What Is Alkaline Hydrolysis and How Does It Work?

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Alkaline hydrolysis, also known as water cremation, is a form of body disposition that uses a water and alkaline chemicals solution, heat, and other variables like pressure to reduce a human body. Alkaline hydrolysis offers some distinct "green" advantages over methods like burial and cremation and could one day become a significant body-disposition option.

Despite its advantages, alkaline hydrolysis will have to overcome certain obstacles before it will become mainstream, including public squeamishness and many regulatory hurdles.

This article discusses alkaline hydrolysis, how it works, and what some of its modern obstacles are.

Tombstones in a grassy field
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What Happens During the Alkaline Hydrolysis Process?

Alkaline hydrolysis uses water, potassium hydroxide (a common ingredient in liquid soap), relatively low heat (350 F/177 C) versus cremation, and pressure to reduce the body of a deceased loved one to bone fragments and an inert liquid. The process only works on protein-based materials, so the body must be dressed in certain types of natural-fiber clothing, such as silk, leather, or wool.

The body is next placed within a stainless-steel alkaline hydrolysis chamber. The entire process takes roughly two to three hours, which is equivalent to the time necessary for an average cremation.

Once alkaline hydrolysis is complete, the remaining bone fragments are rinsed and then pulverized to dust or "ash" (this also occurs with the bone fragments that remain after cremating a body). This dust can be returned to the surviving loved ones in an urn for placement in a cremation niche, scattering in a special place, burial, or any other option those choosing to cremate a loved one might select.

As noted earlier, the second byproduct of the alkaline hydrolysis process is an inert liquid, which does not contain human DNA or other genetic material. After filtering and purification at a water-treatment facility, this fluid can be introduced into Earth's natural water cycle.

The alkaline hydrolysis process is also called "water cremation" and Resomation and BioCremation (both trademarked terms). The general terms "flameless cremation," "chemical cremation," "green cremation," and "aquamation," are also sometimes used to describe the process.

How is alkaline hydrolysis different from cremation?

Traditional cremation uses a very hot fire to burn away tissue, leaving behind the bones, which are crushed and returned to the family as cremains. Water cremation uses a different process to remove the tissue, but it also leaves bones behind that can be crushed and returned as cremains. 

What Are the Pros of Alkaline Hydrolysis?

Compared to burial or cremation—the two typical forms of body disposition—alkaline hydrolysis offers several advantages in terms of ecological impact.

  • Less energy-intensive: Alkaline hydrolysis uses less energy compared to cremation, which relies on natural or propane gas to reduce a human body to bones through combustion.
  • Reduced emissions: Cremating a body creates carbon dioxide (CO2) emissions that can contribute to greenhouse gases. The high temperatures used to cremate a body will also vaporize tooth fillings that contain mercury, releasing harmful emissions into the atmosphere. The lower temperature of alkaline hydrolysis leaves fillings intact so they can be separated from the bone fragments before rinsing and pulverizing.
  • Reduced land use: Unlike traditional ground burial, the remains of the alkaline hydrolysis process reduce the demand on land space. Even if surviving loved ones choose to bury the remains in the ground, the amount of burial space necessary is significantly less than that of a traditional casketed burial.
  • It's a gentler process: Many people consider alkaline hydrolysis to be a gentler way to dispose of a body compared to cremation, which requires extremely hot (1400 to 1800F/760 to 982C) flames.

What Are the Disadvantages of Alkaline Hydrolysis?

Imagining a loved one reduced to "a green-brown liquid" can be a mental hurdle for some people when considering this form of body disposal. Even traditional cremation, which now accounts for the bodily disposition of around one in four U.S. citizens, faced decades of bias and rejection by funeral service practitioners and the public alike because it involved flames.

Fire cremation, however, is already a part of many cultural traditions and has become an accepted practice worldwide. For some people, the idea of a loved one's body leaving the Earth in the form of smoke can be seen as symbolic, especially in religions that believe that the spirit leaves the body in much the same way.

Cultural and religious traditions present a significant obstacle to the acceptance of water cremation since many cultures and religions have standard burial practices that outline the acceptable ways a body should be disposed of. Water cremation does not fit into many of these standards.

Other people prefer to imagine their loved one returning to the earth through the process of natural decomposition. These ideas about the "right" way to dispose of a person's remains may be a significant hurdle to newer, greener processes of body disposal such as alkaline hydrolysis.

Another tremendous obstacle alkaline hydrolysis must overcome is the regulatory morass governing the facilities that process dead bodies in the United States and worldwide. Any funeral home or crematory interested in adding alkaline hydrolysis to its services faces a multitude of regulatory hurdles. In the U.S., 20 states allow alkaline hydrolysis as of February 2020.

Summary

Alkaline hydrolysis—also called water cremation—is an alternative method of disposing of a human body. Because it uses water and lower temperatures than traditional cremation, it produces fewer emissions and is less energy-intensive than traditional cremation. Like traditional cremation, the cremains are returned to the family in the form of a powder, so it is also a way to reduce the land footprint of traditional burial.

Water cremation may have to overcome some religious and cultural obstacles before it becomes a standard practice. It is also only legal in less than half of the states in America and will have to overcome regulatory hurdles as well.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. O’Keeffe J. Alternative disposition services: Green burial, alkaline hydrolysis and human composting. Vancouver, BC: National Collaborating Centre for Environmental Health. 2023:2023-04.

  3. Cremation Association of North America. Alkaline Hydrolysis.

Chris Raymond

By Chris Raymond
Chris Raymond is an expert on funerals, grief, and end-of-life issues, as well as the former editor of the world’s most widely read magazine for funeral directors.