Is ASHRAE 188 required for apartment buildings?

ASHRAE 188 applies to buildings with centralized hot water systems, cooling towers, or decorative fountains — which includes many multifamily apartment buildings. Even where not legally mandated, maintaining a Water Management Plan (WMP) significantly reduces Legionella liability exposure for property owners and managers.

What is a Water Management Plan?

A Water Management Plan (WMP) is a documented program required by ASHRAE Standard 188 to prevent Legionella growth in building water systems. It identifies hazards, establishes control measures, and defines monitoring protocols for your facility's water systems.

Who needs a Legionella risk assessment?

Any building with a centralized hot water system, cooling tower, decorative water feature, or occupants at heightened risk (elderly, immunocompromised) should have a Legionella risk assessment. This includes hospitals, hotels, apartment buildings, schools, and office buildings.

What is ASSE 12080 certification?

ASSE 12080 is an American Society of Sanitary Engineering standard that establishes competency requirements for individuals managing building water safety programs. It is widely referenced alongside ASHRAE 188 as the standard for Water Management Team qualification.

Legionella Testing: A Step-by-Step Guide for Facility Managers | Legionella Compliance

A cornerstone of any ASHRAE 188 compliant Water Management Program (WMP) is the concept of "Validation"—proving that your control measures are actually preventing the growth of Legionella bacteria. The most definitive way to validate your program is through routine clinical water testing.

However, environmental Legionella testing is highly sensitive to human error. If a maintenance worker improperly collects a sample, it can yield false negatives, giving building owners a dangerous illusion of safety.

Here is the step-by-step, no-nonsense guide to conducting valid Legionella water sampling in a commercial building.

Step 1: Partner with a CDC Elite Certified Laboratory

Before you draw a single drop of water, you must secure a testing partner. Do not send samples to a standard local water lab that specializes in lead or E. coli. Legionella is a notoriously difficult organism to culture.

You must exclusively use a laboratory that has passed the CDC ELITE (Environmental Legionella Isolation Techniques Evaluation) program. These labs have demonstrated the specific microbiological proficiency required to isolate Legionella species from complex environmental water matrices. Your ELITE lab will overnight you the specialized sterile bottles (typically containing sodium thiosulfate to neutralize any residual chlorine) required for the draw.

Step 2: Formulate a Strategic Sampling Plan

Do not test random faucets. Your sampling plan must be strategic and based on the hazard analysis mapped out in your WMP.

According to CDC recommendations, a comprehensive sampling event should include:

The Incoming Water Main: To establish the baseline condition of the municipal water entering your building.
The Heater/Boiler: To verify temperatures directly at the source.
Near Points: Fixtures physically close to the water heater.
Far Points (Terminal Ends): The fixtures furthest away from the mechanical room, where water takes the longest to arrive and disinfectant is most likely to be depleted.
High-Risk Aerosol Generators: Cooling towers, decorative fountains, and hot tubs.

Step 3: The Collection Procedure (Potable Water)

When testing a sink or showerhead, the goal is to capture the water exactly as a building occupant would experience it.

Do NOT Flush First: The sample must be a "first-draw" sample. If you turn on the faucet and let it run before filling the bottle, you are flushing away the biofilm in the fixture and testing the water deep in the pipes, yielding an artificially clean result.
Remove Aerators (Optional but Recommended): Document whether you removed the aerator or showerhead. Testing with the aerator on tests the specific fixture's risk; testing with it off tests the systemic pipe risk.
Fill the Bottle: Open the cold or hot tap and immediately fill the sterile 250mL or 1L bottle. Cap it tightly.
Take Concurrent Readings: Immediately after capturing the sample, you must measure the water's temperature, pH, and Free Residual Chlorine. A Legionella test result is useless for root-cause analysis if you don't know the chemical state of the water at the exact moment of the draw.

Step 4: Storage and Transportation

Legionella bacteria will die if exposed to extreme heat or cold, rendering your sample invalid.

Do not freeze the samples.
Store the sealed bottles in an insulated cooler at room temperature or slightly chilled (but protected from direct ice contact).
Ship the cooler to your CDC ELITE lab via overnight delivery. The lab must process the samples within 24–48 hours of collection.

Step 5: Digitizing the Results

Traditional laboratory culture testing takes 10 to 14 days, as the bacteria grow very slowly in petri dishes. When the results arrive (typically measured in Colony Forming Units per milliliter, or CFU/mL), you must attach this data to your compliance records.

Paper trails get lost. To ensure your facility remains legally defensible, use a platform like Legionella Compliance. Our software allows facility managers to digitize their entire testing schedule, instantly map lab results to specific floor plans, and trigger automated alerts if a sample comes back positive—ensuring that rapid remediation steps are taken immediately and documented permanently.