The purity of Brecon Carreg Natural Mineral Water originates from its natural source. The special geological features in this area means that the main water bearing aquifers, which are millstone and sandstone, overlie a hard and insoluble limestone band. As the water has gradually percolated into the limestone below, it then flows rapidly underground. Because the water has been held mainly in the grit and sandstone the contact time with the limestone is small. Therefore, the minerals and salt content remain low. For 15 years it percolates through limestone strata, being naturally purified and gaining its unique taste before being bottled at source in the village of Trap, near Llandeilo in Carmarthenshire.