# Water Quality Changes in Cement-Lined Water Pipe Networks
## 3 Results  
### Analysis of Test Results for Water Feeding the Setup, Considering Its Corrosive Properties  
Based on the obtained results of the physico-chemical analysis (Table 1), it may be found that the setup for the entire period of the experiment was fed with water of variable quality due to employment of different wells in the intake. Changes in carbon dioxide and dry residue concentrations, that is, parameters significant in terms of corrosive properties of the water, are particularly clear. In general, feeding water had a pH approximating neutral (pH ranging from 6.90 to 7.53), very low colour (1 mg/L) and turbidity (from 0.45 to 0.89 NTU, single result of 1.04 NTU), as well as moderate salinity, which is primarily reflected by the values of such indicators, as general hardness (6.8 \(\div\) 8.2 mval/L), alkalinity (5.4 \(\div\) 6.3 mval/L), chloride (17.8 \(\div\) 39.0 mg Cl/L) and sulphate content (60 \(\div\) 86 mg SO\({}_{4}\)/L), as well \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**Unit**} & \multicolumn{5}{c}{**Sample**} & \multicolumn{3}{c}{**Limit Value**} \\  & & **No 1** & **No 2** & **No 3** & **No 4** & **No 5** & **Water [17, 18]** \\ \hline temperature & \({}^{\circ}\)C & 10.5 & 10.8 & 12.4 & 11.0 & 10.2 & - & - \\ colour & mg Pt/L & 1 & 1 & 1 & 1 & 1 & 15 & PN EN ISO 7887:2012 \\ turbidity & NTU & 0.48 & 0.45 & 1.04 & 0.89 & 0.55 & 1 & PN EN ISO 7027:2003 \\ pH & - & 7.06 & 7.18 & 6.90 & 7.53 & 7.11 & 6.5 \(\div\) 9.5 & PN EN ISO 100523:2012 \\ alkalinity & mval/L & 5.9 & 5.7 & 5.4 & 6.3 & 6.2 & - & PN EN ISO 9963-12001 \\ hardness & mval/L & 7.4 & 7.3 & 6.8 & 7.8 & 8.2 & 1.2 \(\div\) 10 & PN ISO 6059:1999 \\ calcium & mg Ca/L & 122 & 119 & 113 & 104 & 122 & - & EDTA Method \\ iron & mg Fe/L & 0.08 & 0.07 & 0.24 & 0.10 & 0.07 & 0.2 & PC Multidirect \\  & & & & & & & & Method 220 \\ manganese & mg Mn/L & 0.018 & 0.015 & 0.021 & nd & nd & 0.05 & HACH Method 8149 \\ chlorides & mg Cl/L & 17.8 & 18.2 & 21.3 & 32.0 & 39.0 & 250 & PN ISO 9297:1994 \\ sulphates & mg SO\({}_{4}\)/L & 72 & 71 & 60 & 86 & 82 & 250 & HACH Method 8051 \\ chemical oxygen & mg O\({}_{2}\)/L & 1.2 & 1.3 & 4.6 & 1.8 & 0.8 & 5 & PN-74/C-04578-03 \\ demand & mg H\({}_{4}\)/L & 0.005 & 0.008 & 0.013 & 0.090 & 0.141 & 0.5 & HACH Method 8038 \\ antimutism & mg O\({}_{3}\)/L & 11.3 & 9.7 & 12.0 & 15.8 & 9.2 & 50 & HACH Method 8039 \\ free CO\({}_{2}\) & mg/L & 9.2 & 9.4 & 50.6 & 50.6 & 35.2 & - & PN -74/ C-04547/01 \\ aggressive CO\({}_{2}\) & mg/L & nd & nd & nd & nd & - & PN -74/ C-04547/03 \\ oxygen & mg O\({}_{2}\)/L & 7.8 & 8.1 & 7.7 & 6.7 & 5.3 & - & Winkler Method \\ dry residue & mg/L & 389 & 358 & 542 & 494 & 521 & - & PN -75/ C-04616/01 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Quality of the water feeding the experimental set-up. as dry residue content (358 \(\div\) 542 mg/L). Iron concentration failed to exceed 0.10 mg/L (single result of 0.24 mg/L was reported), whereas manganese concentration did not exceed 0.021 mg/L. Organic matter burden may be regarded as relatively low due to the values of chemical oxygen demand (0.8 \(\div\) 1.8 mg/L; single value of 4.6 mg/L), ammonium ion (0.005 \(\div\) 0.141 mg/L) and nitrate ion (9.2 \(\div\) 15.8 mg/L) indicators. The analysed water was reported to contain gas admixtures, such as carbon dioxide with concentration ranging from 9.2 to 50.6 mg/L and oxygen (5.3 \(\div\) 8.1 mg/L). When comparing the quality of the feeding water with standards set out for water for human consumption [17; 18], it should be stated that in terms of compliance with these standards, the water quality raised no concerns as regards the analysed physico-chemical indicators. The basic indicators used to approximately identify water impact on the cement coating are the Ryznar Stability Index (RSI) and the Langelier Saturation Index (LSI), as well as an index proposed by American Water Works Association (AWWA) [20].