Liquid scintillation spectrometry is used widely for determining 222Rn in natural waters; however, the benefits of α/β separation have not been fully explored. The extractants toluene and Ultima Gold F were compared, and both performed well for a range of extreme waters. A robust method for calibrating extraction and counting efficiencies has been developed. Detection limits are 20 mBq l−1 (toluene) and 16 mBq l−1 (UGF) for a 60 min count and 600-ml sample, halving the required sample volume.