Climate change has made Earth-like Venus uninhabitable

Our tests have now confirmed a source of these chemicals and it is clear that wildfires are not the only flames that endanger drinking water systems.

In a new study, we heated plastic water pipes commonly used in buildings and water systems to test how they would respond to nearby fires.

The results, published on December 14, show how easily burns can cause widespread contamination of drinking water. They also show the risks when only part of the building catches fire and the rest remains in use. In some of our tests, heat exposure caused more than 100 chemicals to leak from the damaged plastics.

As environmental engineers, we advise communities on safe drinking water and disaster recovery. Extreme fire seasons in the western United States endanger many communities in ways they may not realize. This year, more than 52,000 fires destroyed more than 17,000 structures – many of them homes connected to water systems. Heat-damaged plastic pipes can continue to leak chemicals into the water over time, and removing a contamination water system can take months and millions of dollars.

A disconcerting source of contamination

The cause of drinking water contamination after wildfires has puzzled authorities since it was discovered in 2017.

After the 2017 Tubbs Fire and the 2018 Campfire, chemicals were found in buried water distribution networks, some at levels comparable to hazardous waste. Contamination was not found in water treatment plants or drinking water sources. Some homeowners have found contamination of drinking water in their plumbing.

Tests have shown that volatile organic compounds have reached levels that pose immediate health risks in some areas, including levels of benzene that have exceeded the EPA hazardous waste threshold of 500 parts per billion. Benzene has been found to be 8,000 times higher than the federal drinking water limit and 200 times the level that causes immediate health effects. These effects can include dizziness, headache, skin and throat irritation and even unconsciousness, among other risks.

Plastic water pipes should not burn to be a problem. Andrew Whelton / Purdue University, CC BY-ND

This year, wildfires have triggered drinking water contamination in at least two more drinking water systems in California, and testing is still ongoing in other communities.

The problem with plastics

Plastics are ubiquitous in drinking water systems. They are often less expensive to install than metal alternatives, which are resistant to high heat but are vulnerable to corrosion.

Today, water pipes under the street and those that deliver water to customers’ water meters are increasingly made of plastic. Pipes that carry drinking water from the meter to the building are often made of plastic. Water meters sometimes also contain plastics. Private wells can have plastic housings, as well as buried plastic pipes that deliver well water to storage tanks and buildings.

Pipes inside buildings that carry hot and cold water to taps can also be made of plastic, as can faucet connectors, water heater heating pipes, refrigerator and ice maker piping.

Some common types of drinking water pipes: Black plastic is HDPE; white is PVC; yellow is CPVC; red, brown, orange and blue are PEX; green is PP; and gray is polybutylene. Metal pipes are lead, iron and copper. Andrew Whelton / Purdue University, CC BY-ND

To determine whether plastic pipes could be responsible for contamination of drinking water after fires, we exposed the commonly available plastic pipes to heat. The temperatures were similar to the heat of a fire radiating to buildings, but not enough to cause the pipes to fire.

We tested several popular plastic drinking water pipes, including high density polyethylene (HDPE), crosslinked polyethylene (PEX), polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC).

Benzene and other chemicals were generated inside the plastic pipes only by heating. After the plastics cooled, these chemicals were then filtered into water. It happened at temperatures up to 392 degrees Fahrenheit. Fires can exceed 1,400 degrees.

While researchers previously found that plastics could release benzene and other chemicals into the air during heating, this new study shows that heat-damaged plastics can directly release dozens of toxic chemicals into the water.

What to do about contamination

A community can stop the spread of water contamination if damaged pipes can be quickly insulated. Without isolation, contaminated water can move to other parts of the water system, over the city or inside a building, causing additional contamination.

During the UDC Lightning Complex fire near Santa Cruz, a water supplier had valves in the water distribution system that appeared to contain water contaminated with benzene.

Rinsing damaged heat pipes will not always eliminate contamination. While helping Paradise, California, recover from the 2018 camp disaster, we and the U.S. Environmental Protection Agency estimated that some plastic pipes would require more than 100 days of continuous water rinsing to be safe. for use. Instead, officials decided to replace the pipes.

Different types of pipes respond to heating in different ways. Andrew Whelton / Purdue University, CC BY-ND

Even if a home is not damaged, we recommend that you test the water in the wells and private service lines if there has been a fire on the property. If contamination is found, we recommend that you find and remove sources of heat-damaged plastic contamination. Some plastics can slowly leach chemicals, such as benzene, over time, and this could continue for months or years, depending on the degree of contamination and water use. Boiling water does not help and can release benzene into the air.

Avoid widespread contamination

Communities can take steps to avoid contaminated drinking water in the event of a fire. Water companies can install mains isolation valves and backflow prevention devices to prevent contaminated water from moving from a damaged building to the utility pipeline network.

Insurance companies can use pricing to encourage homeowners and cities to install fire-resistant metal pipes instead of plastic. Rules for keeping vegetation away from meter boxes and buildings can also reduce the chance of heat reaching the plastic components of the water system.

Homeowners and communities rebuilding after fires now have more information about the risks as they consider whether to use plastic pipes. Some, like the city of Paradise, have chosen to rebuild with plastic and accept the risks. In 2020, the city had another fire scare, and residents were forced to evacuate again.

Andrew J. Whelton is an associate professor of civil, environmental and environmental engineering at Purdue University.

Amisha Shah is an assistant professor of civil engineering and ecological and environmental engineering, Purdue University.

Kristofer P. Isaacson is a doctor. Student, Purdue University.

Disclosure statement: Andrew J. Whelton received funding from the Paradise Irrigation District and the Paradise Rotary Foundation. He also participated in the California Governor’s Emergency Services Task Force in January 2019 through May 2019. Amisha Shah received funding from the Paradise Irrigation District. Kristofer P. Isaacson does not work, consult, hold shares, or receive funding from any company or organization that would benefit from this article, and has not disclosed any relevant affiliation beyond their academic appointment.

Reposted with permission from The Conversation.