Effects of Fertilizer Runoff on Drinking Water Quality

Since ancient times, many farmers have relied on organic fertilizers to keep soil healthy and productive. But with the development of petroleum-based synthetic fertilizers, used to give plants a quick fix of nutrients, farmers and homeowners began relying more heavily on chemical/inorganic fertilizers than the natural, healthier alternatives, like manure, compost, and ground bones.

With this shift towards synthetic fertilizers, coupled with their overuse and misuse, toxic fertilizer runoff became a significant cause of pollution, degrading the natural environment and leaching loads of potentially dangerous chemicals into aquatic ecosystems and waterways many depend on for drinking water.

If you want to learn more about fertilizer runoff and its effects on drinking water quality, continue reading to understand what it is, what happens when you drink water containing fertilizer, and how to remove fertilizer chemicals and compounds from your drinking water supply.

What is Fertilizer?

Fertilizer is a chemical or natural substance added to soil or land to enhance its fertility. Like humans, plants need various nutrients to grow and thrive. While our nutrients come from different foods we eat (vegetables, fruits, dairy, meat, grains, and so on), plants obtain most of the nutrients they need from the soil. However, some soil types lack the necessary nutrients for the plant to flourish, or the nutrients are bound to the soil in a form that makes it difficult for the plant to use. This is where fertilizer comes in.

Fertilizer is applied to the soil to supply the plants with the nutrients they need (primarily nitrogen, phosphorus, and potassium) in a form that the plant’s root can easily use. It is typically added to the soil when planting seeds or young plants to help them get established.

Fertilizer Runoff: A Growing Threat to Water Quality and Human Health

Fertilizer can or may be added to the soil throughout the plant’s life to help keep it healthy and growing strongly. However, too much fertilizer can kill the plant, and excess fertilizer can run off into streams and lakes, causing toxic algal blooms that can harm aquatic life and even people and their pets. Excess fertilizer runoff from lawns and agricultural applications also contributes to marine “dead zones” in coastal areas.

Fertilizer runoff typically contains a variety of nutrients from fertilizer. But since runoff is usually a nonpoint pollution source, it can pick up other unwanted elements as it journeys to its final location, including sediment, microbes, pesticides, and heavy metals, to name a few. Unfortunately, the runoff typically ends up in groundwater and local waterways, contaminating them and possibly reaching our drinking glass. Once ingested, it can cause severe illness and even death if not filtered out.

What Causes Fertilizer Runoff?

While plants get what they need from fertilizer, it doesn’t always stay where it is applied. Instead of remaining in the field, lawn, or garden, they can run off into other areas, possibly contaminating groundwater and surrounding land.

Fertilizer runoff can occur because of the following:

Heavy rainfall. Heavy rains can sweep fertilizer away from the soil around plant roots, wash them into groundwater, or contaminate soil in other areas with chemicals.
Excessive irrigation. If agricultural fields or garden soil becomes saturated with water, the excess water will run off to drier land that can absorb more water, bringing the fertilizer with it.
Using too much fertilizer or applying it to soil with sufficient nutrients to be strong and healthy is almost guaranteed to cause runoff. When healthy, well-established lawns or crops are fertilized anyway, the nutrients that the grass or crops don’t use will run off with the next shower or watering, possibly ending up in our streams and reservoirs. The same happens when too much fertilizer is applied to crops. Once the plants’ roots become saturated, the remaining fertilizer will leach into less saturated areas.
Bad timing. Fertilizer applied to frozen or partially thawed ground cannot penetrate the soil as quickly as it would otherwise. As a result, it is likely to run over the hard ground until it reaches a more hospitable environment, like a lake, stream, river, or warmer soil. Furthermore, if you fertilize where grass and other plants are dormant, their roots won’t be able to absorb the fertilizer, causing the rain to wash it away more quickly.
Improper yard waste disposal. If you fertilized and cut your lawn recently, the grass clippings may contain fertilizer residue. If you dispose of them inappropriately, say in a nearby open lot, the next heavy shower could carry away those residues and contaminate soil and water elsewhere. If they end up in drains, they could leach fertilizer chemicals into the water supply.

How Fertilizer Runoff Pollutes Our Waterways

During heavy rains or flooding, water running off lawns, gardens, or agricultural fields can pick up excess fertilizer from the soil and wash it down storm drains, often leading to rivers, lakes, bays, and other waterways.

Fertilizers that find their way into local water bodies help fuel the rapid and harmful growth of algae and other aquatic plant life. Often, the growth is so explosive it creates monstrous “algal blooms,” causing thick green or greenish-blue scums or mats to form on the surfaces of streams, ponds, and lakes. These blooms may give off an unpleasant odor and can turn the water into different colors — green, brown, or even red.

The excessive algae growth can also cause an unhealthy increase in nutrients in a water body, a process called eutrophication. An abundance of nutrients may sound like a good thing, but eutrophication from fertilizer pollution in water upsets the delicate proportions of nutrients and disrupts the balance of plant life.

Eutrophication from synthetic fertilizer pollution has costly impacts on the environment and public health, such as the following:

Some harmful algal blooms release potent toxins into the water that can kill fish, shellfish, and even other plants, creating “dead zones” in the water.
Overgrowth of aquatic vegetation can clog waterways, restricting access to fishing, boating, swimming, and other recreational activities.
As excessive plant growth dies, its decay uses oxygen in the water. This can lead to “fish kills” – the death of large numbers of fish when oxygen levels drop too low for them to survive.
As oxygen levels drop and other conditions decline, the types of plants and animals that generally live in a waterway can change to less desirable ones. Essentially, where different species once existed harmoniously in an aquatic ecosystem, a single species may begin to dominate at the expense of all others.

Effects of Fertilizer Runoff on Human Health

If fertilizer runoff makes it into drinking water, it can have severe adverse effects on humans, especially babies, young children, pregnant women, and the elderly. As we mentioned earlier, nitrates are a common ingredient in fertilizer. But if you’ve read our article 5 Reasons to Avoid Nitrates in Water, you know the following health effects of nitrates:

They may be life-threatening to infants.

The health effects of nitrate in drinking water are most linked to methemoglobinemia, a condition known as “blue-baby syndrome.” In infants 0-4 months old, the nitrate is converted to nitrite in their digestive system. The nitrite binds to the red blood cells’ oxygen molecules, depleting the oxygen and potentially suffocating the baby.

A telltale symptom of nitrate poisoning is a bluish skin color, mainly around the eyes and mouth. If detected at such an early stage, methemoglobinemia is rarely fatal. It can be readily diagnosed and reversed with clinical treatment. After six months, methemoglobinemia is not a threat since the nitrate-converting bacteria are no longer present in the baby’s stomach.

They are linked to diabetes.

Studies found that nitrates may increase the risk of type 1 diabetes in children. It is believed that nitrates may lower the effectiveness of insulin in the body. If insulin isn’t doing its job, glucose builds up in the blood, resulting in hyperglycemia. If left untreated, another condition called ketoacidosis (diabetic coma) could occur.

According to the American Diabetes Association, ketoacidosis develops when the body lacks sufficient insulin. Without insulin, the body cannot use glucose for fuel, so the child’s body breaks down fats for energy. But how is this a bad thing?

When the infant’s body breaks down fats, waste products called ketones are produced. Their body cannot tolerate large amounts of ketones and will try to eliminate them through the urine. Unfortunately, the body cannot release all the ketones, which build up in the blood, leading to ketoacidosis. Symptoms of this condition may include shortness of breath, parched mouth, nausea and vomiting, and breath that smells fruity.

They may cause pancreatic cancer.

Nitrates and nitrites from processed meats, which are high in nitrates, are said to increase the risk of pancreatic cancer. When taken into the body, nitrate and nitrite can react with amines and amides to form N-nitroso compounds (NOC), which cause cancer in animals and may cause cancer in humans.

Studies have also shown an increased risk of kidney, colon, and stomach cancer among people who ingest high amounts of water containing nitrate and higher meat intake. Other studies have shown modest evidence that higher nitrate intake can increase thyroid cancer and ovarian cancer among women.

As we also mentioned earlier, fertilizer runoff may contain other potentially toxic elements, like bacteria (from sewage, dead animals, etc.), heavy metals (from rock and soil), and sediment, picked up as the water flows through different areas. All these elements can cause various health problems.

Learn more: Common Pathogens in Drinking Water and Their Potential Health Effects | Heavy Metals in Water & The Risk of Bioaccumulation

Tips to Help Prevent Fertilizer Runoff at Home

Are there ways to prevent fertilizer runoff from your lawn or garden? Absolutely! Try applying the tips below to reduce the effects of fertilizer runoff and minimize your yard and garden’s environmental impact:

Keep fertilizer away from water sources. When you apply fertilizer to your lawn or garden, ensure to keep it at least 20 feet away from nearby water sources. If your home overlooks a lake or you have a stream running through your property, keep your fertilizer well away from these areas to reduce the risk of nutrient pollution.
Let lawn clippings remain. When you mow your lawn, consider keeping the clippings there. As they decay, they return nutrients to the soil, reducing the need for fertilizer. They also help absorb water to prevent runoff. You can use a mulching mower to spread the clippings or detach the collection box from your lawn mower.
Use the correct type of fertilizer. When purchasing fertilizer, choose one that contains only the nutrients the soil needs. Starting with a soil test will help you understand those needs. Some states began banning the use of mineral phosphorus in fertilizer because of the harmful effects of eutrophication. Only fertilizers used for creating new lawns and gardens still contain phosphorous, but these are intended for short-term use only. Typically, enough phosphorus is already found in the soil that additions of the nutrient are never needed.
Apply the correct amount of fertilizer. Even with the right type of fertilizer, you must ensure you apply the right amount. Excess fertilizer in your lawn or garden increases the risk of runoff. Any remaining amount the soil doesn’t use will likely get washed away to nearby water sources during the next flood or heavy rainfall. A good rule of thumb for fertilizing a lawn or garden is to apply half a pound to a pound of nitrogen for every 1,000 square feet. You can tell how much of each nutrient you’re getting by looking at the numbers on the bag.
Consider applying mulch. When applying fertilizer in your garden, use mulch and layering to your advantage. Try spreading a layer of compost, applying fertilizer directly to the plant roots, then spreading a 2- or 3-inch layer of mulch over the top. The mulch will help retain soil moisture and keep fertilizer in place even during heavy rainfall.
Adjust your mower blade. Setting your mower blade to at least three high can help you reduce runoff in your yard. Taller grass absorbs more water and develops a more robust root system that can hold water and repel runoff. On top of that, a healthy root system withstands drought better. Therefore, you’ll need to water your lawn less often, which can further reduce the chance of runoff.
Use slow-release fertilizer. Although slow-release fertilizers with nitrogen are typically more expensive than quick-release synthetic fertilizers, they provide some excellent benefits, including more even, sustained grass growth (less mowing); and less leaching into ground and surface water. So, instead of dumping large amounts of chemicals into your garden or lawn all at once, slow-release fertilizer controls the nutrient release so that it remains low and constant throughout the growing season. As a result, the fertilizer will release nutrients when the grass is actively growing and can absorb them to prevent fertilizer runoff.

How to Protect Your Drinking Water from Fertilizer Runoff

Nitrates and phosphates in fertilizer runoff can significantly affect drinking water quality – and so can a host of other common pollutants, such as pathogens (bacteria, viruses, parasites, etc.), heavy metals (lead, copper, aluminum, etc.), and sediment (dirt, sand, debris, etc.).

At Springwell, the carbon filtration technology we use in our whole house water filters can help minimize concentrations of a wide array of contaminants, including pesticides, herbicides, haloacetic acids, chlorine, lead, mercury, volatile organic compounds (VOCs), sediment, and many more. For superior filtration, you can add our powerful UV water purification system to destroy up to 99.9% of harmful bacteria, viruses, parasites, and other nasty and unwanted microbes possibly in your water supply.

Reducing these contaminants results in cleaner, healthier, and safer water to drink and a great taste and smell that will make you want to stay hydrated all day. We also offer lifetime warranties on all parts, a six-month money-back guarantee, and state-of-the-art water filters and softeners proudly made in the United States.

Final Thoughts

Our nation’s waterways are brimming with excess nitrogen from fertilizer. And if we don’t take steps to reduce fertilizer runoff from our lawns, gardens, and crop fields, our drinking water quality and health could suffer. Let’s start by using the correct type and amount of fertilizer, setting our mower blades higher, applying mulch, and using slow-release fertilizers. It’s also vital to install a suitable water filtration system to remove nitrates, phosphates, and other potentially dangerous contaminants commonly found in fertilizer runoff. Doing so helps ensure your drinking water is fresher, tastier, and safe.