<p>Somatic coliphages are recognized reliable indicators of faecal contamination in water. Their routine monitoring relies on time-consuming, labour-demanding culture-based methods, which are limited to detecting total somatic coliphages. Here, we developed and validated a novel family-specific quantitative PCR (qPCR) assay targeting four major families of somatic coliphages—<i>Myoviridae</i>, <i>Podoviridae</i>, <i>Siphoviridae</i>, and <i>Microviridae</i>—to enhance sensitivity, specificity, and throughput. The assays were designed using in silico primer screening against reference genomes. The qPCR assay was specific to the phage families (100% assay specificity within the tested prototypes) and had a LOD and LOQ of 10.4 copies/µl, 2.7 copies/µl, 26.5 copies/µl, and 3.3 copies/µl for <i>Myoviridae, Microviridae, Podoviridae</i> and <i>Siphoviridae</i>, respectively. Efficiencies between 90 and 110% were achieved. Coefficients of determination (<i>R</i>²) were 0.993–0.996. Comparison of ISO (culture-based method) and qPCR methods revealed significant correlations (<i>p</i> &lt; 0.05), showing that the methods are comparable. The qPCR method was tested on a range of environmental waters to demonstrate wide application of the assay. This showed season and source-specific patterns in phage family distribution, with <i>Podoviridae</i> and <i>Siphoviridae</i> significantly enriched in winter-collected farm water samples, and <i>Myoviridae</i> dominating in farm summer samples, and a more even phage-family relative abundance in wastewater with no significant differences. We suggest that this qPCR assay could be used as a screening tool to complement standard protocols for regulatory monitoring, ensuring drinking water safety. It is also a valuable research tool for investigating the environmental ecology of somatic coliphages and understanding sources of faecal pollution.</p><p></p>