Are your water pipes leaching toxic chemicals into your water? If your pipes are made of plastic, the answer is yes: they release chemicals such as bisphenol A and phtalates into the water. Studies show that these chemicals can lead to hormonal problems and chronic disease. Read on to learn about how plastic pipes affect the quality of your water, and what you can do about it.
Increasingly, water transport pipes are made of different types of plastic. The most widely used is PVC (polyvinyl chloride), as well as HDPE (high density polyethylene), PEX (cross-linked polyethylene), PEM (medium-density polyethylene) and PEL (low-density polyethylene).
Because plastic is cheap, durable, and chemically resistant to acids, alcohols and solvents, it is used in many industries. Since the 1960s, it has been the preferred material for water pipes, replacing those made of lead, concrete and cast iron. Unfortunately, we pay a price for this durability. Plastic leaches chemicals into the environment, including our water supplies.
When it became apparent that lead pipes contaminate water with toxic heavy metal residues, governments began replacing them with plastic pipes, believing these were safer. But studies have uncovered that plastic pipes also release harmful chemicals into the water.
Materials that are in contact with water usually end up transferring some of their components into the water (for example when pipes are made of lead or copper, a small amount of the metals end up in the water). That is the case with pipes made of plastic: they release polyvinyl chloride and other chemicals into the water.
A Danish study published in the journal Water Research examined three types of plastic commonly used for water pipes, and how these interact with water. The plastics were PEX (cross-linked polyethylene), PEM (medium-density polyethylene) and PEL (low-density polyethylene). The study found that each material leached between 20-30 different substances into the water, some of which were unidentified. In other words, there could even be unknown chemicals in your drinking water.
As early as 2003, research has shown that HDPE, PEX and PVC pipes released a number of volatile organic compounds into the water, including esters, aldehydes, aromatic hydrocarbons and terpenoids.
Other studies have demonstrated that plastic pipes release bisphenol A (BPA), nonylphenol and phthalates into the water. All three substances are endocrine disruptors, meaning they have a negative impact on hormones.
The chemicals that contaminate the water from plastic pipes are hormone-disrupting and cancer-causing. Let’s take a closer look at what science says.
Vinyl chloride has been classified by the IARC as a Group 1 carcinogen, meaning it is “carcinogenic to humans”. It has been linked to liver cancer, brain and lung cancers, lymphoma and leukaemia.
One of the phenols in PVC is 4-tert butylphenol. Lab tests show that it can cause reproductive abnormalities.
Phthalates, which are chemicals that are added to many plastics to make them more flexible, have come under fire for their negative effects. A review of studies published in the International Journal of Environmental Responsibility and Public Health finds that phthalates are linked to fertility disorders in men and women (such as lower sperm production and a higher risk of miscarriage), puberty abnormalities, and cancer.
Bisphenol A is also considered an endocrine disruptor and scientific studies have pointed to a link between exposure to bisphenol A and cancer, infertility, diabetes and obesity.
Hormones are vital for health – they are messenger chemicals that regulate many of the body’s vital functions (for example insulin, which tells the body to absorb and use glucose; or melatonin, which regulates your sleep-wake cycles; or sex hormones like testosterone and oestrogen, which can influence aspects of physical and mental health beyond reproduction). When hormones are disrupted, disease is not far behind. That’s why a group of almost 90 scientists from around the world has called for a boycott on the production and use of endocrine disruptors.
Their calls are being answered. Recently, the European Food Safety Authority (EFSA) proposed a 100,000-fold cut in bisphenol A. They set a new temporary tolerable daily intake (TDI) of 4 micrograms per kilogram of body weight per day (μg/kg bw/d), a considerable reduction from the earlier TDI of 50 μg/kg bw/d. The EFSA based this recommendation on studies showing that Bisphenol A has a negative impact on T-helper cells (white blood cells that have a key role in the immune system).
In an article entitled ‘Danger from the Tap’ by Algemeen Dagblad, Ana Soto, professor of cell biology at Tufts University in Boston, stated that the dangers of endocrine disruptors have been outlined for 15 years, but nothing has changed. Now it appears that these substances can end up in drinking water, but nobody knows how long governments will wait before taking action.
The longer the water is in contact with plastic pipes, the more chemicals leach into the water. Researcher Erik Arvin left water in plastic pipes for seven days to assess the impact. He found more than 20 chemicals that had leached into the water. Most of them were alkyl phenols, such as 4-tert butylphenol, and phthalates. According to Arvin, this happens mostly in and around the home. That’s because water in outdoor pipes (the main water network) is continuously on the move, whereas indoors it is often at a standstill for hours, or even days, waiting for a tap to be opened. The temperature is also often higher inside. These conditions make it more likely for the plastic chemicals to end up in the water. What’s more, the smaller the diameter of the pipe, the more contact there is between the water and the pipe, and this results in a higher degree of chemical leaching.
Arvin points out that only 10% of the chemicals have been identified. The other 90% remain a mystery – he doesn’t know what they are, nor whether they are harmful to health. Another thing that isn’t yet clear is whether these substances can enter the body via the skin, for example when showering. According to Ana Soto, this may be the case. She says that bisphenol A diglycidyl ester can penetrate the skin, and while we don’t yet know about other phenols, it is likely that phenols of a similar size can also enter the body through the skin.
Despite the debates, it is impossible to ignore the studies linking plastic by-products with health issues. According to a study published in the journal Environmental Toxicology and Pharmacology, polyvinyl chloride “is the most toxic polymer type”.
The latest Guidelines for Drinking Water Quality published by the World Health Organisation sets limits for some of the chemicals related to PVC, but not all.
The European Drinking Water Directive goes further on some of the chemicals, while being more relaxed on others:
According to the Dutch Water Supply Decree, the materials used for transporting water should adhere to strict rules. Article 17g reads:
“The owner ensures that the materials and chemicals used in the extraction, preparation, treatment, storage, transport or distribution of tap water and the way in which they are used do not lead to materials and chemicals:
a. remaining in the tap water in a higher concentration than is necessary for the use of those materials or chemicals; and
b. having adverse consequences for public health.”
This might, at first glance, appear to offer some protection, but some research points to the fact that plastic pipes do not comply with this legislation, particularly when it comes to public health.
Around 54% of the Dutch water pipe network (64,420 kilometres) is now made of PVC, while 25% of homes in the Netherlands have water pipes made of PVC or PE (polyethylene).
And this number is growing. PVC is cheap and durable, making it the preferred material for water pipes.
According to the French national regulations on the use of materials that come into contact with water, these should not pose any danger to health.
Article R.1321-48 stipulates that the materials and objects placed on the market and intended for production, distribution and packaging facilities which come into contact with water intended for human consumption must comply with specific provisions defined by order of the Minister responsible for health, designed to ensure that they are not likely, under normal or foreseeable conditions of use, to present a danger to human health or to cause an alteration in the composition of the water defined by reference to fixed values by this decree.
As we’ve seen, many studies show that plastic pipes are not compliant, as the chemicals they release in the water can have a negative impact on health.
Since the 60’s, PVC has been the preferred material for water pipes, replacing those made of lead, concrete and cast iron. Around 47% of France’s public water network (416,800 kilometres) is now made from PVC. Many houses in France, especially those built in the last 30 years, also have PVC or PE (polyethylene) water pipes.
In Italy, 25% of the public water network was laid over 50 years ago and is in urgent need of being updated. According to the National Statistic Institute, over 40% of the water transported by these pipes leaks during transit. In some cities, as much as 70% of the water is lost this way. The worst affected zones are Chieti, Sicily, and Basilicata.
The public water network is managed at a regional level, which makes the task of updating the pipes enormous and very slow. For this same reason, it is hard to know exactly which materials have been used for water pipes. The most common are cast iron, brass, copper and PVC. If you live in a house built in the last 30 years, there’s a high probability that your water pipes are in PVC or PE.
The public water supply network in Germany is 530,000 kilometres long. Polyethylene (PE) has been used as a water pipe material since the 60’s. Evaluations from 2015 show that around 20% of the network consists of pipes made of PE. According to Dr. Elmar Löckenhoff, former managing director of the German plastic pipe association e. V. (KRV), from the estimated average age of the pipes (35 years) we can conclude that polyethylene has become the standard pipe material in water supply. In 2015, 73% of the 16 million house connection lines were made of PE. When re-laying pipes, this plastic is the most chosen material.
The British drinking water legislation sets the following limit values in drinking water:
The UK has several materials approved for water pipes:
Most public water distribution pipes in the UK are made of blue polyethylene. In residential homes, PVC pipes have replaced copper pipes as the material of choice, due to their affordability and because they are easier to instal.
Ireland adheres the EU’s Drinking Water Directive and applies its limits for PVC and related chemicals.
A recent report by Irish Water shows that the water distribution network in Ireland is in poor condition and in urgent need of repair. Many of the cast iron pipes have significant rusting, and the PVC pipes laid in the 60’s and 70’s burst regularly. As a result, 49% of treated water is lost through leakage across the water network.
It is not known how much of the 112,372 kilometres of water pipes is made of PVC or PE pipes, but according to the Code of Practice for Water Infrastructure, the preferred materials for new pipes are polyethylene (PE) pipes and cement-coated cast iron pipes.
Over one million miles (1,609,344 kilometres) of PVC pipes are currently in service, representing around 78% of all new drinking water distribution pipes installed in North America.
The EPA has established the following maximum contaminant levels for plastic-related chemicals:
In February 2023, a train carrying hundreds of thousands of gallons of vinyl chloride derailed and crashed near the village of East Palestine in Ohio. In order to prevent the carriages from exploding, authorities decided to do a “controlled burn” of the chemical, which sent plumes of toxic smoke into the air. The chemicals also spilled into the Ohio river, causing fish and nearby wildlife to die, and contaminating drinking water supplies. Find out more here:
“If you have plastic pipes in your house, I strongly recommend that you let the water run for a while in the morning to get rid of water with a high concentration of chemicals,” Erik Arwin
Whether you have plastic pipes in your home or not, the chances are that your tap water has been through some of the PVC pipes in the public water distribution network. That means that it is likely to contain some of the chemicals mentioned in this article.
Several methods have been tested to eliminate BPA and other chemicals from water. These include reverse osmosis, carbon filtration, and biofilm reactors. The easiest way is to use a filter that’s proven to remove harmful chemicals from tap water.
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