by dilution.

Why is dilution no longer a solution to pollution?

There are many reasons why the phrase “the solution to pollution is dilution” is not true for environmental pollution. When it comes down to it, the main issue is that it’s just not that simple; dilution alone is not enough to decrease the pollution concentrations, and there are too many factors at play.

1. Our population is too large and there is too much waste

The biggest issue with the idea that dilution is the solution to pollution is the size of our modern population. While dilution may work to prevent pollution on a small-scale, it does not work to address large amounts of contaminants. Dilution may have been a more effective solution to pollution when populations were small, but it no longer holds today.

The human population has grown significantly, so we create much more waste. For example, while the actual amount of industrial waste created in the U.S. today is unclear, some estimates believe that as much as 7.6 billion tons of industrial waste is created each year.

The environment cannot handle the huge amounts of waste we as a society are creating in the modern day.

2. Not all pollutants can be degraded

Many chemicals used in industrial processes today cannot be degraded by natural processes. When these chemicals are dumped into waterways, while they may be diluted, they do not disappear and can linger for years. If untreated industrial wastewater is dumped into freshwater, the chemicals may be ingested by aquatic wildlife or humans.

3. Some chemicals bioaccumulate or create toxic byproducts

When some chemicals do degrade in water, they can actually create byproducts that are even more toxic than the original chemical itself. For example, when pharmaceutical waste ends up in water, it is exposed to other materials (like sediments) and conditions (like sunlight) that do cause it to degrade or transform into a byproduct known as “degradation products.” These byproducts have been shown to be toxic to humans.

When a pollutant does not degrade, it can also bioaccumulate, meaning that it gradually accumulates in marine life. Bioaccumulation is typically defined as when organisms absorb substances faster than it degrades or is eliminated in the environment. Bioaccumulation can spread the chemical throughout the food chain, as when one animal eats another one that contains the chemical, it absorbs the chemical as well. This process is known as biomagnification.

4. Some contaminants are harmful even in tiny amounts at low concentrations

Even very small concentrations of some chemicals can be extremely harmful to human health. Even if dilution does work to lower the concentration of pollution, it does not mean that the remaining concentration is not harmful. For example, some chemicals can hurt wildlife even at a concentration as small as parts-per-billion.

Are there situations when the solution to pollution is actually dilution?

Much of wastewater treatment is essentially treated with cleaning and then dilution. First, the wastewater must be cleaned in a wastewater treatment plant. It is then dumped into waterways, which often ends up still contributing small amounts of contamination to the water. Dilution, or the mixing of wastewater with a river or lake, can help reduce the impact of any contaminants left in wastewater after cleaning.

Additionally, dilution of contaminants is still important, even if it’s not an actual solution to pollution. If there are too many contaminants and not enough water, this can harm animals and other life in the body of water. Diluting contaminants is still helpful, although it does not actually reduce or solve pollution.

What is a solution for pollution?

The best solution for industrial water pollution is to keep contaminants out of the water in the first place. As mentioned above, the U.S.’ Clean Water Act aims to restrict dumping of waste in waterways, and enforces requirements for wastewater treatment.

Today, industries that wish to dump wastewater must obtain a permit from the EPA. Additionally, any effluent that is released into water must be tested for toxicity to aquatic organisms using the Whole Effluent Toxicity (WET) test.

Relying on industrial and agricultural processes that use fewer harmful chemicals is another positive step towards avoiding the creation of pollution in the first place.

Ways that individuals can help prevent water pollution include:

• Using natural fertilizers and avoiding using chemical pesticides or herbicides in your garden
• Washing your car or other mechanical equipment where the water will flow through gravel or grass, rather than pavement. Gravel and grass can help act as a natural filter.
• Recycling or disposing of waste properly to avoid physical waste in lakes, rivers and the ocean