Washington – September 08, 2026 -- Independent testing commissioned by the Alliance to Prevent Legionnaires' Disease (APLD) found Legionella bacteria in 17 percent of 109 water samples collected from sinks, showers, hose bibs and other fixtures across the Upper East Side outbreak zone, results the group says expose gaps in New York City's current prevention strategy.
Testing detected live, culturable Legionella pneumophila serogroup 1 across all three sampled zip codes
The independent consultant collected samples in mid-July across zip codes 10128, 10028 and 10075, the area the City identified as the outbreak zone. Legionella was found in 19 buildings, including 10 exterior hose bibs, seven sinks, one shower and a decorative fountain. Positive samples showed Legionella concentrations ranging from less than 1 to 390 CFU/mL, with Legionella pneumophila serogroup 1 confirmed in all three zip codes.
Chlorine residuals averaged 0.12 mg/L, well below EPA-recommended levels
Samples showed average chlorine treatment residuals of 0.12 mg/L, less than a quarter of the 0.5 mg/L level recommended by an EPA workgroup. The results were provided to the New York City Department of Health.
City testing during the outbreak covered 183 cooling towers but not building plumbing systems
APLD board member Bob Bowcock, a licensed water treatment operator and founder of Integrated Resource Management, said the City tested 183 cooling towers but has not publicly identified comparable testing of distribution system water or building fixtures before declaring water safe for use. "You cannot rule out a point of exposure you never tested," Bowcock said, adding that cooling towers represent only one segment of a system running from source to tap.
APLD board members testified before the NYC Council on September 2
Board members questioned the City's narrow focus on cooling towers during a September 2 NYC Council hearing on Legionnaires' prevention policy.
CDC data show 96 percent of Legionnaires' cases are sporadic, not outbreak-linked
New York carries one of the country's highest Legionnaires' disease burdens. Bill McQuade, APLD board member and immediate past-President of ASHRAE, said finding Legionella in a three-day sample of ordinary fixtures should prompt a fuller investigation of the water distribution system, arguing no responsible prevention strategy should focus on a single risk factor.
New Jersey and Illinois have adopted source-to-tap regulatory models APLD wants replicated
APLD is backing state legislation modeled on a 2024 New Jersey law and Illinois water quality regulations in effect since 2019, which include minimum disinfectant-residual standards for public water systems and building water management plans consistent with ASHRAE Standard 188-2021.