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Four buildings and a flush: Lessons from degraded water quality and recommendations on building water management

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Overview

This field study documented water quality degradation at four Indiana institutional buildings during the COVID-19 pandemic low-occupancy period (March to July 2020). Water use fell by 40 to 75 percent in smaller buildings during peak shutdown; large buildings with hundreds of fixtures required coordinated flushing programs that were largely ineffective without systematic planning. Lead, copper, and manganese all exceeded drinking water limits at some fixtures during the stagnation period. The study found that flushing without as-built drawings and a fixture-specific plan could not reliably restore water quality in complex institutional plumbing.

Key numbers

Maximum concentrations observed across all four buildings (first-draw cold water, total metals by ICP-MS):

  • Lead: 45.4 µg/L (45.4 ppb) — exceeded drinking water limits
  • Copper: 2.7 mg/L — exceeded drinking water limits
  • Manganese: 1.9 mg/L — exceeded drinking water limits

Distribution system water entering the buildings: total chlorine 0.78 to 1.0 mg/L as Cl2; total phosphate approximately 1.0 to 1.2 mg/L as P (proprietary ortho-polyphosphate inhibitor).

Flushing outcomes: 5-minute flushing restored detectable residual chlorine in 3 of 4 buildings. In the largest, oldest building (Building A, constructed 1952, floor area over 19,000 m2), no detectable residual chlorine was observed even after 125 minutes of flushing at the fixture nearest to the point of entry.

Stagnation context: larger and older buildings showed greater ranges of heavy metal concentrations than smaller and newer ones. Corrosion scales, copper, and manganese were detected along with lead in stagnant water, consistent with simultaneous multi-metal mobilization during low-flow periods.

Methods (brief)

First-draw cold water samples (125 mL per sample) from kitchen faucets and drinking fountains at approximately 6 to 25 percent of fixtures per building. Total metals by ICP-MS (SM 3125). Residual chlorine by SenSafe test strips (MDL 0.05 mg/L as Cl2). Building descriptions: ages 1952, 2003, 2007, 2017; sizes 1,440 m2 to 19,100 m2.

Evidence fitness

Supports: documenting lead and co-metal concentrations at institutional building fixtures during prolonged low-occupancy stagnation; demonstrating that flushing without systematic planning fails in complex buildings; establishing that corrosion inhibitor delivery in the distribution system does not guarantee protection at remote or dead-end fixtures during stagnation.

Does not support: quantifying baseline (non-stagnation) lead levels in these or comparable buildings; generalizing stagnation outcomes to residential plumbing; applying these concentrations to risk estimates for occupied buildings under normal use patterns.

Limitations

Sampling covered only one stagnation episode; before-and-after measurements without pre-pandemic baseline for comparison at these specific buildings. Sampling fraction per building (6 to 25 percent of fixtures) may not capture the worst-case fixtures. The COVID-19 low-occupancy scenario is atypical; comparable low-use periods (summer school closures, holiday shutdowns) are common but rarely studied at this intensity. The study used a single public water system source; different source water chemistry and corrosion control programs would produce different outcomes.

Update history

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