Frequently asked questions about building water testing
The questions that come up most often, answered as briefly as they can honestly be answered, and, on the health questions, answered by pointing somewhere else, deliberately.
One thing before the questions
If your question is about somebody's health, it is not a question for this site. Contact your local or state health department and the clinicians involved. Everything below is about buildings and water systems.
Frequently asked
Does a negative result mean the building is safe?
No. It means the organism was not detected at those points, by that method, on that day. Safety is a property of a managed system over time, see what testing establishes.
Who is responsible for the building's water systems?
The owner or operator, with responsibilities frequently split in leased buildings. Settling that boundary in writing is a prerequisite to any workable sampling plan.
How often should we test?
At the frequency your program sets, and at any frequency a requirement imposes, which for cooling towers is more often prescribed than for domestic water. No frequency is published here.
What limits should results be compared against?
Those in your program or in the applicable requirement. This site publishes no thresholds or action levels, because a number quoted outside its framework is worse than no number.
Is a water management program required for our building?
It depends on the building type, the systems present and the jurisdiction, so ask your local health department or code official what applies. Where it is not required, it remains the framework testing is only meaningful inside.
Can we do the sampling ourselves?
Some programs do, with training and a documented procedure. Collection technique affects results, so it is a decision to make deliberately, see sampling and analysis.
How long do results take?
It depends on the laboratory method, and the difference between approaches is substantial. Ask at bid stage, because turnaround changes how a result can be used.
What do we do if a result comes back high?
What your program’s response plan says, which is why the plan is written before the sample is taken. Where illness is involved, public health authorities lead. This site interprets nothing.
Do cooling towers have separate rules?
In some jurisdictions, yes, registration, written plans, prescribed testing and reporting. The variation between places is larger here than anywhere else in this subject, see cooling towers.
We reopened after months of low occupancy. Where do we start?
With the program and a flushing regime, then a baseline round if the program calls for one. Low occupancy is one of the standard triggers to revisit everything.
Who takes the samples, and who analyzes them?
An environmental services firm takes the samples and a laboratory runs the culture. What this site adds is the part before that: it helps you scope what the building needs, passes the request to one qualified professional who covers it once you agree, and lists the laboratories on the CDC ELITE roster so you can check any of them. See how we work.
Last reviewed July 29, 2026.
Related pages
- Testing servicesUnderstand the service before buying it.
- Urgent situationsGet pointed to the right authority fast, then scope testing.
- Testing review requestAct.
- Plan builderProduce the document the obligation actually asks for.
- Accredited labsFind a laboratory that can actually run the culture, and know what to ask it.
Ask about a specific building
General answers only go so far. Describe the systems and the program status: we call you back to scope it, then, with your OK, pass it to one qualified professional who works on buildings of that type.
Free to ask, no obligation.