Water Cremation: What the Evidence Shows

You will see several names for the same thing. The scholarly literature uses the technical term alkaline hydrolysis most consistently, while the funeral trade and the public use resomation (a trademark), aquamation, bio-cremation, flameless cremation, green cremation, and water reduction interchangeably^{[1, 2, 3]}. Recent UK academic writing treats "water cremation", "green cremation", and the trade names Resomation and Aquamation as synonyms for one process^[4]. So if a funeral director uses a word you have not heard, it is worth checking, but they are almost certainly describing the same method.

The body is placed in a sealed vessel with water and a strong alkali, either potassium hydroxide or sodium hydroxide, or a mix of the two. The solution is heated and, in the high-temperature systems used commercially, put under pressure. Reported operating ranges across the literature span roughly 98 to 160 degrees Celsius at 1 to 6 bar, which breaks the soft tissue down into a sterile liquid while leaving the brittle skeletal remains and any metal medical implants intact^{[3, 5]}. Lower-temperature and ambient designs also exist, trading speed for simpler infrastructure^[3].

Afterwards, the liquid is discharged to the sewer where local rules permit it, and the bone material is dried and mechanically ground in a cremulator, then returned to the family. People often call the result "bone ash", but the evidence is careful to point out that this is processed bone, not the ash of combustion, since nothing is burned^{[3, 6, 7]}. For a high-temperature system, the whole cycle takes in the region of six to eight hours^[5].

That is the part families ask about most, so it is worth saying plainly: what you get back is a container of pale, processed remains you can scatter, bury, or keep, in the same way as with flame cremation. The difference is in how the body is reduced, not in what is returned to you.

Water cremation is not a new or experimental idea. Alkaline hydrolysis was developed in the 1990s to dispose of animal carcasses, with one account tracing its use on human bodies donated to science to around 1995, and commercial funeral use beginning around 2011 when the first commercial Resomator was installed at a funeral home in St Petersburg, Florida^{[8, 9]}. It was first legalised for human use in the US state of Minnesota in 2003 and has spread state by state since, though it remains far less common than burial or flame cremation and continues to suffer from low public awareness^{[10, 11]}.

The engineering has kept developing. A 2025 study in Applied Thermal Engineering applied computer-based multiphysics modelling to a Resomation device's heat exchanger and cut its cooling time by 23 percent while reducing power use and carbon dioxide emissions by around 20 percent^[12]. That is the first structured engineering study aimed at improving the hardware, which had previously been designed largely by trial and error, and it is a reminder that the machines themselves are still improving.

This is where families most need the honest version, because the environmental argument is the main selling point in both trade and academic framing^[13], and it is also where the evidence is thinnest.

The headline claims are striking. Water cremation is widely reported to use around 85 percent less energy than flame cremation, or about a quarter of the energy, with a carbon footprint of roughly a quarter, no atmospheric emissions, and no release of mercury vapour from dental fillings^{[14, 15, 16, 17]}. Those numbers are plausible and consistent with how the process works. The important caveat is that most of them trace back to provider figures or secondary sources rather than to independent life-cycle assessments carried out by neutral researchers^{[13, 14]}.

For context, flame cremation runs at roughly 800 degrees Celsius for two hours or more and is estimated to emit somewhere in the region of 115 to 150 kilograms of carbon dioxide per body, along with nitrogen oxides, carbon monoxide, sulphur dioxide, particulates, mercury, other heavy metals, and persistent organic pollutants such as dioxins^{[10, 17]}. Burial carries a different burden: embalming chemicals such as formaldehyde, the timber and materials in coffins and vaults, the land taken out of use, and the possibility of soil and groundwater contamination from cemetery leachate^{[10, 17, 18]}.

Here is the single most important evidence gap. The strongest independent life-cycle assessment in this whole literature is a Dutch study, and it compared burial against flame cremation only, not water cremation. It found no significant difference across five environmental impact categories, with burial scoring lower in more than half of them but far higher in two, driven mainly by the contested question of how you count land use^[19]. No independent, full life-cycle assessment has yet compared alkaline hydrolysis directly against both burial and flame cremation across all impact categories. So the fair conclusion is that water cremation is very likely lower in energy and carbon than flame cremation and avoids its mercury problem, but a confident overall ranking against burial cannot be drawn from the current evidence. Anyone who gives you a precise "X percent greener than everything" figure is going beyond what the neutral research has established.

If the environmental case has a weak spot, it is not the carbon figures. It is the liquid the process leaves behind.

That liquid is consistently highly alkaline and organically strong, which is exactly why sewer authorities have been cautious about accepting it^[11]. Most of the hard data comes from studies of animal tissue and healthcare waste rather than human remains, but it points the same way. Animal-tissue effluents are brownish and gelatinous from dissolved collagen, with very high measured loads of organic carbon and oxygen demand^[20]. Healthcare-waste hydrolysis has produced effluent that exceeded discharge limits for acidity, nitrogen, and organic load, even where most other measures stayed within limits^[21]. A stronger alkaline mixture was classed as hazardous chiefly because of its very high alkalinity^[22].

This is not a reason to think the liquid is dangerous once handled properly. It is sterile, and it contains no DNA or pathogens. The point is that "discharge it to the drain" is a real regulatory question, not a formality. Where sewer discharge is not suitable, the research documents workable alternatives: neutralising the liquid, for example with acidic silage, followed by anaerobic digestion that reduced volatile solids by more than 96 percent, and co-composting with garden trimmings^{[23, 24]}.

This is precisely the issue that has slowed water cremation in England. An earlier West Midlands facility received planning permission but stalled in March 2017 when the local water company refused a trade-effluent permit, citing the absence of any water-industry standard for discharging liquefied human remains to the sewer^[25]. A Resomator unit has since been installed at Rowley Regis Crematorium, but the 2025 history of English cremation still flags the unresolved question of how to dispose of the effluent, "as it contains the last remains of a human body"^[26]. Whatever the marketing says, this is the practical hurdle any UK operator has to clear.

One claimed advantage of alkaline hydrolysis is that it destroys prions, the infectious proteins behind diseases such as CJD, which ordinary cremation does not reliably handle. The evidence here is more careful than the claim. When the European Food Safety Authority assessed an atmospheric-pressure hydrolysis method for high-risk animal by-products, it concluded that the available evidence did not demonstrate the required reduction in prion infectivity, so the method could not be treated as equivalent to the approved process^[27]. High-temperature, high-pressure systems may perform differently, but the biosecurity claim should be treated as method-specific rather than settled for every design.

The literature here is genuinely divided, mostly along religious lines, and the honest summary is that reasonable people disagree.

Catholic bioethics is split. One analysis argues that alkaline hydrolysis and cremation are not morally distinct at the level of the act itself, since neither is intrinsically wrong, yet still urges Catholic bodies to resist legalisation on grounds of human dignity and belief in bodily resurrection^{[28, 29]}. A secular ethical critique reaches the opposite conclusion, finding that water cremation "breaches no fundamental principles of respect for the deceased" and rejecting the common objections that it is unnatural, industrial, or merely waste disposal^[30]. Much of the public unease centres on the image of dissolving the body and releasing the liquid to the drain, a reaction reinforced by how the process has been portrayed on film and television, and by uncertainty about the wastewater^{[16, 11]}.

Formal guidance from UK faith communities is still limited because the option is so new. If faith or cultural tradition matters to your family, the sensible step is to speak to your religious leader directly rather than to assume the position, because for most communities this is unmapped ground.

Across the research, the thing holding water cremation back is not the science. It is cultural positioning and low public awareness^{[11, 43]}. Fieldwork in the US found that people who chose it were drawn by four things: a sense that it is environmental, gentle, water-based, and natural^[13]. Marketing research even found that the label "Bio-Cremation" tested as more meaningful to consumers than "Resomation" or "Aquamation", which tells you how much the framing matters^[3].

There is also a well-documented gap between what people say they want and what they choose. Studies of green funeral choices, including a survey of more than 600 Italian consumers across generations, find that intention is shaped by environmental concern, personal moral values, and a broader cultural shift, but that stated preferences often fail to translate into actual decisions^{[31, 32, 33]}. Water cremation is usually discussed alongside human composting as part of a wider "positive death" and eco-funeral movement^{[34, 35]}, and interest in it tends to run ahead of take-up.

Regulation is jurisdiction-specific and changing quickly, so any count of "how many places allow it" is out of date almost as soon as it is written.

In the United States, water cremation is authorised state by state, either by widening the legal definition of cremation to include chemical or thermal reduction, or by naming alkaline hydrolysis directly. The number of states allowing it has risen over time, from around 20 in 2020 to more than 20 by the mid-2020s with further legislation moving through, and adoption has been quicker in more liberal-leaning states^{[16, 36, 37]}. It is also reported to be legal in parts of Canada and Australia, and in New Zealand and Ireland, with Ireland reported as offering it as a European first^{[4, 38]}.

In the UK, the picture is that Scotland is the first UK nation to legislate for water cremation^[4], placing it within the existing framework of the Burial and Cremation (Scotland) Act 2016^[39]. The route ran through a package of consultations opened in 2023 and commencement regulations that followed^{[40, 41, 42]}. This matters because it fits the pattern seen elsewhere: in the US states, Canadian provinces, and Australian states where it is legal, water cremation is regulated as a form of cremation rather than as a wholly new category of disposal, the "cremation, only better" approach that the industry has promoted^[43]. Scotland has taken the same route. For the specific Scottish regulations, dates, and the practical timeline for facilities opening, see our water cremation for UK families guide, which tracks the current position.

In England and Wales, water cremation is not yet legal, but the Law Commission was asked in September 2024 to review burial, cremation, and other methods of disposal, and issued a consultation paper in October 2024^[26]. Scotland going first will provide real-world evidence about whether the effluent and regulatory questions can be handled in a UK setting. Northern Ireland would follow its own legislative process. None of this comes with a firm published timeline, so it is best understood as a matter of years rather than something imminent.

Because no Scottish provider has published prices yet, any figure is an estimate drawn from countries where the option already exists. On that basis, water cremation tends to sit between the cost of a direct cremation and a traditional cremation with a service, so as a rough guide you might expect a total somewhere in the region of £1,700 to £3,100 once a facility fee, funeral director's fees, and a biodegradable container are included. For comparison, a traditional cremation with a service commonly runs from about £2,100 to £3,600, a direct cremation with no service from roughly £740 to £1,600, and a burial with a service considerably more once a plot is counted. These are estimates, and the honest position is that UK pricing will only become clear once facilities are actually operating. Our guide on funeral costs sets out the full comparison, and our guide on green and woodland burials covers the other main low-impact option families ask about.

Pulling the evidence together, a few points hold up well. Water cremation is a chemically well-characterised, technically mature process. It is very likely lower in energy and carbon than flame cremation and avoids mercury emissions. Its principal open question is the high-strength alkaline liquid it produces and whether sewer systems will take it, which is a regulatory matter more than a technical one. Its main barriers are legal patchwork, some religious opposition, and low public awareness rather than any limitation of the method itself.

The biggest gap in the evidence is the absence of an independent, full life-cycle assessment comparing water cremation directly against both burial and flame cremation. Until that exists, the environmental case rests substantially on provider figures and on burial-versus-cremation studies that leave water cremation out. That does not make the greener claim wrong. It means the claim is reasonable but not yet independently proven, and it is fair for a family to weigh it as such.

If you are considering water cremation for yourself or someone who has died, the practical next step is a conversation with a funeral director about what is actually available where you are, and our companion guide on water cremation for UK families walks through that side in full.

Numbered in order of first appearance in the guide.

1. Robinson GM. Dying to go green: the introduction of resomation in the United Kingdom. Religions. 2021.
2. Krupar SR. Green death: sustainability and the administration of the dead. Cultural Geographies. 2017.
3. Olson PR. Flush and bone: funeralizing alkaline hydrolysis in the United States. Science, Technology, & Human Values. 2014.
4. Woodthorpe K, et al. Is human body disposal an environmental issue? Mortality. 2026.
5. Cirigliano D. A comparative analysis of contemporary methods of final disposition. Open Journal of Applied Sciences. 2024.
6. Osterholtz A. Bioarchaeology and social theory. 2025.
7. Untitled correspondence on resomation. BMJ. 2011.
8. Cann CK. Death and religion: the basics. 2023.
9. Knight H. Better ways to dispose of a body. New Scientist. 2011.
10. Slominski EM. Life of the death system: shifting regimes, evolving practices, and the rise of eco-funerals. Sustainability: Science, Practice and Policy. 2023.
11. Borgstrom E, et al. Critical approaches to death, dying and bereavement. 2024.
12. Nia BB, et al. A novel multiphysics-based analysis for performance enhancement of a heat exchanger in a Resomation device. Applied Thermal Engineering. 2025.
13. Robinson GM. Alkaline hydrolysis and its affordances. Mortality. 2025.
14. Dying arts. Chemistry & Industry. 2012.
15. Dying to be green. New Scientist. 2021.
16. Haneman VJ. Alkaline hydrolysis. SSRN Electronic Journal. 2021.
17. Lee K, et al. Energy saving and carbon neutrality in the funeral industry. Energies. 2022.
18. Franco DS, et al. The environmental pollution caused by cemeteries and cremations: a review. Chemosphere. 2022.
19. Keijzer E. The environmental impact of activities after life: life cycle assessment of funerals. The International Journal of Life Cycle Assessment. 2017.
20. Pinho S, et al. Effluents from alkaline hydrolysis of animal tissue. In: Wastes: Solutions, Treatments and Opportunities. 2015.
21. Pinho SC, et al. Characteristics of effluents from healthcare waste treatment with alkaline hydrolysis. Water and Environment Journal. 2016.
22. Pinho SC, et al. Effects of alkaline hydrolysis and autoclaving on inorganic components present in healthcare waste. International Journal of Environmental Science and Technology. 2014.
23. Arias JZ, et al. Ambient alkaline hydrolysis and anaerobic digestion as a mortality management strategy for whole poultry carcasses. Waste Management. 2018.
24. Das K. Co-composting of alkaline tissue digester effluent with yard trimmings. Waste Management. 2008.
25. Blaney I. The treatment of human remains under the ecclesiastical law of England. Ecclesiastical Law Journal. 2021.
26. Parsons B, et al. From dust to ashes: the development of cremation in England and Wales, 1874-2024. 2025.
27. EFSA Panel on Biological Hazards. Evaluation of an alkaline hydrolysis method under atmospheric pressure for Category 1 animal by-products. EFSA Journal. 2025.
28. Lasnoski KJ. Are cremation and alkaline hydrolysis morally distinct? The National Catholic Bioethics Quarterly. 2016.
29. Mirkes R. The mortuary science of alkaline hydrolysis. The National Catholic Bioethics Quarterly. 2008.
30. Scarre G. Alkaline hydrolysis and respect for the dead: an ethical critique. Mortality. 2024.
31. Nosi C, et al. Green funerals: technological innovations and societal shifts toward sustainable death care practices. Technological Forecasting and Social Change. 2024.
32. Nosi C, et al. Becoming a tree when I will be dead? Why not! Generation X, Y and Z, and innovative green death practices. Journal of Retailing and Consumer Services. 2023.
33. Villers S, et al. Dying to understand how historical trends and influential intermediaries impact the future of sustainable deathcare. Journal of Historical Research in Marketing. 2024.
34. Incorvaia AD. Death positivity in America: the movement, its history and literature. OMEGA - Journal of Death and Dying. 2022.
35. Rumble H, et al. Disposal or dispersal? Environmentalism and final treatment of the British dead. Mortality. 2014.
36. Slabbert M, et al. Aquamation: legal nail in burial and cremation's coffin? De Jure. 2021.
37. Olson PR. Domesticating deathcare: the women of the U.S. natural deathcare movement. Journal of Medical Humanities. 2016.
38. Pathak S, et al. Ritual ecologies: analyzing the environmental impact and cultural sustainability of death practices across civilizations. EPJ Web of Conferences. 2025.
39. Cranmer F. Parliamentary report. Ecclesiastical Law Journal. 2016.
40. Cranmer F. Parliamentary report, June to September 2023. Ecclesiastical Law Journal. 2024.
41. Cranmer F. Parliamentary report, October 2023 to January 2024. Ecclesiastical Law Journal. 2024.
42. Cranmer F. Scots criminal law: commencement of provisions of the Burial and Cremation (Scotland) Act 2016. 2026.
43. Arnold M, et al. Representing alkaline hydrolysis: a material-semiotic analysis of an alternative to burial and cremation. Mortality. 2023.