NGS or Next-Generation Sequencing, introduced since 2000, is a fast technique that determines the order of the nucleotides (or bases) adenine, guanine, cytosine and thymine in DNA or RNA. Unlike first-generation sequencing, NGS can sequence the entire genome of an organism at once. The DNA is first fragmented into small pieces. The nucleotide sequence of these pieces is then determined. The entire genome can be reconstructed via overlapping sequences. This method is mainly used for instruments of the Illumina platform (1). New DNA sequencing techniques are still under development. For example, it is currently possible to sequence much longer stretches of DNA using a technique developed by Oxford Nanopore (2).
Since 2015, NGS has been used for research in the drinking water world. NGS can generate a nearly complete picture of the microbial population composition in water. As a result, NGS is valuable for determining the water quality, and for understanding the processes that occur during purification.