What the Number on Your Plastic Bottle Really Means

Plastic has quietly become one of the most pervasive exposures in modern life. It wraps our food, lines our supply chains, stores our water, and preserves the very products we use in the name of health. Yet convenience has come at a cost. Many plastics contain chemical additives such as plasticisers, stabilisers, and synthetic compounds that may migrate into food and beverages, particularly when exposed to heat or repeated use. Some of these substances have been studied for their ability to disrupt hormonal signalling in the body. In a world already burdened by endocrine stress, understanding our daily plastic exposure is no longer optional. It is a necessary part of preserving and maintaining your health.

What is even more confronting is that plastic is no longer just around us, it is within us. Microplastics have now been detected in drinking water, seafood, salt, soil, air, and even human blood and lung tissue. Research commissioned by the Worldwide Fund for Nature in 2019 estimated that the average person ingests up to five grams of plastic per week, roughly the weight of a credit card. While science continues to investigate the long-term implications, one fact is clear: plastic has moved through the supply chain and into the human body. Awareness is not about fear. It is about sovereignty. The more we understand where exposure occurs, the more empowered we are to reduce it.

A Simple Guide to Safer Water Storage

When buying bottled water, most people look at the brand, the price, or the source. Very few turn the bottle over and check the small recycling symbol on the bottom. Yet that tiny number inside the triangle can tell you a great deal about the type of plastic you are drinking from.

Plastic containers are labelled with resin identification codes from 1 to 7. These codes indicate the type of plastic used. Some are considered relatively stable for food and beverage use. Others are more controversial due to potential chemical migration, especially when exposed to heat, sunlight, or repeated use.

Understanding these codes helps you make more informed choices for your health.

1. PET or PETE (Polyethylene Terephthalate)

Common use: Single-use water bottles, soft drink bottles, some food packaging.

PET is one of the most widely used plastics in the beverage industry. It is lightweight, clear, and inexpensive. It is designed for single-use applications.

Repeated use, heat exposure, or long-term storage increases the risk of chemical migration and bacterial growth. PET is not intended to be reused, and it can be difficult to thoroughly sanitise.

Best practice: Use once, recycle, and avoid leaving in hot cars or direct sunlight.

2. HDPE (High-Density Polyethylene)

Common use: Milk jugs, detergent bottles, some water containers.

HDPE is considered one of the more stable and safer plastics for food and beverage storage. It has a strong structure and low risk of chemical leaching under normal conditions. It is also widely recycled and relatively simple to process into secondary products.

If glass is not available, HDPE is generally regarded as one of the better plastic options.

3. PVC (Polyvinyl Chloride)

Common use: Cling wrap, plumbing pipes, cable insulation, and some packaging.

PVC is a flexible plastic that contain additives such as plasticisers. PVC containers and packaging have raised health concerns due to chemical migration.

PVC is less commonly used for bottled water but may appear in other food-related packaging. Avoid use for food and beverage storage whenever possible.

4. LDPE (Low-Density Polyethylene)

Common use: Plastic bags, squeeze bottles, shrink wrap.

LDPE is generally considered low risk in terms of chemical migration. It is not typically used for rigid water bottles but is common in flexible packaging.

It is relatively stable but less commonly able to be recycled than HDPE meaning it typically ends up in landfills or being incinerated.

5. PP (Polypropylene)

Common use: Yoghurt containers, syrup bottles, bottle caps, food storage containers. Polypropylene is durable, lightweight, and heat resistant. It is widely used in food packaging and is generally considered a safer plastic option.

It resists moisture and many chemicals, which is why it is common in reusable food containers.

6. PS (Polystyrene)

Common use: Foam takeaway containers, disposable cups, packaging peanuts.

Polystyrene is lightweight and inexpensive but has raised concerns due to chemical migration, particularly when exposed to heat.

It is best avoided for all food and beverages.

7. Other (Including Polycarbonate)

This category includes various plastics that do not fall into categories 1–6. Some older polycarbonate plastics were made using BPA, a compound that has raised concerns due to its endocrine-disrupting potential.

Many manufacturers now produce BPA-free alternatives, but the number 7 category remains broad and inconsistent.

Practical Guidance for Health-Conscious Consumers

If your goal is to reduce chemical exposure:

• Choose glass whenever possible

• Stainless steel is excellent for reusable water storage

• If using plastic, opt for HDPE (2) or PP (5)

• NEVER reheat food or beverages in plastic irrespective of what type• Avoid where possible and NEVER reuse single-use PET bottles (pretty much all bottled water bottles)

• Avoid leaving plastic bottles in hot cars in storing in areas exposed to sunlight and heat

Heat, UV exposure, and repeated use increase the likelihood of material breakdown.

The Bigger Picture

Plastic is deeply embedded in modern life. While not all plastics carry equal risk, reducing dependency where possible supports both personal health and environmental wellbeing.

The safest long-term solution is not simply choosing a better plastic but reducing reliance on disposable materials altogether. Simple changes such as carrying a stainless-steel bottle or choosing glass storage can significantly lower exposure and reduce waste.

Small, consistent shifts create meaningful impact over time.

References

Cox KD, Covernton GA, Davies HL, et al. Human Consumption of Microplastics. Environmental Science & Technology. 2019;53(12):7068–7074.

Leslie HA, van Velzen MJM, Brandsma SH, et al. Discovery and quantification of plastic particle pollution in human blood. Environment International. 2022;163:107199.

Ragusa A, Svelato A, Santacroce C, et al. Plasticenta: First evidence of microplastics in human placenta. Environment International. 2021;146:106274.

World Wide Fund for Nature. No Plastic in Nature: Assessing Plastic Ingestion from Nature to People. 2019.

Rochman CM, Browne MA, Halpern BS, et al. Policy: Classify plastic waste as hazardous. Nature. 2013;494:169–171.