Common household substances that are acidic include coffee, battery acid, vinegar and lemon juice, while common household substances that are basic include drain cleaner, bleach, soap, ammonia, milk of magnesia and baking soda. An acid is a substance that has a pH value of less than seven, while a base is a substance that has a pH value of greater than seven.
Other household substances that are acidic include soda (carbonic acid), fruit (ascorbic acid), citrus (citric acid), tea, wine (tannic acid) and grapes (tartaric acid). Both fresh milk and sour milk contain lactic acid, which gives the substances a low pH value. Likewise, eggs, borax and distilled water are bases with pH values over seven. Substances that are soluble bases are referred to as alkali.
According to the BBC, many vinegars contain ethanoic or acetic acid. Common household substances that are basic contain sodium hydroxide and copper oxide. Cleaners contain basic substances so that they can react with oil and fat to clean items. Toothpaste and antacid tablets contain weak bases in their ingredients.
The pH levels of household items can be tested with a litmus indicator. Acidic substances do not change red litmus paper, while a basic substance turns the litmus paper blue.