Proper disposal of muriatic acid is carried out by mixing it with a 10 percent sodium carbonate solution to neutralize it. However, muriatic acid is a hazardous substance, so it's a good idea to check with your local hazardous-waste disposal department for specific disposal information. When in doubt, contact it for help.
In most locations, after muriatic acid has been neutralized, it can be disposed of into the sewer. Before disposing of neutralized muriatic acid, it's recommended to check the pH with a pH strip to make sure the pH is near seven.
Disposal of muriatic acid is strongly recommended if storage is impractical. Although laboratory-grade sodium carbonate is preferred for neutralization, it's possible to use food-grade baking soda.
Muriatic acid is a hazardous substance that must be handled with care. Recommendations for its handling include wearing personal protective equipment such as nitrile gloves, 100-percent-cotton long-sleeved shirts and pants, and safety glasses or goggles. If muriatic acid is being stored, it must be stored upright in a closed container and checked regularly for leaks.
Muriatic acid should only be neutralized in a fume hood or open area, so the fumes given off by the acid are dispersed or extracted. Using a fume hood is preferable because even the vapor is corrosive and hazardous.