In this work, we present the water-based synthesis of the Zr-fumarate MOF (Zr-fum MOF) by applying a monocarboxylic acid as modulator. The original synthesis of Zr-fum MOF was performed in a DMF-based batch at 120 °C. The product showed exceptional stability against aqueous solutions. Thus, a water-based synthesis seemed to be promising. Indeed, by adding various amounts of formic acid, acetic acid or propionic acid as modulator, respectively, highly crystalline Zr-fum MOF can be obtained from water at 120 °C. The investigation of the influence of modulating molecules with different alkyl chain lengths showed that the particle size decreases when monocarboxylic acids with longer alkyl chains are used, e.g. acetic acid and propionic acid in comparison to formic acid. For the formation of the Zr-fum MOF synthesised with formic acid as modulator, the thermogravimetric and sorption behaviour as well as the stability against various solvents and pH values is discussed in detail. Furthermore, the Zr-fum MOF can also be obtained under very benign reaction conditions at room temperature from water, making this material interesting for various applications, for example as a biomaterial.