# Water Quality Changes in Cement-Lined Water Pipe Networks
## 2 Materials and Methods  
The study was conducted in an experimental setup composed of the main pumping station supplying a water supply network in a selected city (Figure 1). Water was abstracted from intakes located in underground Cretaceous formations using 8 wells, from 55 to 70 metres deep. Abstracted water met the requirements for drinking water set out in WHO [17] and Polish National Standards [18] and except for periodic chlorination, it requires no treatment.  
The experimental setup was made of ductile iron pipes with a total length of 80 m and an internal diameter of 65 mm. The working volume of the experimental setup was 250 dm\({}^{3}\).  
The study was composed of three testing series:  
Series I--long-term (multiple day) stagnation of water in the setup. Duration of the series until stabilisation of water quality in the setup. Water samples were collected once a week.  
Series II--short-term (few hour) stagnation of water in the setup. Water samples were collected from the setup after 0, 1, 2, 4, 8, 16 and 32 h.  
Series III--water flow through the installation at the velocity of 0.1 m/s. Water samples for the analyses were collected during the supply and drainage of the water from the setup, considering retention times of the water in the pipeline.  
Figure 1: View (**left**) and schedule (**right**) of measuring stand; 1—a set of pump in pumping station II-nd degree, 2—valve \(\phi\)50, 3—pipe, galvanized steel \(\phi\) 50 mm, L = 1.2 m, 4—splitter, a set of galvanized fitting \(\phi\)50, 5—socket for sampling, \(\phi\)15, 6—ball valve \(\phi\) 50 mm, 7—valve \(\phi\)65, 8—part of the ductile iron pipe for the microbiological testing \(\phi\)65, 9—ductile iron pipes \(\phi\)65 lined with cement mortar, L = 80 m.  
The experimental setup was chlorinated and washed before every series. Before each series of measurements, a water sample was collected in order to determine the initial conditions. Physico-chemical analyses of water samples determining changes in its quality were conducted in accordance with applicable analytical standard methods. The standards according to which the measurements of particular water quality parameters were conducted are presented in Table 1. The analysis of every water quality parameter in each sample was performed in triplicate and the average of the results are presented in the tables. Trace element content in the water and in the cement coating was measured using the JY238 Ultrace Inductively Coupled Plasma--Optical Emission Spectrometer (ICP-OES) (Jobin Yvon-Horriba, Montpellier, France) [19]. The calibration solutions were prepared using CentiPUR (r) VIII multi-element calibration solution (Merck group, Darmstadt, Germany, 2013). In order to conduct a more accurate quantitative determination of elements, the investigations were carried out in two phases. In the initial phase, a fast semi-quantitative analytic methodology was employed. This phase, as well as the previous results of studies on cement lining, enabled the determination of the elements that had to be subjected to further quantitative indication with a more accurate method (second phase). In that phase, determination was carried out by means of inductively coupled plasma mass spectrometer (ICP-MS, 7700x, Agilent, Polo Alto, USA). Similar to the initial phase, the quantitative determinations were performed using calibration curves and the same pattern. The scope of analytical control of water samples is presented in the tables containing results of relevant analyses.