Top Risks of Using Municipal Waste as Lawn Fertilizer

Last Updated on July 10, 2025 by Brian Beck

Using municipal waste (often referred to as biosolids) for lawn fertilizer comes with some serious risks and trade-offs—despite being marketed as “recycled” or “sustainable.” Here’s a breakdown of the potential hazards:

⚠️ Top Risks of Using Municipal Waste as Lawn Fertilizer

1. Heavy Metal Contamination

Biosolids can contain lead, cadmium, mercury, arsenic, and chromium.
These metals accumulate in soil over time and cannot be broken down biologically.
They may leach into groundwater or be absorbed by plants, posing a health risk to pets, children, and local wildlife.

2. Persistent Organic Pollutants (POPs)

These include pharmaceuticals, hormones, flame retardants, and industrial chemicals.
Many of these compounds survive the wastewater treatment process and are highly resistant to decomposition.
POPs can interfere with soil microbiology, plant health, and even make their way into food chains.

3. Microplastics

Municipal waste is a huge source of microplastic pollution.
Plastics degrade into microscopic fragments that persist in the soil, altering soil structure and water-holding capacity.
Microplastics may also be ingested by microbes and worms, disrupting soil food web integrity.

4. Pathogen Survival

While treated to reduce pathogens, not all bacteria, viruses, and parasites are eliminated.
Some biosolids may still harbor E. coli, salmonella, or helminth eggs, especially in lower-grade composts.
This is a concern particularly on lawns where children or pets play.

5. High Salinity and pH Imbalances

Municipal waste-based fertilizers can contribute to salt build-up, making soils hydrophobic and stressing plants.
Some products also alter the pH, leading to nutrient lockout or biological dormancy in the soil.

6. Disruption of Soil Microbial Balance

The biological system in your soil relies on symbiotic microbes and fungi.
The addition of toxic residues from biosolids can suppress beneficial microbes, impairing nutrient cycling, disease resistance, and carbon storage.

7. Unknown Inputs

Municipal waste is a “mystery soup”—a catch-all for anything that goes down the drain.
This includes cleaning chemicals, industrial runoff, pharmaceuticals, and human waste.
There is little public transparency or consistency in what you’re actually putting on your lawn.

✅ Safe Alternatives

If you’re trying to improve soil fertility without the risks, consider:

Compost from clean organic sources
Vermicompost (worm castings)
Compost teas and biological inoculants
Mineral balancing based on a soil test
Carbon-based biological fertilizers (e.g., molasses, humates, kelp, fish hydrolysates)

🧠 Final Thought

Municipal waste may seem like a “free” or “green” option—but free often comes with invisible costs. In the pursuit of healthy, living soil, biosolids are a shortcut that undermines long-term fertility, biological integrity, and safety.