Why Water Makes Lithium Fires Worse
Your first instinct with any fire is to grab water. With lithium battery fires, that instinct can cause an explosion. Here is the chemistry, the exceptions, and what to do instead.
The Chemistry: What Happens
When a lithium-ion battery enters thermal runaway, the internal temperature exceeds 1,100 °F (600 °C). At these temperatures, applying water creates multiple dangerous reactions:
Steam Explosion Risk
Water contacting cells at 1,100 °F+ instantly vaporizes, creating rapid steam expansion. In an enclosed battery pack, this can rupture the casing and scatter burning debris.
Hydrogen Gas Generation
Water reacting with lithium metal (exposed in ruptured cells) produces lithium hydroxide and hydrogen gas. Hydrogen is explosive in concentrations as low as 4%.
Hydrofluoric Acid
The electrolyte in lithium-ion cells contains fluorinated compounds. When heated with water present, these can produce hydrofluoric acid — extremely corrosive and toxic even in small amounts.
Thermal Shock Spreading
Small amounts of water can crack adjacent cells through thermal shock, actually accelerating the cascade failure rather than stopping it.
Critical Distinction
Small amounts of water make things worse. Massive amounts of water (thousands of gallons) can cool cells below the thermal runaway threshold. This is why firefighters use continuous water streams for 30–60 minutes on EV fires — but that is not something a homeowner can replicate.
How Firefighters Handle It
Fire departments have evolved their approach to lithium battery fires significantly:
- 1Continuous water application — 3,000–8,000+ gallons applied over 30–60 minutes to cool cells below the 300 °F threshold where thermal runaway sustains.
- 2Thermal imaging — monitoring individual cell temperatures to confirm runaway has stopped.
- 3Extended monitoring — watching for reignition for up to 24 hours. Some departments submerge battery packs in water-filled dumpsters.
The key insight: water can work on lithium fires, but only in quantities and durations that are impossible for consumers to achieve.
What to Use Instead
For consumer use, your best option is to suppress the surrounding fire (materials ignited by the battery) while accepting that the battery itself will burn until the cells are exhausted or cooled by firefighters.
ABC Dry Chemical
Suppress surrounding flames. Will not stop thermal runaway but limits fire spread.
AVD (Aqueous Vermiculite Dispersion)
Best consumer option for direct battery fire. Encapsulates and cools.
Water (garden hose)
Only if no electrical hazard and you have massive continuous supply. Generally avoid.
Water (cup or bucket)
Never. Insufficient volume causes all the problems listed above.
For a full comparison of what works on lithium fires, see ourCertification Decoderand the NTA 8133 guide.