The article presents the results of the research on the water samples taken from the Krakow water

distribution system and their pollution by haloacetic acids: monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, trichloroacetic acid, bromochloroacetic acid and dibromoacetic acid. The water samples were

taken from the extremities of the distribution systems (Raba and Bielany) in the city of Krakow. Both analyzed

plants use the chlorination as the water treatment process, however, water for Raba and Bielany comes from

different surface waters and differs in quality and organic matter concentration. These plants also apply different

water treatment processes and their distribution systems have a different size. The objective of this study was

to measure the haloacetic acids levels in these two water distribution systems, asses the correlation between the

total trihalomethanes and the sum of six haloacetic acids, determine if trihalomethanes can be a good indicator

to predict haloacetic acids concentration in water distribution systems.

The paper presents the results of experiments on the influence of the organic matter’s characteristics on the formation potential of water chlorination by-products – representatives of the following groups:

trihalomethanes, haloacetonitriles, haloketones, chloral hydrate and chloropicrin. The products of water fractionation (the hydrophobic and hydrophilic acids, hydrophobic and hydrophilic bases, and hydrophobic and

hydrophilic neutral fractions) were chlorinated with sodium hypochlorite. Its dose was adjusted to obtain a

residual free chlorine concentration between 3 and 5 mg/dm3

after 24 h. After this time, the water chlorination

by-products were analyzed with gas chromatography. The results’ analysis has defined the fractions, which have

the highest potential to form particular groups of volatile organic water chlorination by-products.