Rainwater alkalinity, chloride-ion, conductivity, pH and nutrients data from the Frome Piddle; Pang Lambourn and Tern catchments, recorded between 2004 and 2006. Rainwater samples were collected fortnightly at seven sites in these catchments and analysed for Alkalinity pH 4.5, Ammonia, Chloride-ion, Conductivity 20 °C, Nitrate, pH, Phosphorus soluble reactive (SRP), Silicate reactive dissolved (SRD) and Sulphate. The samples were collected as part of the NERC funded Lowland Catchment Research (LOCAR) Programme to provide comparable baseline rainwater chemistry data across the LOCAR catchments.