Gels/Balms made with Sapogel Q normally have a low water content. Indeed, the maximum water phase we recommend in a balm is 4%. Additionally, Sapogel Q contains a high level of glycerine which protects it from contamination with micro-organisms by lowering the water activity. As such they normally don't need preservation, but potassium sorbate and sodium benzoate are a compatible combination if a preservative is a requirement.