We think of cremation as a process involving fire, so the term ‘water cremation’ can be a puzzling one. We’re going to explain water cremation, or alkaline hydrolysis, on this page.

What is water cremation?

Water cremation is also called alkaline hydrolysis. It’s an alternative to burial or traditional cremation by fire. It occurs after a funeral, so the funeral service itself won’t be affected.

In alkaline hydrolysis, the body is placed in a ‘water chamber’ and broken down by a combination of water, heat and a strong alkali.

How does water cremation work?

Remember that you can skip this section if you might find the finer details distressing.

The chamber that the body is put into for a water cremation contains water mixed with a powerful alkali: potassium hydroxide, sodium hydroxide or a combination of the two. The liquid is heated past boiling point, but the pressure in the chamber prevents it from boiling.

This heated solution is powerful enough to dissolve the body’s tissues. You could think of it as speeding up the natural way a body breaks down during the years after death. It usually takes three to four hours.

The liquid will go through the usual water treatment processes and pass back into the water supply. It’s sterile, and the pH value is adjusted to a safe level before it’s drained.

After the process, the bones remain. These are powdered by a cremulator into an ‘ash’ that can be returned to the family, in the same way they would be after a traditional cremation.

From the perspective of those who survive, water cremation is similar to cremation by fire; the process takes place out of sight and the ashes are returned at the end, although the ashes from a water cremation are finer and whiter.

What are the advantages of water cremation?

Water cremation is often presented as a more environmentally friendly alternative to burial or cremation by fire. Burials create space concerns and can introduce contaminants into the soil. Traditional cremation uses a great deal of fuel and produces large quantities of carbon dioxide.

In an in-depth BBC article exploring the ‘what is alkaline hydrolysis?’ question, William Kremner mentions studies done by Dutch researcher Elisabeth Keijzer, which suggest that the environmental cost of water cremation is much smaller than that of burial or traditional cremation.

For many people, there’s an emotional element to deciding what should be done with their or a loved one’s body after death. For someone who loved water, or someone who was afraid of fire, a water cremation might seem more appealing than traditional cremation.


Is water cremation available in the UK?

Although water cremation isn’t banned by UK law, water cremation services aren’t yet available in the UK.

The alkaline hydrolysis process for humans is relatively recent. Before a facility can offer water cremation services, the local water treatment company needs to grant permission for alkaline hydrolysis to be used. Most UK water treatment companies haven’t yet given this permission, and no UK facilities currently offer the service.

Water cremation is currently used in a number of US states, and it’s possible that the UK will adopt it as an option in the near future.

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