What Happens to the Body During Water Cremation — The Science Explained

The Chemistry in Plain Language

Alkaline hydrolysis — the technical name for aquamation or water cremation — is an accelerated version of the natural decomposition process. The same chemistry that breaks down organic tissue in soil over months or years happens in a controlled vessel over hours, using heated water and an alkaline solution.

The body is placed in a stainless steel pressure vessel filled with a solution of approximately 95% water and 5% potassium hydroxide (KOH) or sodium hydroxide (NaOH). Under heat, this alkaline solution breaks the chemical bonds in proteins and fats, converting soft tissue into its basic molecular components: amino acids, small sugars, salts, and soap molecules.

Bone is made of calcium phosphate — a mineral that isn't affected by the alkaline solution. It remains on a tray inside the vessel throughout the cycle, structurally intact.

Step by Step Through the Cycle

Preparation

The body is undressed (if not already) and placed in a biodegradable shroud or bio-bag made from starch or protein polymers. All synthetic materials — polyester, nylon, metal fasteners, plastic buttons — are removed because they don't dissolve in the solution and can clog the vessel's filtration system.

Natural animal-protein fibers like pure silk, wool, and leather dissolve completely during the cycle. Cotton and linen (plant-based cellulose fibers) don't dissolve cleanly and are also removed.

Medical implants are left in place unless the specific facility's protocol requires pre-removal. Pacemakers, orthopedic hardware, and dental amalgams are all safe at aquamation temperatures.

The Cycle

The vessel is sealed, and the solution is heated. Two system types are in commercial use:

High-temperature, high-pressure systems heat the solution to 300–320°F (150–160°C) under pressure. The cycle completes in 4–6 hours. These are common in facilities that handle high volume.

Low-temperature, atmospheric-pressure systems heat to 200–208°F (93–98°C) without added pressure. The cycle takes 12–16 hours. These are used by facilities that prioritize a gentler process or operate in jurisdictions where pressure-vessel regulations add complexity.

During the cycle, the alkaline solution progressively dissolves all soft tissue — muscle, fat, organs, skin, cartilage. The chemical bonds holding proteins together (peptide bonds) break under the combined action of the alkali and heat. Fats undergo saponification, converting into glycerol and soap.

By the end of the cycle, the only solid material remaining on the bone tray is the mineral skeleton — calcium phosphate bone fragments, clean and free of soft tissue.

Post-Processing

The bone fragments are removed from the vessel and transferred to a heated drying cabinet, where they dry for 24–48 hours. Thorough drying is critical — residual moisture sealed in a container will cause bacterial growth and odor over time.

Once dry, the bone fragments are processed in a cremulator — a mechanical pulverizer that reduces them to a fine, uniform powder. The result is a white to light tan, sand-like material that is the family's returned remains.

The liquid byproduct (hydrolysate) — containing the dissolved amino acids, sugars, salts, and soap — is discharged into the municipal wastewater treatment system, where it's processed alongside all other commercial and residential wastewater.

Recovery

Medical implants (titanium joints, surgical steel screws, pacemakers, dental amalgams) are recovered from the bone tray in clean condition. The alkaline solution doesn't corrode or warp these materials. The provider separates them from the bone fragments before cremulation.

Families can request the return of recovered implants. Some choose to keep them; others authorize the provider to send them to metal recycling programs.

What Makes It Different From Flame Cremation

The fundamental difference is temperature and mechanism. Flame cremation uses direct combustion at 1,400–1,800°F to reduce the body through burning. Aquamation uses chemistry at 200–320°F to dissolve tissue through the same alkaline reactions that occur naturally in soil.

Two practical consequences follow from this:

More remains are returned. The high heat of flame cremation burns away a significant portion of bone mineral. Aquamation's lower temperature preserves bone mass, producing 20–32% more remains by volume. Families typically need a 220–250 cubic inch urn rather than the standard 200.

Implants survive intact. Mercury from dental amalgams vaporizes at 674°F in a flame retort and exits through the stack. Pacemaker batteries can explode. Neither issue exists at aquamation temperatures. The listed implants come out clean and recoverable.

What the Process Is Not

Because aquamation is still unfamiliar to many people, misconceptions circulate — especially in online forums. A few clarifications:

The body is not "dissolved in acid." The solution is alkaline (basic on the pH scale), not acidic. KOH and NaOH are bases, the same class of chemicals used in soap manufacturing.

The process does not "flush the body down a drain." The liquid byproduct is a sterile solution of basic organic molecules. The remains returned to the family are the bone minerals — a separate material that never enters the wastewater system.

The remains are not "wet." Properly processed remains go through a dedicated 24–48 hour drying period before they're returned. They should be dry, fine, and free-flowing.

Understanding Before Deciding

The science of aquamation is straightforward, but the emotional weight of understanding it during active grief is not. Having a clear picture of the process — what happens, how long it takes, what comes back — lets families make the decision from knowledge rather than anxiety.

The Aquamation / Water Cremation Guide covers the full process in detail, with timeline trackers and provider comparison tools that translate this science into practical decision-making.