Sequence analysis methods for covid-19 evidence used in molecular biology, such as NGS or RT-PCR, only deliver reliable results with ultra pure water system Type I. Highest water quality should be used for highly sensitive applications, including preparation of reagents and buffers for sequencing. 

If the laboratory water contained impurities, including ions (e.g. magnesium, iron), organic substances (e.g. humic acids), bacteria and their decomposition products (e.g. nucleases), particles or gases, small numbers could have direct impact on DNA or enzymatic reaction.