Extreme care should always be taken when handling acids and bases as hazardous reactions may occur and fumes may be produced. Acids and bases are corrosive and can cause severe skin and eye damage.
Dilute and Flush
Following the usage directions on the container may be the best way to dispose of these chemicals if other disposal options aren’t available. This will often involve diluting the chemical and disposing of it down the drain. This is the least-preferred disposal option, but it may be the only option available in some areas. If your home is connected to a septic tank, give these products to someone who is connected to a municipal sewer system. Even in a diluted form, these chemicals can destroy the bacterial action in your septic system and drain field. Acids and bases should never be disposed of on the ground or in a storm drain or gutter since they can contaminate groundwater, surface water and (potentially) drinking water supplies.
Provide adequate ventilation by opening windows and doors and/or turning on a room fan.
Wear protective clothing such as chemical resistant gloves, eye protection and long sleeves.
Unless the usage direction specify otherwise, carefully pour 1/4 to 1/2 cup of the acid or base into 2-5 gallons of water, taking care not to splash or spill. Always add the chemical to the water and not the water to the chemical. Failure to dilute the concentrate may seriously damage pipes or other parts of your plumbing.
Pour the diluted solution slowly down the sink, flushing with large amounts of water and taking care not to splash.
Continue disposing in 2-5 gallon batches of diluted solution until completely gone. Don't mix products, and wait several hours between disposing of different types of products.
The best time to do this is during the working day when the sewage system is in full use so that this material passes through the municipal sewage system faster.
These procedures are intended for small quantities of acids or bases from a household only.