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Comparing Aquamation (Alkaline Hydrolysis) vs. Cremation: The Complete Guide

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Planning for end-of-life logistics is difficult. With newer concepts and options such as aquamation, planning requires thinking through many decisions about your preferences and how they will impact your family.

One of the single most important decisions you can make is choosing the method of final disposition. Historically this has been the choice between flame cremation and traditional burial. 

In the last few years, a new method of disposition called aquamation has become increasingly popular given its environmentally friendly nature. You may have also heard of this referred to as water burial or alkaline hydrolysis.

In this article, we’ll walk you through everything you need to know about aquamation; from its history, to the detailed process of how it works, and how you can learn more about it.

Aquamation Overview (Also known as Water Cremation)

Aquamation, (also known as alkaline hydrolysis, water cremation, or resomation) is a relatively new end-of-life process for the disposition of human remains that is becoming increasingly popular as an alternative to flame cremation.

The concept for alkaline hydrolysis originated in 1888 with Amos Herbert Hobson, who patented the process as a way to turn animal remains into a fertilizer for use as plant food.

It wasn’t until 2005 that the process started to be used for human disposition. The Mayo Clinic purchased the first alkaline hydrolysis system for human disposition. 

Similar to cremation, aquamation involves breaking down a human body into a powder. This means the remains do not have to be buried immediately, can be placed in an urn, and can be spread in various locations depending on the preferences of the family.

Instead of fire, aquamation relies on water with chemical compounds to break down the body.

Over the years, people from all over the world gave the process a few different names. Some of the most notable include:

  • Water cremation
  • Bio-cremation
  • Resomation
  • Flameless cremation
  • Green cremation

Although the interest in the concept has skyrocketed in recent years, it is currently only legal in about 20 states (except for pet aquamation which is legal in every state.) Archbishop Emeritus Desmond Tutu chose this eco-friendly alternative, and its popularity will continue to rise within the slow-moving funeral industry.

Resomation: An Eco-Friendly Alternative to Flame Cremation

The actual process of breaking down a human body via alkaline hydrolysis is a fairly simple procedure which we’ll detail below. However, the main difference with this eco-friendly alternative to flame cremation is that the hydrolysis process uses water instead of fire to accelerate the natural process of breaking a body down.

Read about common questions people have regarding aquamation to see if it’s the right choice for you.

Transporting the Body

Similar to flame-based cremation, the body needs to be transported to a funeral home where it can be prepared for its disposition and legal paperwork can be prepared. Be sure to call your local funeral home if you have questions on body disposal, traditional funerals, green burial, or other questions about the disposition of human remains.

Breaking Down the Body

To start the process, the body is placed in a stainless steel vessel and submerged in a solution of 95 percent water and 5 percent alkali. Usually, the alkali used is sodium hydroxide or potassium hydroxide. 

An alkaline hydrolysis machine used for water cremations
Photo courtesy of Pacific Interment, a partner offering water cremation services

The vessel is then pressurized and heated to a temperature between 320℉ and 350℉ which is used to accelerate the natural process of tissue breakdown. 

Due to the high pressure in the chamber, the liquid doesn’t boil. Instead, the solution will circulate around the body and will liquify everything except for the skeleton.

The alkaline hydrolysis process take from six to eight hours depending on the concentration of the hydroxide and the temperature.

At the start of the process, the pH inside the vessel is highly basic at around 14 as the alkalinity accelerates the natural decomposition of the body. B the end, the pH will drop a little and reach about 10 or 11 because of the solution of amino acids, peptides, sugars, and fats in the human body. 

Disposal of Waste Materials

What remains at the end of the process is a water-based alkaline solution and bones. In states where aquamation has been legalized, this solution has been deemed safe enough to be discharged into the city’s wastewater treatment cities.

Breaking Down the Bones

The alkaline solution is corrosive enough to break down muscles and soft tissue and they will be dissolved in water at the end of the process. The bones remain intact, but they become softened and brittle.

Similar to fire cremation, which also often leaves bone fragments, the remaining bones are crushed into a fine white powder. 

This powder is returned to the family in a container specific to the funeral home the family works with.

Aquamation Ashes vs Cremation Ashes

Alkaline Hydrolysis and Common Funeral Options

Given that the family is provided an urn filled with powdered remains, it is possible to have both normal funeral and interment ceremonies if you choose cremation.

You can have an urn with the water cremation remains in the front room of a funeral. For interment ceremonies, the remains can be spread somewhere meaningful like a cemetery or a vacation place.

This alternative to cremation and burial allows a family to have multiple options for interment in addition to a casket burial. 

If you are in a state that allows resomation, you can easily find a funeral home that can walk you through common funeral options for people who have chosen this method of body disposition.

Currently, aquamation is regulated and allowed in:

  • California
  • Florida
  • Idaho
  • Kansas
  • Maryland
  • Minnesota
  • North Carolina
  • Oregon

Pet Aquamation vs. Pet Cremation

Interestingly, the process known as aquamation is currently legal throughout the US for pets and is fairly common. The process is the same as it is for humans as heat, water, and alkalinity are used to accelerate the natural process of tissue hydrolysis.

Benefits of Aquamation

Many people believe that aquamation holds many advantages over cremation and traditional burial. The most popular reason is that alkaline hydrolysis uses 90% less energy than cremation (source).

The cremation process involves using two to three hours and more than 1,800 degrees of heat – enough energy to release 573 pounds of carbon dioxide into the atmosphere. Aquamation is an environmentally friendly process that has no associated emissions and the resulting liquid is safe enough to be released into the sewer system and processed by a local wastewater treatment facility. 

When it comes to a comparison with burial, it’s worthwhile to note that:

  • 800,000 gallons of formaldehyde are placed in the ground each year due to conventional burials as part of the embalming process
  • In just one year, the amount of casket wood buried is equivalent to about 4 million acres of forest
  • If you add up the square footage of all the cemeteries in the U.S. it measures 1 million acres of land
  • The process doesn’t require the use of flames. This means it is unnecessary to burn any fossil fuels to break down the body.
  • The lack of fire also means that the process won’t produce any harmful emissions or pollutants.
  • Alkaline hydrolysis uses much less energy and the pressure chamber can operate using a fraction of the power of a normal cremation.
  • The by-products of aquamation are all safe for the environment.

Lastly, since alkaline hydrolysis is a relatively gentle process, it results in a larger amount of ashes. This means that there is more ash to give to multiple family members if that is a consideration.

Aquamation Disadvantages

While there are many benefits to using aquamation, there are also a few disadvantages. For starters, resomation isn’t readily available across the US yet and many funeral homes in the United States are legally able to provide the service. 

The process requires special tools and equipment, like pressure chambers. Not all mortuaries will have access to the equipment, which means they can’t perform the process. Also, while the process produces a completely sterile mix of elements, human aquamation is a relatively new concept and there are no long-term studies on what the solution might do to the environment and the water table in particular.

Other than that, cultural acceptance may also be an issue. Some religions have an issue with aquamation as they require that the body is respectfully placed in the ground and they disagree with the body’s remains in the water solution put back into the sewer system. 

Finally, aquamation has only been around for a relatively short while. So, there are no long-term studies on the effect the process has on the environment.

Aquamation vs. Cremation

While the cremation rate continues to rise throughout the world, the majority of people who are considering aquamation (if it is available to them) are likely comparing it to cremation as an alternative. This section will compare the most common questions about each to give you an idea of which might be right for you.

Cost

The cost of aquamation can vary greatly depending on where you live given that the service is not as commoditized as cremation.

On average, however, alkaline hydrolysis can run you anywhere from $2,000 to $5,000.

A typical cremation will usually cost around $1,000 to $3,000 depending on the provider and any add-ons that you choose.

Duration

The process for both cremation and aquamation takes a relatively similar amount of time.

An average cremation can take about two to three hours depending on the size of the body. This is a relatively short time compared to aquamation.

As mentioned above, the aquamation process can take anywhere fr