The environmental concern over single-use plastic water bottles has led consumers to search for alternatives, with “biodegradable water” gaining traction. This term refers to the packaging, not the water itself. This article explores the materials used in this packaging, its environmental lifecycle, and what “biodegradable” truly means for sustainable hydration.
The Science of Water and Biodegradation
Biodegradation is a natural process where microorganisms like bacteria and fungi break down complex organic materials into simpler substances like carbon dioxide, water, and biomass. They secrete enzymes that break down large polymer chains into smaller pieces, which are then consumed for energy. This process requires a carbon-based structure that microorganisms can target.
Water (H2O) is an inorganic compound and does not biodegrade because it lacks this carbon structure. Instead of breaking down, water is recycled through the water cycle. This planetary-scale system involves physical changes like evaporation and condensation to purify and redistribute water. For this reason, the term “biodegradable water” refers to its packaging, not the water itself.
Materials in Biodegradable Water Packaging
Containers marketed as biodegradable are made from bioplastics, which are polymers from renewable biological sources. A common material is Polylactic Acid (PLA), a polyester created by fermenting plant starches from corn or sugarcane. The production process involves extracting the starch, converting it into sugar, and then fermenting it to produce lactic acid, which is then polymerized.
Another material is Polyhydroxyalkanoates (PHA). Unlike PLA, PHAs are produced directly by microorganisms. Certain types of bacteria create these polyesters as a form of energy storage, much like humans store fat. Scientists can cultivate these bacteria by feeding them organic materials, and then harvest the PHA polymers they produce.
Beyond PLA and PHA, researchers are exploring novel materials for water packaging. Examples include packaging made from seaweed, algae, or agricultural waste. These materials are sourced from fast-growing organisms or use leftover fibrous material to create durable containers.
The Environmental Reality of Biodegradable Plastics
The term “biodegradable” can be misleading because the end-of-life for these alternatives is complex. Most bioplastics, like PLA, require the specific conditions of an industrial composting facility to break down efficiently. These high temperatures, moisture levels, and microbial communities are not found in most natural environments.
When a biodegradable bottle ends up in a landfill, it is deprived of the oxygen needed for decomposition. In this anaerobic environment, it breaks down very slowly and can release methane, a potent greenhouse gas. In the ocean, the cold, low-oxygen conditions slow degradation, allowing it to persist and fragment into microplastics, similar to traditional plastics.
It is also important to distinguish between these commonly confused terms:
- Bio-based means the plastic is made from renewable resources, but does not guarantee it will biodegrade.
- Biodegradable implies the material can be broken down by microbes, but the timeframe and conditions are often unspecified.
- Compostable is a regulated term, indicating a material can break down into natural elements in a composting environment within a specific timeframe.
Sustainable Alternatives for Hydration
To reduce environmental impact, the best approach is to shift away from single-use containers. Reusable water bottles made from durable materials offer a long-term solution that curtails the cycle of production and disposal. Stainless steel bottles are a popular choice due to their longevity and inert nature, which prevents flavor transfer. Glass bottles are another option, valued for their recyclability and non-porous surface, though they are more fragile.
Beyond reusables, some single-use alternatives to plastic exist. Aluminum cans, for instance, are highly recyclable, with a significant percentage of all aluminum ever produced still in circulation today. However, the initial production of aluminum is an energy-intensive process that relies on mining bauxite ore.
Paper-based cartons are another alternative, but they present their own challenges. To hold liquid, they are lined with thin layers of plastic and sometimes aluminum, making them composite materials. This complex structure makes them difficult to recycle, as many facilities cannot separate the fused layers, often resulting in them being sent to landfills.