Legionella & Hot Water
Monitoring
Continuous, in-pipe monitoring of five critical parameters — free chlorine, pH, ORP, conductivity, and temperature — for building water systems. ASHRAE 188 requires a water management program with documented control limits. CDC treats residual, temperature, and pH as WMP control limits, not a named analyzer. In-pipe data can support those limits without grab samples or a waste stream.
Quick Answer
How do buildings monitor for Legionella control?
See the proof: certifications, patents & field results.
The Regulatory Landscape
ASHRAE Standard 188
Establishes minimum legionellosis risk-management requirements for building water systems, including a water management program. It does not name an analyzer or require 24-hour online residual, pH, ORP, or conductivity.
View Resource open_in_newCDC Toolkit
Practical guidance for developing water management programs, emphasizing control limits for disinfectant levels and temperature.
View Resource open_in_newP.L. 2024, c.66 (S2188)
Public community water systems over 100 connections must hold 0.3 mg/L free chlorine or 1.0 mg/L monochloramine in the distribution system. Listed buildings must develop an ASHRAE 188 water management program. Those residual numbers are not a hot-water-line analyzer mandate.
The Problem with Existing Solutions
Traditional reagent-based systems are ill-suited for the rigorous demands of modern facility management.
Massive Environmental Waste
Standard analyzers produce over 70,000 gallons of chemical-laden waste stream annually per unit.
The "Gap" Problem
Manual grab samples miss 99.9% of operational hours, failing to detect transient biofilm releases or disinfectant drops.
The MP-HOT Advantage
- boltDirect In-Pipe AnalysisNo sample lines or reagents required.
- thermostatHigh-Temp Tolerance (Up to 60°C)Engineered specifically for hot water return loops.
- science5 Parameters, 1 SensorFree chlorine, pH, ORP, conductivity, and temperature.
- eco$1,440/Year Total Savings$490 water + $950 energy recovered from waste-stream elimination.
- cleaning_servicesSelf-Cleaning SensiCLENEAutomated mechanical electrode cleaning prevents scaling.
Integrated with LAMPS Water Management Software
Halogen is an authorized LAMPS sensor data integration partner. MP-HOT sensor data feeds directly into HC Info's LAMPS platform for automated compliance reporting, trend analysis, and real-time Legionella risk management — giving facility managers a single pane of glass for their entire water management program.
Explore LAMPS at HC Info open_in_newWhere to Install
Hot Water Return Loop
Primary verification point for system-wide disinfectant residuals.
Point of Use
Critical monitoring for high-risk areas like showers and sinks.
Hot Water Heater Outlet
Monitors temperature and chemical efficacy immediately post-heating.
Frequently Asked Questions
What is ASHRAE Standard 188?
It requires a water management program (building survey, control measures, confirmation). Control limits for disinfectant residual, temperature, and pH are set in the WMP. The standard does not require continuous monitoring of residual, pH, ORP, conductivity, and temperature, and it does not name an analyzer.
Does continuous chlorine monitoring satisfy ASHRAE 188 requirements?
No. ASHRAE 188 is satisfied by a documented water management program, not by a specific instrument. Continuous in-pipe residual and temperature records can support the WMP's control limits and catch drops that weekly grab samples miss. They do not, by themselves, satisfy 188.
What parameters does the MP-HOT sensor measure?
The Halogen MP-HOT sensor measures five parameters in a single in-pipe probe: free chlorine, pH, ORP, conductivity, and temperature. It operates in water temperatures up to 60°C (140°F), making it specifically designed for hot water return loops.
Why are manual grab samples insufficient for Legionella compliance?
Manual grab samples are typically collected once per week, meaning they miss 99.9% of operational hours. Disinfectant residual can drop and recover between sampling events, leaving biofilm growth undetected. Continuous monitoring provides real-time data every two minutes or less.
What facilities must comply with ASHRAE 188?
ASHRAE 188 applies to human-occupied commercial, institutional, multi-unit residential, and industrial buildings, not single-family. A WMP duty depends on the standard's survey and on any adopting statute (NJ c.66 lists specific types).
How do I monitor chlorine for Legionella water management?
Use the Halogen MP-HOT to continuously monitor free chlorine (or chloramine), pH, conductivity, and temperature in recirculating hot-water loops up to 140°F. That in-pipe record can document residual and temperature against the control limits in an ASHRAE 188 / CDC water management program, instead of relying on weekly grab samples.
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