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Can Human Waste Be Used As Fertilizer Safely?

Human waste, often referred to as “night soil,” has been used as a fertilizer in various cultures throughout history. However, in contemporary society, the topic often stirs discomfort due to both social stigma and public health concerns.

However, as an experienced expert in the field of sustainable agriculture and waste management, I believe it’s time to revisit this topic with a fresh perspective when things like the Solar Punk movement have been gaining traction in different places around the world.

tl;dr: Human waste can indeed be used as a fertilizer. The key, however, lies in its proper treatment to eradicate pathogens. When appropriately treated, human waste – or biosolids – can provide a rich source of nutrients for plants and contribute to sustainable agriculture practices. However, it’s not a simple do-it-yourself project, and regulatory guidelines should be followed to ensure safety.

Here’s the general overview of what you need to know

Pros Cons
Rich in essential plant nutrients such as nitrogen, phosphorus, and potassium. Requires a complex and strictly regulated treatment process to ensure safety.
Contributes to the sustainability of agriculture by closing the nutrient loop. Can contain potential contaminants such as pharmaceuticals and other synthetic compounds.
Helps reduce dependency on chemical fertilizers, which can have harmful environmental impacts. There is a significant social stigma associated with the use of human waste in agriculture.
Potential waste management solution, reducing the amount of waste that ends up in landfills or water bodies. Risk of pathogen transmission if not treated correctly.
Reduced cost in the long run, as waste is converted into a resource. Limited applicability in some areas due to regulatory constraints or lack of infrastructure.

The Potential of Human Waste as Fertilizer

Human waste, when properly treated and composted, can serve as a nutrient-rich fertilizer. The waste we produce contains essential nutrients like nitrogen, phosphorous, and potassium, which are vital for plant growth.

While many of us are aware of the natural nutrient cycle in which animals consume plants and excrete waste, few are comfortable with the idea of reintegrating human waste back into the cycle. It’s important to consider that, if treated correctly, using human waste as fertilizer could help close the nutrient loop, conserving resources and potentially reducing our dependency on chemical fertilizers.

However, the key here is proper treatment. Raw human waste is a hotbed for a wide array of pathogens and harmful bacteria that could pose serious health risks. Thus, a comprehensive treatment process is indispensable to ensure safe usage.

The Treatment Process: From Waste to Fertilizer

There is a well-established process for converting human waste into a safe, usable fertilizer, often referred to as biosolids. Here is a step-by-step guide to the transformation:

  1. Collection: The process begins at the wastewater treatment plant, where sewage is collected from various sources.
  2. Primary Treatment: The incoming sewage undergoes primary treatment to separate solid waste from liquid. This includes a process known as sedimentation, where the heavier waste settles at the bottom of the tanks.
  3. Secondary Treatment: The solid waste, or sludge, then undergoes secondary treatment where it is further broken down through biological processes.
  4. Sludge Thickening and Dewatering: The treated sludge is then thickened and dewatered to reduce its volume and water content.
  5. Pathogen Elimination: The sludge is then heated to a high temperature to eliminate harmful pathogens, making it safe for use as a fertilizer.
  6. Conversion into Biosolids: The end product of this rigorous process is known as biosolids, which can be used as fertilizer.

Remember, this process requires specialized equipment and knowledge, and it’s not something that can be conducted at an individual or household level. But understanding this process highlights the potential that human waste can have when converted into biosolids.

Proper Ways To Use Human Waste As Fertilizer

Using human waste as fertilizer has been done for centuries. It is an excellent source of fertilizer for plants.

There are proper ways to use human excreta without causing harm to plants or people.

Compost: The most common method is to compost it. Composting human waste is a great way to reduce the amount of waste that goes to landfills. There are three ways to carry out this process, namely:

Cold Composting: Cold composting is by adding human waste to a compost bin or pile along with other organic matter, such as leaves and grass clippings. The bin needs regular turning to help speed up the composting process. This process takes months to destroy the pathogens. Once it’s completely broken down, you can use them in gardens and other plantings. Thus, the product is known as biosolids.

Hot Composting: Hot composting is the process of composting human waste at high temperatures to kill pathogens. The process typically involves raising the compost pile temperature to 60 and 70 degrees Celsius for at least three days. Some hot composting systems also use additional methods to ensure that the compost pile reaches the desired temperature, such as insulating the compost or using forced air circulation. It is an effective way to compost human waste because it kills pathogens that can cause disease and is also effective in breaking down waste in large volumes for a relatively short time. However, hot composting systems can be expensive to build and operate and requires careful management to maintain the desired composting temperature.

Vermicompost: Another best method for using human waste as fertilizer is in a worm bin. Worms consume the waste and turn it into vermicompost, an excellent fertilizer. This method is the best if you have limited space because worm bins can be small and compact.

Humanure: Another way to use human waste as fertilizer is to mix it with water and apply it directly to plants. This is called humanure and It is often mixed with urine, which is high in nitrogen. To do this, urine is added to a bucket or other water container and allowed to decompose for several weeks. The water is then diluted and applied to plants. But when applying it to the soil, you should be careful because it can contain harmful bacteria.

Crops Grown Using Human Waste

In recent years, there has been an increase in farms growing crops using human waste. The waste is used as a natural fertilizer and helps improve the quality of the soil. Crops grown using human waste are often known as sewage sludge crops.

Sewage sludge is the solid waste produced when the sewage is treated at a wastewater treatment plant. The crops grown using this method are often more nutritious and yield better than the ones cultivated using traditional methods.

Examples are:

  • Corn
  • Wheat
  • Soybeans
  • Fruits and vegetables.

These crops grow well because the excreta contains nitrogen and phosphorus.

Countries That Have Used It

It’s no longer surprising some countries use human excreta in agricultural fields.

They collect and treat fecal sludge to improve soil fertility and increase crop yields.

The countries are:

  • China
  • Australia
  • Netherlands
  • USA
  • India
  • United Kingdom
  • Japan
  • Vietnam
  • North Korea
  • Sweden, etc.

In addition, many Sub-Saharan African nations use human excreta for agricultural purposes.

The Pros Of Using Human Waste As Fertilizer

Below are some pros to growing crops using human waste.

  • Human waste is a natural source of nutrients and minerals that can help promote plant growth.
  • Human waste can also help improve soil structure and increase water retention, making it an ideal option for farmers and gardeners looking to improve their yield.
  • Using human feces as fertilizer can help to reduce greenhouse gas emissions and the amount of waste that goes to landfills.
  • It is a renewable resource, making it a sustainable option for fertilizer.
  • Additionally, human excreta is more environmentally friendly.

The Drawbacks Of Using Human Waste

While human waste can be an effective fertilizer, it can also pose risks to public health if treated wrongly.

  • Human waste can contain harmful bacteria and viruses that cause illnesses and diseases.
  • It can contain toxic chemicals that can contaminate the soil and water.
  • While some treatment options are available to make human feces safe, these treatments can be expensive and may not be available in all areas.
  • Another potential con is the smell: Human waste can be very smelly.When it’s not well-treated, the odor will cause some health challenges.
  • Finally, human waste can contain toxins that could potentially harm plants or animals that come into contact with it.

Caution: You should apply human waste in moderation.

Too much can harm plants and the environment. It is best to consult with a local expert to determine the quantity your soil can safely handle.

Other Considerations and Alternatives

While the potential benefits are compelling, it’s also important to consider the potential downsides and alternatives. As an expert, I recommend weighing these considerations before jumping onto the biosolid bandwagon:

  • Regulation Compliance: The production and use of biosolids are regulated by strict environmental and health guidelines. Any attempt to repurpose human waste as fertilizer must adhere to these guidelines to ensure public safety.
  • Social Acceptability: There is still a significant ‘yuck’ factor associated with the use of human waste as fertilizer. Acceptance of this practice will require widespread education and openness to unconventional ideas.
  • Potential Contaminants: Human waste can contain traces of pharmaceuticals and other synthetic compounds that could potentially find their way into the food chain.
  • Alternatives: If you’re not quite ready to embrace biosolids, consider other organic fertilizers. Composting kitchen waste, manure, or using green manure and cover crops are excellent ways to enrich your soil organically.

The Nutrient Cycle: Closing the Loop

To better understand the concept of using human waste as fertilizer, it’s worthwhile to understand the nutrient cycle. In nature, nutrients constantly move in a cycle from the atmosphere and soil to plants, then to animals, and back again.

When we eat food, our bodies extract nutrients, and the remaining waste material is rich in these nutrients. By using human waste as fertilizer, we’re essentially returning these nutrients back to the soil, helping to ‘close the loop’ in the nutrient cycle. This sustainable approach to nutrient management could be a significant step toward resource conservation and sustainability.

The Science Behind Pathogen Elimination

In the treatment of human waste to create biosolids, one of the most critical steps is the elimination of harmful pathogens. This is achieved through a process called ‘digestion,’ where the waste material is heated to high temperatures to kill disease-causing bacteria, viruses, and parasites.

The sludge is typically heated to temperatures above 55 degrees Celsius (131 degrees Fahrenheit) for a specified period, a process that is governed by strict regulations to ensure safety. This process is crucial to convert potentially harmful human waste into a safe and nutrient-rich biosolid.

The Environmental and Social Implications of Biosolids

Discussing the broader implications can make the article more engaging. For instance, biosolids can reduce reliance on chemical fertilizers, which have detrimental environmental impacts such as nutrient runoff leading to water pollution.

Moreover, highlighting success stories or case studies where communities have successfully adopted the use of biosolids can make the concept more relatable. Discuss the challenges faced, how they were overcome, and the benefits reaped.

Additionally, include information about ongoing research in this field. For instance, scientists are exploring advanced treatment processes that can eliminate emerging concerns such as pharmaceutical residues in biosolids. Discussing ongoing research can indicate that the field is active and evolving, and spark interest in readers to follow and learn more about these developments.

By incorporating these additional aspects, you’d be adding a scientific dimension to the article, making it more informative while maintaining an engaging tone.


While the thought of using human waste as fertilizer may seem odd or even off-putting, it is, in fact, a practice rooted in circular economy principles. If we can overcome the stigma and harness this resource safely and effectively, we could take a significant step towards sustainable agriculture. But it’s not a task for the untrained. Proper treatment is crucial, as is adherence to regulations and guidelines.

Using human waste as fertilizer is not a silver bullet for our waste management and agricultural challenges. Still, it’s an option worth exploring as we search for sustainable and resource-efficient solutions in a rapidly changing world.


Is it safe to use human waste as fertilizer?

Yes, but only after it has been properly treated to eliminate pathogens and harmful bacteria. This is typically done at wastewater treatment facilities and is not a DIY process.

Are there regulations for using human waste as fertilizer?

Yes. In the United States, for example, the EPA has strict guidelines on the treatment and use of biosolids to protect public health and the environment.

Can I compost human waste at home?

In general, composting human waste at home is not recommended due to the risk of pathogens. If you are interested in composting waste, stick to compostable household items like fruit and vegetable scraps, coffee grounds, and yard waste.

Are there alternatives to using human waste as fertilizer?

Yes, there are many other types of organic fertilizers you can use. These include composted kitchen waste, manure, green manure, and cover crops. Each of these options is safe and can contribute to the health and productivity of your soil


  • Jen Wheeler

    Jen Wheeler, co-founder of Recycling-Revolution.com, holds degrees from UC Berkeley, Yale, and Stanford. A renowned environmentalist, she's championed sustainable practices at global events and leads EcoBright Solutions, focusing on recycling education and eco-friendly products.

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