The solubility of calcium carbonate CaCO3 in water at 25C is quite low, approximately 15 mg/L or 0.015 g/L. This means that only 15 milligrams of calcium carbonate can dissolve in 1 liter of water at this temperature.There are several ways to increase or decrease the solubility of calcium carbonate in water:1. Temperature: Generally, the solubility of most salts increases with temperature. However, the solubility of calcium carbonate decreases with increasing temperature. So, to increase the solubility of CaCO3, you can lower the temperature, and to decrease its solubility, you can raise the temperature.2. pH: The solubility of calcium carbonate is also affected by the pH of the solution. It is more soluble in acidic solutions lower pH because the carbonate ion CO3^2- reacts with the hydrogen ions H+ to form bicarbonate ions HCO3^- . To increase the solubility of CaCO3, you can add an acid e.g., hydrochloric acid, HCl to the solution, which will lower the pH. To decrease the solubility, you can add a base e.g., sodium hydroxide, NaOH to increase the pH.3. Common ion effect: The presence of a common ion in the solution can also affect the solubility of calcium carbonate. According to Le Chatelier's principle, if a common ion is added to a solution, the solubility of the salt will decrease. For example, if you add calcium chloride CaCl2 or sodium carbonate Na2CO3 to the solution, the solubility of CaCO3 will decrease due to the common ion effect.4. Complexation: The solubility of calcium carbonate can be increased by forming soluble complexes with other ions or molecules. For example, adding a chelating agent like ethylenediaminetetraacetic acid EDTA can increase the solubility of CaCO3 by forming a soluble complex with the calcium ions.