By Claire Gillespie
Updated Mar 24, 2022

MadamLead/iStock/GettyImages

Hydrochloric acid, commonly called muriatic acid, is a highly corrosive solution of hydrogen chloride. It’s used in manufacturing batteries, fireworks, gelatin, and sugar processing, and it’s also produced naturally in the stomach as gastric acid. Because of its corrosive nature, it must be treated as hazardous waste. Disposal methods differ by state, so check local regulations before proceeding.

TL;DR

Before disposing of hydrochloric acid, verify your state’s rules. Some states permit dilution and flushing, while others require neutralization first. Handle the acid with extreme care to avoid injury and environmental damage.

Diluting Hydrochloric Acid

In jurisdictions that allow dilution, follow these steps:

• Ventilate the area—open windows and doors.
• Wear protective gear: long sleeves, safety goggles, a mask, and rubber or neoprene gloves.
• Carefully pour 1/4 to 1/2 cup of hydrochloric acid into 2–5 gallons of water. Always add acid to water, not the reverse.
• Slowly pour the diluted solution down the sink, flushing with plenty of water to minimize splashes.

Neutralizing Hydrochloric Acid

Where state regulations require neutralization before disposal, use an alkali such as sodium bicarbonate (baking soda):

• In a well‑ventilated area far from children, pets, heat, and metal surfaces, don’t forget protective clothing.
• Mix 1 lb of baking soda with plenty of water to form a base solution.
• Slowly add the hydrochloric acid. The mixture will fizz—continue adding baking soda until fizzing ceases.
• Once neutralized, the solution can be flushed down the sink with ample water.

What Not to Do

Never dispose of hydrochloric acid in the following ways:

• Don’t flush it into a septic system—even if diluted—as it can kill the bacteria essential for waste breakdown.
• Avoid pouring it onto the ground, into storm drains, or gutters to prevent groundwater, surface water, and drinking water contamination.
• Do not discard it in household trash; leaks can cause serious injury.

Get Local Guidance

If you’re unsure how to comply with local rules, contact your municipal waste authority. Many towns offer professional disposal services for a fee, and local pool companies or waste‑management plants may accept hazardous acids for recycling or safe disposal.

Key Safety Reminders

• Always read the label and any accompanying safety data sheet (SDS).
• Keep the acid container sealed and upright when not in use.
• Store acid separately from bases, oxidizers, and combustible materials.
• Use a secondary container for transport to avoid spills.