Climate change has made Earth-like Venus uninhabitable

Our tests have now confirmed a source of these chemicals and it is clear that fires are not the only fires that put drinking water systems at risk.

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 December 14, show how easily fires could trigger widespread contamination of drinking water. They also show the risks when only part of a building catches fire and the rest remains in use. In some of our tests, exposure to heat caused more than 100 chemicals to leach out of the damaged plastic.

As environmental engineers, we advise communities on drinking water safety and disaster recovery. The extreme wildfire seasons of the western United States are putting more communities at risk in ways they may not realize. This year alone, more than 52,000 fires have destroyed more than 17,000 structures, many of them connected to the water supply. Heat damaged plastic pipes can continue to leach chemicals into water over time, and clearing a water system of contamination can take months and millions of dollars.

A bewildering source of contamination

The cause of drinking water contamination following the fires has baffled authorities since it was discovered in 2017.

After the 2017 Tubbs Fire and 2018 Camp Fire, chemicals were found in underground water distribution networks, some at levels comparable to hazardous waste. The contamination was not in water treatment plants or drinking water sources. Some homeowners have found drinking water contamination in their pipes.

Tests revealed that volatile organic compounds had reached levels that posed immediate health risks in some areas, including benzene levels that exceeded the EPA’s hazardous waste threshold of 500 parts per billion. Benzene was found at a level 8,000 times the federal drinking water limit and 200 times the level that causes immediate health effects. Such effects can include dizziness, headache, skin and throat irritation, and even unconsciousness, among other risks.

Plastic water pipes don’t have to burn to be a problem. Andrew Whelton / Purdue University, CC BY-ND

This year, the fires triggered drinking water contamination in at least two other California drinking water systems, and trials are still ongoing in other communities.

The problem with plastic

Plastic is omnipresent in drinking water systems. They are often less expensive to install than metal alternatives, which resist high heat but are vulnerable to corrosion.

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

Pipes inside buildings that bring hot and cold water to taps can also be plastic, as can tap connectors, water heater immersion pipes, refrigerator and ice maker pipes.

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 the gray is polybutylene. The metal pipes are lead, iron and copper. Andrew Whelton / Purdue University, CC BY-ND

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

We have tested several common plastic drinking water pipes, including high-density polyethylene (HDPE), cross-linked 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 plastic cooled, these chemicals were filtered into the water. It happened in temperatures as low as 392 degrees Fahrenheit. Fires can exceed 1,400 degrees.

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

What to do in case of contamination

A community can prevent the spread of water contamination if damaged pipes can be quickly insulated. Without insulation, contaminated water can move to other parts of the water system, through the city or into a building, causing further contamination.

During the fire at the CZU lightning complex near Santa Cruz, a water utility had water distribution system valves that appeared to contain benzene-contaminated water.

Rinsing heat damaged pipes will not always remove contamination. As we helped Paradise, California recover from the 2018 Camp Fire disaster, we and the US Environmental Protection Agency estimated that some plastic pipes would take more than 100 days of non-stop water rinsing to be safe for use. . Instead, the 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, it is recommended to test the water in private wells and utility lines if the fire was on the property. If contamination is found, it is recommended that heat damaged plastic contamination sources be identified and removed. Some plastics can slowly leach chemicals such as benzene over time, and this could go on for months or years, depending on the scale of contamination and water use. Boiling the water doesn’t 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 network isolation valves and backflow prevention devices to prevent contaminated water from moving from a damaged building to the 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 got another scare and the inhabitants were forced to evacuate again.

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

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

Kristofer P. Isaacson is a Ph.D. Student, Purdue University.

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

Reprinted with permission from The Conversation.

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