Wildfires can contaminate nearby homes and water systems – here’s what returning residents need to k

When fire evacuation orders are lifted and residents start returning to burned neighborhoods, many people assume “” means “safe.” It rarely does.

As an who has worked with communities recovering from some of the in , I have seen the same pattern repeatedly: Families return to still-standing homes, turn on taps without knowing whether plumbing has been contaminated, and view debris removal as the end of recovery when it is often only the midpoint.

While there are , three deserve particular attention: chemicals in surviving buildings, the safety of drinking water and whether burned lots are ready for rebuilding.

A standing home is not automatically a safe home

Buildings that appear unscathed after a nearby fire may still be unsafe. Smoke, toxic ash and chemicals from burning buildings and vehicles can .

These contaminants settle in ductwork, walls, carpets and furniture, as well as on clothing, blankets and toys.

They can include , which can harm human lungs and children’s brain development; and , which can cause cancer and damage the respiratory system; and or organic compounds, known as VOCs, which can damage the organs; among other risks. Exposure to each through the air, food or drinking water can harm human health.

The home might seem fine, but contamination like this cannot be reliably identified by sight or smell. That’s why, before moving back into a home near where a wildfire burned, owners should consider , especially if part of the home or a .

Inspections should test living spaces, attics, crawlspaces, garages, HVAC systems, ductwork and indoor surfaces for harmful metals, chemicals and other substances. Dust is and other metals, as well as , while indoor air is often analyzed for volatile organic compounds.

The quality of the testing is critical.

Reviews of wildfire recovery efforts of inappropriate laboratory methods, incorrect comparison standards and results that could not be properly interpreted. Property owners should ask what contaminants will be tested, where samples will be collected, which analytical will be used, how results will be reported and when the report will be delivered.

If tests reveal contamination, remediation work comes next, followed by confirmation testing conducted by an independent firm. and workers restoring the site and safe practices to protect their health.

Do not assume the building’s water system is safe

Drinking water contamination is one of the least visible wildfire hazards. A functioning faucet can create a false sense of security.

Fires may damage water systems when firefighting demands and broken pipes cause the system to lose pressure. This can allow smoke, contaminated air or debris to enter pipe networks. Heat from a fire can also damage plastic pipes and plumbing equipment, releasing chemicals into the water supply.

Contaminants such as , which can cause cancer, have been detected in plumbing and water systems after fires at concentrations capable of causing illness through drinking, bathing or showering. Boiling water and may actually increase the chance people will be exposed to them by releasing them into indoor air.

A loss of water pressure, discolored water, melted plastic components or nearby fire damage can signal problems, but the contamination is often invisible, so testing is essential.

Utilities are generally responsible for and up to the property line and should provide public guidance on water safety.

Property owners are responsible for water safety once it enters the property. That includes pipes, water heaters, irrigation systems and . Even when utility water has been declared safe, contamination can .

Tests can look for volatile organic compounds, bacteria and, in some cases, semi-volatile compounds and metals. The samples for testing are commonly collected after water has been stagnant in plumbing for about 72 hours, allowing contaminants to accumulate. Depending on how the home was affected, residents may need to use alternative water sources such as bottled water for drinking, cooking and bathing.

require similar attention. Heat-damaged water tanks, troughs and irrigation lines , while smoke or ash can enter through vents. Repairs should be completed by licensed contractors and followed by disinfection and certified testing before the system returns to use. Local health departments have lists of approved water-testing laboratories.

Debris removal is a first step, not a finish line

Removing debris after wildfires burn through a property is only one phase of recovery, and it carries its own risks.

Effective restoration generally involves :

1. Removing major hazards, such as propane tanks, gas cylinders, batteries and damaged vehicles.
2. Removing debris, ash and contaminated surface soils.
3. . This final step is often overlooked.

A property is not necessarily safe to rebuild on simply because debris trucks are gone. Research after previous wildfires found that of properties still contained hazardous contamination, such as heavy metals, even after the debris had been removed and the topsoil scraped away.

To be safe, testing should be overseen by a or , independent of the debris-removal contractor. A notice that debris removal is complete indicates only that initial cleanup has ended. In many cases, local health departments or environmental agencies must review testing results before rebuilding can proceed.

The bottom line

While many hazards in the days and weeks after a wildfire are invisible, lessons from past events provide :

• Do not rely on appearance or odor to judge safety.
• Use qualified professionals to evaluate homes, water systems and soils before reoccupying or rebuilding.
• Consult local health departments for guidance and approved testing resources.

Restoring properties to safe use is possible. Following can help homeowners manage the process safely and with more certainty of a full recovery.