How Does a Body Decompose in Water: The Watery Graveyard

When a human body is submerged in water, it goes through a process of decomposition, just like in any other environment. Decomposition is the process by which organic matter breaks down into simpler substances, eventually becoming one with the environment. This process takes a significantly shorter amount of time in water, and it varies based on various factors. Some of these factors include the temperature, water salinity, water pH, and the surrounding organisms. As the body decomposes in water, various physical and chemical changes occur, which result in the deterioration and disintegration of the body tissues. In this article, we will go through the stages of decomposition and the important factors that affect the process.

The Stages of Decomposition in Water

Stage 1: The Fresh Stage

The fresh stage is the first stage of decomposition and typically lasts for the first few days after submersion. At this stage, the body appears fresh, with intact skin and no signs of decomposition. However, chemical reactions in the body have already started, and the body starts losing heat, which results in the cooling of surrounding water. Also, the body’s cellular activities cease, leading to the loss of normal body functions and the eventual death of the cells. At the end of the fresh stage, the body starts showing early signs of decomposition.

Stage 2: The Bloat Stage

The bloat stage follows the fresh stage and typically lasts for 3-5 days after submersion. In this stage, the body undergoes significant physical changes, leading to the accumulation of gas inside the body cavities. The production of gases causes the body to float on the surface of the water, making it easily visible. Also, at this stage, the signs of decomposition are highly visible, and the body releases strong odors that can be detected from a distance. Bloating can vary depending on several factors, such as the temperature, depth of the water, and water salinity.

Stage 3: The Active Decay Stage

The active decay stage follows the bloat stage and can last for weeks or months depending on the prevailing environmental conditions. During this stage, the body starts to break down extensively, and the tissue and organs undergo liquefaction. Insects, water organisms, and bacteria start feeding on the body, leading to the exposure of the bones, which are the only remaining parts after this stage ends. At this stage, the body starts sinking, and it is no longer visible on the water surface.

Stage 4: The Advanced Decay Stage

During the advanced decay stage, the major tissue decomposition has already occurred. Therefore, the body is mostly composed of bones, fur, or hair (if there is any). There is little to no odor, and the body is sometimes referred to as a “skeleton.” At this stage, scavenging animals may remove the bones if the bones are not protected.

Stage 5: The Skeletal Stage

The skeletal stage is the final stage of the decomposition process in the water. It occurs after the soft tissues have disappeared, and only hard tissues remain, covering bones, teeth, and nails. During this stage, there are scant remains of the body, and it is difficult to identify it. The duration of this stage depends on the environmental conditions and the composition of the body.

The Factors That Affect Decomposition in Water


The temperature of the water that a body is submerged determines the rate of decomposition. Warm water accelerates the process of decomposition. It speeds up the multiplication of bacteria and organisms that break down tissue, leading to a faster decomposition rate. Conversely, cold water slows down the rate of decomposition, as bacteria work at a slower pace. In cold water, the decomposition process can take a week or more longer.

Depth of Water

The depth of the water body affects the decomposition rate. If the body is in water that is too shallow or the water’s movement is very minimal, it will decompose faster because it is closer to the air. If the body is too deep, such as in the deep sea, the pressure crushes the body, slowing down decomposition. Also, the deep sea’s cold temperature, absence of light and oxygen, limit the activities of decomposing organisms, leading to slow decomposition.

Water Salinity

The level of salt concentration in the water affects the decomposition rate of a body. The higher the salt concentration, the slower the rate of decomposition. Saltwater gives off a toxic environment for decomposers, such as bacteria and insects, slowing down the decomposition rate. Freshwater has a lower salt concentration, promoting single-celled organisms and speeding up decomposition. Freshwater also causes bloating during the decomposition process, which is not possible in saltwater.

Water pH

The pH level of the water can either speed up or slow down the decomposition rate. The ideal pH range for bacterial growth is neutral between 6.5-7.5. Water environments that are too acidic, with a lower pH, hinder the growth of bacteria needed for decomposition, while very basic water (high pH value) kill bacteria, also interfering with decomposition.

Access to Oxygen

Oxygen access affects the rate of decomposition. In a water environment, access to oxygen is limited as water pressure increases with depth, reducing oxygen concentration. The decomposition rate in environments with low oxygen is slower. Oxygen accelerates the process of decomposition by providing microorganisms with enough energy for metabolism, enabling rapid multiplication and growth of bacteria and other decomposers.

The Role of Insects and Water Organisms in Decomposition

Decomposition is not only driven by natural chemical reactions but also by the activities of the insects and other organism feeds on the body tissue. These organisms’ speed up the breakdown of tissues and the consumption of the remains, hence accelerating the process of decomposition. Water organisms, including fish, crabs, and other aquatic animals, feed on the soft tissue of the body, with smaller insects and shellfish thriving on the skin and hair, whereas bigger organisms target the internal organs. These organisms begin breaking down the body’s soft tissues, and bacteria then take over the process, continuing the decomposition process.

The Challenges Associated with Investigating Underwater Decomposition

Investigating underwater decomposition is complicated by various factors. For instance, while the decomposition process in water is the same as that on land, there are significant differences in how the process occurs. This makes it challenging for forensic scientists and criminal investigators to decipher the sequence of events leading to a person’s cause of death. Factors like water body movement, weather fluctuations, and the presence of other aquatic creatures can interfere with the integrity of evidence, making it challenging to obtain accurate results.

The Bottom Line

Decomposition is a natural process that happens after death. Understanding the process is critical, particularly to forensic scientists, as it aids in identifying the cause and time of death. Decomposition in water is different than on land, but the process still follows the same stages of decomposition. The speed and duration of decomposition are affected by various factors, including temperature, depth of water, salinity, pH level, and access to oxygen.


  • Q: What is decomposition?

    A: Decomposition is the process by which organic matter breaks down into simpler substances, eventually becoming one with the environment.
  • Q: What are the stages of decomposition in water?

    A: The stages of decomposition in water include the fresh stage, bloat stage, active decay stage, advanced decay stage, and the skeletal stage.
  • Q: What factors affect decomposition in water?

    A: Temperature, depth of water, water salinity, water pH, and access to oxygen all affect the rate of decomposition in water.


  • De Haas, C., & Steel, K. (2013). The underwater environment: effects on postmortem interval estimation. Forensic science, medicine, and pathology, 9(4), 579-590.
  • Kauhanen, P. G., & Fornes, W. S. (1986). Aquatic decomposition: An overview. In Aquatic microbiology (pp. 191-215). Springer, Dordrecht.
  • Pokorný, P., Kuhtreiber, T., Velebil, D., & Znachor, P. (2016). Factors affecting the rate of carcass decomposition in water. Forensic Science International, 266, 240-244.

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