Causeway Chalet

What it means: This code tracks the combined total nitrogen from both nitrate and nitrite. While each has its own MCL (nitrate: 10 mg/L, nitrite: 1 mg/L), the combined sum is also limited to 10 mg/L as nitrogen. The combined measurement applies when both forms are present, particularly in partially treated or mixed sources where nitrification may be incomplete.

Health effects: The combined limit protects against methemoglobinemia — the same risk as nitrate alone and nitrite alone. In infants under 6 months, gut bacteria convert these nitrogen compounds to forms that block oxygen transport in blood ('blue baby syndrome'). Pregnant women and individuals with certain enzyme deficiencies are also at elevated risk.

Limit: 10 mg/L as nitrogen (NO₂-N + NO₃-N combined)

What it means: The 2013 RTCR (effective 2016) replaced the original TCR. It triggers automatic E. coli testing whenever total coliform is found. A single E. coli-positive sample is an acute MCL violation. It also requires systems exceeding 5% total coliform-positive samples to conduct a formal assessment and correct any deficiencies, helping prevent contamination before it escalates.

Health effects: Total coliform bacteria indicate that the disinfection barrier has been breached or fecal contamination is entering the system. E. coli specifically indicates fecal contamination and the possible presence of disease-causing pathogens (norovirus, Salmonella, Shigella, Campylobacter). Illness can be severe in elderly, young children, and immunocompromised individuals.

Limit: Zero E. coli; ≤5% of monthly samples total coliform-positive