# Water Quality Changes in Cement-Lined Water Pipe Networks
## 1 Introduction
The study by [PERSON] [13] presented leaching of metals from cement mortar as a function of pH and duration of the period in which cement was in contact with water. Based on the revealed relationships, it was observed that the smallest amounts of metals leached into the water when it was neutral. [PERSON] et al. [14] observed increased amounts of chromium, arsenic, barium and cadmium leached from the cement coating, recording their concentrations above the limit values for drinking water. Analyses conducted by [PERSON] et al. revealed a correlation between leaching of heavy metals from the Portland cement and temperature, as well as the period of the experiment, using a new, highly sensitive method that allowed to determine very low concentrations of these elements [15]. Use of cement mortar coatings may lead to penetration of aluminium into the water, with the aluminium content depending on the type of cement. After two months of experiments on steel pipes with cement mortar lining, aluminium content was found to increase from 0.005 mg/dm\({}^{3}\) to 0.690 mg/dm\({}^{3}\). This element affects human health and it is particularly dangerous for patients undergoing kidney dialysis [16]. Due to the fact that the leaching of aluminium from Portland cement occurs in low-alkalinity water, [PERSON] et al. [16] recommend that internal coatings made in situ from regular Portland cement should not be used in water with an alkalinity lower than 55 mg/L as CaCO\({}_{3}\) and that factory-made internal cement coatings should not be used in water with alkalinity lower than 25 mg/L as CaCO\({}_{3}\). It is also recommended that the use of high alumina cement lining should be limited in pipelines used for distributing drinking water, due to much higher aluminium content leached from this type of cement into the water, when compared to Portland cement [3; 6]. The discussed topic is not new. However, previous studies focused on the laboratory, mainly static, leaching tests. This paper presents new studies conducted under real dynamic conditions, based on a new 90 m experimental set. The hydraulic conditions in this set reflected the average conditions in the entire network, determined on the basis of field measurements and numerical calculations (using a numerical model devised in EPANET 2.0 software, US EPA, Washington D.C., USA, 2000). In this paper, the composition of cement lining was connected with the changes in the quality of water transmitted via lined pipeline. The occurrence of changes in the water quality was indicated both in short (hourly) and long-term (daily). The available literature offers no exhaustive information on the impact of cement mortar lining of water conduits on the quality of the conveyed water. This is because the interaction between water and cement lining is determined by many factors; a significant role is played by water composition and type of lining but also properties of the contacting water. Also, state-of-the-art laboratory methods vary and quite often fail to reflect real-life conditions found in water supply networks. In light of the above, this paper presents a properly designed study conducted using the experimental setup, with the main purpose of determining the impact of cement coating covering the internal surface of a water conduit made of ductile iron on water quality in terms of changes in its physico-chemical properties.