Plastic water container type 7 (C) Daniel Friedman Plastic & Resin number code guide: Plastic Bottles, Containers, Tanks: Plastic Types, Plastic Contaminants

  • POST a QUESTION or READ FAQs about the different kinds of plastic used to make bottles and containers; how to identify different plastic types.

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What do the different recycling number codes on plastic products mean:

Here we provide a key to plastic resin identification codes and we provide photographs of the number codes, a description of the type of plastic each represents, and photos of typical plastic containers of each type.

Plastic bottles, containers, tanks: this article describes the types of plastics used in bottles, containers, and tanks, including for water storage, cisterns, and other liquids. We identify possible contaminants that may leach into drinking water from some types of plastic.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Types of Plastics Used for Bottles, Containers & Tanks

HDPE Plastic battery acid bottles, blue (C) Daniel Friedman

So What Plastic Was Used to Make My Water Bottle, Container, or Water Tank?

Image of plastic recycling code 7 (C) Daniel Friedman

How to Use the Plastic Recycling Code to Identify The Type of Plastic Tank or Container

How do you identify what kind of plastic was used to make your water or other storage tank or even your plastic water bottle or food container?

Use this simple guide to plastic recycling codes and look for the recycling indicator or label on your plastic container. Our photo (left) shows an image of the plastic recycling code #7.

Guide to Plastic & Resin Recycling Number Codes

Recycling code plastic type No. 1 PETE plastic symbol 1 (C) Daniel Friedman

#1 code plastics - PET / PETE (polyethylene terephthalate) One-time use (do not refill plastic water bottles carrying this recycling mark). See our plastic water storage tank, plastic Ethos water bottle photos and details below.

Very wide range of use for liquids, other. Household cleaners in clear bottles.

M&H Plastics points out that "PET containers require special consideration during warm weather in order to prevent shrinkage or distortion occurring after the molding process is completed." The company provides additional details including an interesting oxygen-scavenging PET innovation useful for packaging foods that deteriorate in the presence of oxygen.[10]

PETE plastic symbol 1 (C) Daniel Friedman
Recycling code plastic type No. 2 2 - HDPE plastic symbol 1 (C) Daniel Friedman

#2 code plastics - HDPE (high density polyethylene) (Nalgene Corp. produces HDPE water bottles) - also see PLASTIC & FIBERGLASS TANKS, HDPE

Very wide range of use for liquids, solids, pastes

BPA free water bottles (C) Daniel Friedman
Recycling code plastic type No. 3  

#3 number code plastics - PVC (polyvinyl chloride).

Watch out: a little confusing is that plastic bottle manufacturers may describe bottle categories as "PETG/PCTG/PVC bottles" [10]

Recycling code plastic type No. 4   #4 code plastics - LDPE (low density polyethylene  
Recycling code plastic type No. 5 5 Polypropylene  plastic symbol 1 (C) Daniel Friedman

#5 plastics - PP (polypropylene)

Typical examples: tan, translucent prescription bottles; plastic deodorant containers (shown at right)

5 Polypropylene  plastic symbol 1 (C) Daniel Friedman
Recycling code plastic type No. 6 Polystyrene coffee cup lid (C) Daniel Friedman

#6 plastics - PS (polystyrene) - example, white plastic coffee cup lid at left

Watch out: on some products the "6" plastic resin identification code may look like an "8" - not to worry, the plastic identification codes are numbers 1-7: if it looks like an "8" it's probably a "6".

Polystyrene coffee cup lid (C) Daniel Friedman
Recycling code plastic type No. 7 Image of plastic recycling code 7 (C) Daniel Friedman

#7 plastics - Plastics-other (includes polycarbonate plastics) 
(Nalgene Corp. produces lexan water bottles) - may leach BPA - Bisphenol-A (health concerns).

FYI: while BPA-containing plastic containers are expected to carry the #7 recycling label, according to the New York Times (7 Sept. 2010), not all plastics labeled with recycling symbol #7 are in fact BPA-containing.[7]

Watch out:On some containers it is tricky to distinguish between a "7" plastic code and a "1" PLASTIC CODE.

Plastic drinking water bottle, Ciel (C) Daniel Friedman


Key to Other Plastic Container & Packaging Abbreviations

Generally products made using plastics made of polymer chains that break down to become brittle in certain environments, such as under exposure to UV in sunlight, or under exposure to oxygen, typically within a 5-year time frame. Note that products that break down into tiny fragments are not in all cases environmentally sound - such as certain ultra-fine plastic fragments found in some ocean areas and on some coasts, and in seawater.
PCR Post-consumer regrind, recycled plastic products that are re-processed and re-used in manufacturing
PIR Post-industrial regrind, as above, but using plastic waste products recovered from industrial processes, often used to produce container caps and also some jars.
PLA Polylactic acid plastic products are plastic products made using corn starch rather than petroleum products as their chemical base

PET Plastic Water Storage Tank Health, Safety, & Sanitation Advice

Plastic water storage tank (C) Daniel FriedmanQuestion:

I've been unable to find on-line information about the safety of using common 1500 gallon plastic water tanks to hold drinking water. Our tank is shaded, but summers are warm and the water often sits in the tank for weeks, especially when we are traveling.

Our tank is 20 years old, but according to web sites now selling drinking water tanks, the plastic is polyethylene terephthalate aka PET.

To my knowledge, we haven't had any problems to date with bacteria growing. I don't taste plastic. We once had a mouse get in and die. Bad smelling water. It cleared up after a few weeks. Probably drank some of it!

Do you have any information or links? - Barbara Stuart

The above-ground water cistern storage tank shown in our photo (above left) is located in San Miguel de Allende, Mexico and is discussed at PASSIVE SOLAR HOME, LOW COST.


Plastic water bottle using PETE (C) Daniel FriedmanAs Ms. Stuart pointed out, some water storage tanks are made of plastic polyethylene terephthalate aka PET. Polyethylene Terephthalate (PET, PETE or polyester) is commonly used for carbonated beverage and water bottles intended for one time use - not a plastic one would expect use for a water storage tank.

But some water storage tanks have also been constructed of PETE material.

Our photo (left) illustrates a water bottle produced using polyethylene terephthalate.

PET - Polyethylene terephthalate (PETE, PETP, PET-P) is a thermoplastic polymer polyester plastic resin.

Plastic water tanks may be a health risk to consumers: Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research on this topic.

Proposed mechanisms include leaching of phthalates as well as leaching of antimony.

Other authors have published evidence indicating that it is quite unlikely that PET yields endocrine disruptors. - Web search 6/27/2010 Wikipedia. PET


Sorting Through the Confusion of Opinions vs. Studies About Plastic Container Materials, Names, Hazards

Plastic PETE designation (C) Daniel FriedmanResearching the health hazards of plastic containers and asking which plastics are safe can give conflicting and confusing results.

Our photo (left) provides a close-up of the #1 recycling code and the PETE indicator for polyethylene terephthalate embossed into the bottom of the plastic water bottle illustrated above.

Some sources such as the "green" website assert that PET or PETE polyethylene terephthalate and HDPE high density polyethylene plastic containers are "GOOD: Not known to leach any chemicals that are suspected of causing cancer or disrupting hormones.".

These same sources may tag LDPE, PP, PS as "OK", and tagging PVC or V and PS as "BAD - PVC - According to the National Institutes of Health, di-2-ethylhexyl phthalate (DEHP), commonly found in PVC, is a suspected human carcinogen., and BAD PS - According to the National Institutes of Health, di-2-ethylhexyl phthalate (DEHP), commonly found in PVC, is a suspected human carcinogen." - Web search 06/30/2010

There is also confusion about "polyethylene plastic" bottles and tanks. Don't confuse HDPE plastic (high density polyethylene) with PET - Polyethylene terephthalate (PETE, PETP, PET-P) - see What Plastic Was Used to Make My Water Tank (or water bottle)?

Looking at more expert researchers commenting on PET plastic containers:

But recently researchers have raised serious questions about potential health and environmental concerns for PET or PETE plastics. At Reviewers & References see Sax L 2010, López-Carrillo L, et als 2010, Koike E, 2010, for examples.

In April 2010 Environmental Health Perspectives, a peer-reviewed open access journal published by the National Institute of Environmental Health Sciences, Saxreported that

Polyethylene terephthalate (PET) is widely used to make clear plastic bottles for bottled water and containers for other beverages, condiments, and cosmetic products. There is concern that estrogenic chemicals such as phthalates may leach into the contents from bottles made from PET, although PET is not a phthalate derivative. Sax (p. 445) describes several studies suggesting that water from PET bottles can have estrogenic activity in some bioassays and that phthalates might leach from PET bottles.

The author notes the difficulties in evaluating these studies, especially in cases where there may have been prior contamination of the water or the containers with estrogenic agents or phthalates. Sax suggests that the phthalate content of PET bottles, if present, might vary as a function of the acidity of the product and the temperature and duration of storage. Sax also makes the observation that other nonphthalate chemicals such as antimony, which is used as a catalyst in the polycondensation of PET, might also contribute to the endocrine-disrupting activity of products stored in PET containers. The widespread use of PET plastic for a variety of applications suggests that additional research is needed.

The contents of the PET bottle, and the temperature at which it is stored, both appear to influence the rate and magnitude of leaching. Endocrine disruptors other than phthalates, specifically antimony, may also contribute to the endocrine-disrupting effect of water from PET containers.

Conclusions: More research is needed in order to clarify the mechanisms whereby beverages and condiments in PET containers may be contaminated by endocrine-disrupting chemicals.

If your water storage tank is made from Polyethylene terephthalate (PET), and is exposed to high temperatures such as exposure to direct sun and/or in a hot climate, the health risk may be increased. At REFERENCES, below, we include citations of several recent articles discussing health risks from Phthalates and PET containers.

Find Your Water Tank Plastic Type from the Manufacturer's Literature, Website, or Sales Support

Watch out: some plastic water storage tank distributors advertise that their tanks comply with some health and sanitation laws while omitting any comment about the type of plastic or possible PET concerns (see below). For example we found plastic water tanks advertised as

Specified IW series water tanks manufactured at Chem-Tainer's Compton, California factory are IAPMO certified to comply with the California Lead Plumbing Law and NSF/ ANSI 61- ANNEX G. This law states that any devices or components sold in the state of California that come in contact with potable water must comply with this law.

But it's easy to check the manufacturer's website or to ask the plastic water tank manufacturer for specifics of the plastics used. For example, Chem-Tainer Industries, a producer of a very wide range of plastic storage tanks indicates that

Chem-Tainer's fresh water tanks are an effective, economical way to store potable (drinking) water for Residential and Commercial applications. Our polyethylene resin complies with U.S. Food and Drug Administration regulation 21CFR 177.1520 (1) 3.1 and 3.2 for storage of potable water. These tanks are designed for water use only.

BPA - Bisphenol-A - containing Plastics: A Quick Summary on Endocrine Disruptors

BPA free water bottles for sale (C) Daniel FriedmanDetails about BPA plastics in food and liquid containers are found at Bisphenol-A, BPA. Excerpts are below.

According to the New York Times (7 Sept 2010)

Concerns about BPA stem from studies in lab animals and cell cultures showing that it can mimic the hormone estrogen. It is considered an "endocrine disruptor," a term applied to chemicals that can act like hormones. But whether it does any harm to people is unclear.

About half a dozen [U.S.] states have banned BPA in children's products ... This year a presidential panel on cancer and the environment said there was a "growing link" between BPA and several diseases, including cancer, and recommended ways to avoid BPA, like storing water in bottles free of it and not microwaving food in plastic containers. Some cancer experts said the report overstated the case against chemicals, but the concerns it raised seem to reflect growing public worries.


Continue reading at ENDOCRINE DISRUPTERS at BUILDINGS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Also see Bisphenol-A, BPA and PLASTIC & FIBERGLASS TANKS, HDPE and

see safety and health advice regarding cisterns and water storage tanks, including plastic water tanks, discussed at WATER TANK SAFETY

Other plastics used in construction that have been subject of failures and/or litigation: see PLASTIC PLEXVENT ULTRAVENT RECALL


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PLASTIC CONTAINERS, TANKS, TYPES at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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