Is It Safe to Store Windshield Washer Fluid in the Trunk?

[DominicAnn]

Storing windshield washer fluid in the trunk is safe, as it is not prone to evaporation. However, ensure the cap is tightly secured. Windshield washer fluid is a liquid used to clean the vehicle's windshield and is considered a consumable item in automotive use. The functions of windshield washer fluid include: 1. Maintaining the transparency of the front windshield while driving; 2. Extending the lifespan of the windshield and wiper blades; 3. Preventing window icing in winter; 4. Reducing static electricity on the windshield. The steps to add windshield washer fluid are: 1. Turn on the wiper switch, and the fluid will spray from below the windshield; 2. Continue until the spray nozzles stop emitting fluid, then open the washer fluid filler cap and add the fluid; 3. Turn on the wiper switch again to clear any remaining fluid; 4. When no more fluid sprays out, add the washer fluid and securely close the cap.

[OReid]

I usually keep windshield washer fluid in the trunk for years without issues, but one summer when parked outdoors in extreme heat, the trunk became like a steamer—the bottle swelled up and nearly leaked. Since then, I wrap it tightly in a sealed bag and place it securely in a corner to prevent leaks while keeping it accessible. Windshield fluid is mainly water and detergent, so it generally won’t ignite, but leakage could corrode trunk carpeting or stain items. Extra caution is needed in winter, as sub-zero temperatures may freeze and crack the bottle, creating a mess. Overall, trunks aren’t ideal for chemicals, but with sturdy bottles, secure placement, and regular checks on cap tightness, safety is manageable. Still, it’s better to minimize storage or keep it in the garage to avoid trouble.

[LaWalter]

Windshield washer fluid contains solvents and additives, and storing it in the trunk is generally safe. However, trunk temperatures can fluctuate significantly—summer exposure can exceed 50°C, causing bottle deformation or ingredient degradation, increasing the risk of leakage. Prolonged exposure may also produce pungent odors, affecting cabin air quality. I recommend choosing tightly sealed bottles, placing them in a cool corner to prevent shaking, and taking precautions against freezing in winter. Additionally, while windshield washer fluid is not flammable, leakage can potentially contaminate or corrode metal components. Given the open space of the trunk, it’s best to add a mat for isolation or store it in a toolbox to minimize contact. For optimal safety, store it in a garage or shaded area where temperatures are stable and risks are lower. If you frequently keep it in the car as a backup, choose high-quality brands to ensure reliability.

[DelNadia]

Storing windshield washer fluid in the trunk poses safety hazards, especially when temperature changes can cause bottle damage and leakage. Chemical substances like methanol evaporation can irritate the respiratory tract and pollute the environment or interior space. I prefer using eco-friendly formula washer fluid and ensure stable placement in the trunk to avoid collisions. Excessive summer heat may soften and deform plastic bottles, while winter freezing carries a high risk of cracking. It's recommended to store it sealed to minimize leakage risks. The trunk isn't an ideal location - using the glove compartment or door pockets is safer. Avoid long storage periods and conduct regular safety checks.