Influence of Household Water Filters on Bacteria Growth and Trace Metals in Tap Water of Doha, Qatar

Abstract

Deteriorating water quality from aging infrastructure, growing threat of pollution from industrialization and urbanization, and increasing awareness about waterborne diseases are among the factors driving the surge in worldwide use of point-of-entry (POE) and point-of-use (POU) filters. Any adverse influence of such consumer point-of-use systems on quality of water at the tap remains poorly understood, however. We determined the chemical and microbiological changes in municipal water from the point of entry into the household plumbing system until it leaves from the tap in houses equipped with filters. We show that POE/POU devices can induce significant deterioration of the quality of tap water by functioning as traps and reservoirs for sludge, scale, rust, algae or slime deposits which promote microbial growth and biofilm formation in the household water distribution system. With changes in water pressure and physical or chemical disturbance of the plumbing system, the microorganisms and contaminants may be flushed into the tap water. Such changes in quality of household water carry a potential health risk which calls for some introspection in widespread deployment of POE/POU filters in water distribution systems.

Figure 1

Locations of housing units in Doha that participated in the study. (Created using ArcGIS -a GIS software).

Figure 2

Typical point-of-entry filtering system (Lavender Village residence), Doha.

Figure 3

(A) Filter membrane showing heavy accumulation of residues; the beaker shows the brownish slurry within the POU unit. (B) Comparison of new filter (left) and one that had been installed for four months (right). The cartridge taken out of the filter is shown separately on the right.

Figure 4

HPC counts in city (service line) water, household water (pre-POE water) and tap water (post-POU filter). (Created using Minitab® version 17.1.0 (2013), Minitab Inc.).

Figure 5

Community structure of microorganisms in different water samples. A = service line water; B = household water; C = tap water; D = water within the filter; POUs = residues on filter membranes. Y-axis shows the relative proportion of each group of microorganisms in the sample.