COMMERCIAL BUILDING WATER QUALITY: DETECTING CHEMICAL AND MICROBIAL CHANGES, THEIR CAUSES, AND EVALUATING REMEDIAL ACTIONS
In the U.S, more than 5.6 million commercial buildings are in operation and some include offices, schools, and childcare centers. These large buildings have complex indoor plumbing and often drinking water chemical and microbiological safety hazards can go undocumented. Generally, the larger the building’s square footage, the greater number of building occupants potentially exposed to the drinking water and greater amount and complexity of indoor cold and hot water piping and appurtenances. Because commercial buildings routinely undergo periods of low to no water use (e.g., holidays, weekends) cold and hot water can stagnate in the plumbing. This stagnation can allow for chemical and biological drinking water quality safety to deteriorate. This thesis work was designed to examine water safety challenges in school, childcare center, and office buildings to address existing knowledge-gaps.
The study described in Chapter 1 was conducted to better understand the risks of elevated copper levels at U.S. schools and childcare centers. Study goals were to: (1) understand occurrences of copper in school and childcare center drinking water systems, (2) review acute and chronic health impacts associated with the ingestion of copper contaminated water, and (3) examine the effectiveness of remedial actions to address copper in drinking water. Of the more than 130,000 schools and 856,000 childcare centers in the U.S., only about 1.7% of all those facilities had copper drinking water testing data recorded in a federal Safe Drinking Water database since the database was created in 1992. Of these facilities that were designated public water systems, about 13% (2,332) had reported a copper drinking water exceedance. Over a period of 30 years, very few studies have been conducted to document copper levels in schools and childcare centers. Available studies reported widely different sampling protocols and remedial actions. Flushing copper contaminated water from plumbing was the most evaluated remedial action, but flushing sometimes needed to be repeated indefinitely because copper exceeded safe limits within hours after flushing stopped. In-building water treatment with ion exchange systems and orthophosphate corrosion inhibitor addition have been used. At present, there is limited data from testing for copper in schools and childcare centers as well as studies to aid building managers in identifying and remediating copper occurrences.
The study described in Chapter 2 was designed to better understand chemical and microbiological quality in a green office building due to weekend stagnation events (~60 hours per event). Specific goals were (1) to investigate characterize disinfectant, pH, as well as heavy metal and microbial contaminant levels at the building point-of-entry and fixtures throughout the building, (2) understand how water quality varied spatially and by fixture use frequency, and (3) investigate the effectiveness of remedial actions on removing the water quality problems identified. As-built plumbing drawings were used to create a sampling plan and flushing plan. The total chlorine concentration decreased during stagnation (p < 0.05) and was highest at the building entry point (max 0.8 mg/L), and lower throughout the building (max 0.28 mg/L). Total cell counts were greater on Mondays compared to Fridays (p < 0.05). Legionella spp. was highest at the fixture with zero water use recorded during the study. Copper and lead levels throughout the building increase over the weekend (p < 0.05). Copper exceeded the U.S. federal health-based drinking water limit (1.3 mg/L) at 4 of the 12 tested locations. These locations all branched off the same riser. Manual fixture flushing temporarily reduced copper levels, but copper rebounded quickly prompting the need to flush fixtures every 19 hours. Results showed that drinking water testing should be required for building water systems before occupancy permits are issued, and after an extended stagnation period to understand worst case conditions. Testing should include disinfectant level, copper, lead, and legionella.
This thesis research found that a general lack of water testing data for existing office, school, and childcare center buildings inhibited a wider understanding of water safety risks. It is recommended that building officials adopt water testing as a requirement for building occupancy certificates. Testing should also be conducted periodically during the life of the buildings especially after unusually long stagnation periods (e.g., shutdowns or holiday breaks), and in buildings where children or other sensitive populations (e.g., elderly or people with underlying conditions) are occupants. Testing should include disinfectant level, copper, lead, and legionella at the point of entry and multiple locations throughout the building, depending on fixture use and building occupants. Without water testing, occupants may continue to be exposed to water that does not meet federal safe drinking water limits and go undetected. If contamination is found, building managers should review the flushing plan and potentially consider point of use water treatment to address short- and long-term water safety problems.
Frederick N. Andrews Fellowship
- Master of Science
- Civil Engineering
- West Lafayette