Water quality problems associated with intermittent water supply

Abstract

A controlled study was conducted in Lebanon over a period of 12 months to determine bacterial regrowth in a small network supplying the Beirut suburb of Naccache that had a population of about 3,000. The residential area, which is fed by gravity, is supplied twice a week with chlorinated water from two artesian wells of a confined aquifer. A significant correlation was detected between the turbidity and the levels of heterotrophic plate count bacteria (HPC) in the samples from the distribution network as well as from the artesian wells. However, a negative significant correlation was found between the temperature and the HPC count in the samples collected from the source. A statistically significant increase in counts, possibly due to regrowth, was repeatedly established between two sampling points lying on a straight distribution line but 1 km apart. Faecal coliforms were detected in the source water but none in the network except during a pipe breakage incident with confirmed Escherichia coli reaching 40 CFU/100 mL. However, coliforms such as Citrobacter freundii, Enterobacter agglomerans, E. cloacae and E. skazakii were repeatedly isolated from the network, mainly due to inadequate chlorination. A second controlled study was conducted to determine the effect of storage on the microbial quality of household storage tanks (500 L), which were of two main types - galvanized cast iron and black polyethylene. The mean bacterial count increased significantly after 7 d storage in both tank types. A significant difference was found in the mean HPC/mL between the winter and the summer. Highest counts were found April-June although the maximum temperature was reported later in the summer. A positive correlation was established between the HPC/mL and pH, temperature and storage time.

Intermittent Domestic Water Supply: A Critical Review and Analysis of Causal-Consequential Pathways

“…Private storage is a consequences of residents' private investment in infrastructure [6,33]. Nevertheless, private storage causes poor water quality [46,55,110], pressure surges in the system [13,48], and consumer overdraw [2,23,35,50,76,114]. Additionally, some authors found that private storage wastes water [23,35,70,81,128], while others found that in systems with more reliable supply, water storage did not result in more water use [18,47].…”

Degradation of EPDM seal used for water supplying system

“…degradation of the EPDM, itself, and reaction of carbon black. The degradation of the EPDM may be associated with oxidation, chlorination, crosslinking and so forth, since the city water contains air, and it is mixed with chlorine dioxide, sodium hypochlorite and calcium hypochlorite as a disinfectant to prevent proliferations of bacteria and virus [6,7]. Furthermore, the city water is frequently heated with a boiler to keep warm, so that the degradation of the EPDM seal may be accelerated at the elevated temperature.…”

Effect of Women’s Perceptions and Household Practices on Children’s Waterborne Illness in a Low Income Community

“…Studies have established that unsafe water is directly associated with pollution sources, inadequate or lack of treatment, poor water distribution systems, and illegal and nonengineered water connections (Mintz et al 1995;Ahmed et al 1998;Semenza et al 1998;Sobsey 2002;Clasen and Bastable 2003;Sobsey et al 2003;Tokajian and Hashwa 2003). Further, water at the household level may be exposed to sources of contamination due to unsanitary practices in relation to its collection, storage, and handling (Han et al 1989;Jensen et al 2002;Clasen and Bastable 2003;Clasen and Mintz 2004;Wright et al 2004).…”