Room temperature ionic liquids (RTILs) have engaged much attention in recent years, especially due to their use as environmentally friendly alternatives to typical organic solvents. Their negligible vapor pressures incentivize their use as green solvent alternatives relative to the typical volatile organic solvents. However, it is necessary to consider the entire life cycle of the RTIL; for example, the potential hazardous properties associated with its hydrolysis by-products (tetrafluoroborate hydrolysis) merit consideration. Using ¹⁹F and ¹¹B NMR analyses, we present the observation of hydrolysis behavior of the aliphatic quaternary ammonium-based ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (denoted as [DEME][BF₄]). It has been observed that the hydrolysis of [DEME][BF₄] rapidly proceeds when the water concentration exceeds x › 80 (mol % H₂O).