Comparison of river and drinking water quality of infiltration intakes based on statistical data of permanganate oxidisability

Comparison of river water and drinking water quality by assessment of permanganate oxidisability at infiltration water intakes. The initial data used were the average monthly values of permanganate oxidisability for the entire observation period and for a model year, reflecting the changes in the indicator in the annual cycle. Time series analysis, correlation analysis and cross‐correlation function were applied. Seasonal changes in the indicator were revealed: the contribution of the seasonal component being 55–59 % for river water and 10–30 % for drinking water. The permanganate oxidisability in the river was 84–87 % higher. A time lag between the maximum oxidisability values was detected: in the river – in May, in drinking water – in June and July. Crosscorrelation analysis showed that the lag was one month. Accounting for the shift in the maximum permanganate oxidisability values strengthened the correlation from "noticeable" to "high" and "very high". It was established that at infiltration water intakes, the increase in permanganate oxidisability to its maximum values in drinking water lags by 1 month compared to river water. This corresponds to the travel time of easily oxidised organic and inorganic compounds that are revealed in permanganate oxidisability of river water.