Effects of installing point-of-use filters intended for lead removal on drinking water quality

Defects in the aging drinking water distribution system can lead to elevated concentrations of toxic metals and harmful microorganisms that pose a risk to human health. Premise plumbing systems can be sites of elevated lead concentrations from lead service lines and are favorable environments for biofilm-forming opportunistic pathogens. To comply with state law requiring no more than 5 parts per billion (ppb) of lead in school drinking water, school administrators installed point-of-use (POU) filters made of activated carbon and ion exchange media in classroom sinks. Before and after common stagnation periods at the school (e.g., overnight, over-the-weekend), water samples were collected from a spigot where water enters the school and from sinks with and without POU filters. Lead, residual chlorine, particles (0.1-50 µm), bacteria, temperature, pH, and total organic carbon were measured. Lead concentrations in all unfiltered samples were below 2.25 ppb, but post-stagnation, over half of filtered samples exceeded 5 ppb. The filters effectively removed free chlorine (99% reduction), and residual chlorine decayed with stagnation. There were higher concentrations of particles and bacteria in filtered samples than in unfiltered samples, especially post-stagnation. Neither of the opportunistic pathogens tested for (Legionella pneumophila and Mycobacterium tuberculosis) were detected. Temperature increased with stagnation, pH decreased with filtration, and total organic carbon was steady across all sample conditions. Installing new filters did not significantly change the filters’ effects on lead concentrations, free chlorine removal, or particle counts. This study revealed that the POU filters in this school did not remove lead after a stagnation period. Filters removed residual chlorine throughout their one-year lifetimes and trapped particles and bacteria which were then released after stagnation. A 5-minute flush of filtered taps reduced lead concentrations, particles, and bacteria.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Environ Engr in Civil Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2020

Author dc:creator

• Clark, Gemma Giovanna

Contributors dc:contributor

• Nguyen, Thanh H
• Liu, Wen-Tso

• Drinking water
• point-of-use filtration
• lead
• residual chlorine
• bacteria

Statement dc:rights

• Copyright 2020 Gemma Clark

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/108628

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/108628