Cooling tower legionella testing requirements: where they come from, and what a tower program looks like

Twenty searches a month, $15.53 a click, competition 0.38, and its parent query, cooling tower testing, at 30 a month and $3.97. The person typing the first one wants to know what they are required to do. The honest answer begins with a conditional, because there is no single national rule for legionella testing of cooling towers in the United States, and any page that states one as universal is describing somewhere in particular. This one describes where requirements come from, and what a tower testing program looks like when a facility builds one.

Three places a requirement can come from

Local law, in a minority of jurisdictions. A small number of cities and states have adopted cooling tower rules, New York City being the best-known example, typically covering registration of towers, a maintenance program, inspection, sampling on a schedule, and reporting. Whether your tower sits in one of them is a question with a checkable answer at the local health department. Second, the standard or guidance the facility has chosen to follow, most often the ASHRAE standard on legionellosis risk management and the guidance built on it, which frames a program rather than dictating a frequency. Third, the facility’s own water management program, an insurer, an accreditor, or a lease, any of which can impose testing as a condition. Most towers are covered by the second and third and not the first.

Why the answer is always conditional

Because the three sources change independently. A city can adopt a rule next year. The standard is revised. An insurer changes its conditions at renewal. A facility that wrote its testing requirement into the program with the source named next to it can update one line when the source changes. One that copied a frequency from a website cannot say where it came from, which is a poor position in front of an inspector. We will describe what rules tend to cover; we will not tell you which one binds your tower, because we do not know where it stands.

What a rule typically covers where one exists

Registration of the tower with the authority. A written maintenance plan naming the treatment regime, inspection schedule and responsible parties. Periodic inspection, sometimes by a qualified person as the rule defines one. Sampling for legionella at a stated frequency, with defined responses to results at defined levels, all of which are the rule’s to set and are not restated here. Record keeping for a stated period, and reporting of certain events. A facility in such a jurisdiction should be reading the current text, not a summary.

What a tower sampling program looks like

Defined points: the basin, the return or sump, and often the makeup, chosen and recorded so the same points are sampled every time. Neutralised bottles, because tower water carries biocide and an unneutralised sample keeps disinfecting itself in transit. Temperature and residual measured at the moment of sampling. A method named in the program and held constant. A frequency set by the program, from whichever source above applies. And a defined response to results, written before the first round rather than after the first surprise. How tower samples are taken is described under cooling tower testing.

Testing that the schedule does not cover

Start-up after an idle season. Return to service after a clean, the pairing set out in the cleaning process and where sampling fits. A change of treatment regime, or of treatment provider. A result outside the program’s limits, which triggers repeat sampling from the same points. A tower that has been running with a known fault in its dosing or blowdown. Each is an event the program should name in advance, with the sampling written next to it, so that nobody is deciding on the day whether a round is needed.

Testing and treatment are separate lines

The treatment provider doses the tower and monitors chemistry. Testing for legionella is the independent check on whether the chemistry is controlling the biology, and the separation between the two is the reason it is worth paying for, an argument made in full in cooling tower water treatment and legionella. A rule that requires testing usually requires it from a laboratory, and does not usually accept the treatment provider’s own field readings as the answer.

The record that satisfies any of the three sources

Registration where required. The program, with the testing requirement and its source written in. Sampling reports, per round, from a laboratory, with points, method and chain of custody. The response to each result, with the follow-up. Inspection and cleaning records. Together they answer the question every source asks in its own words: is this tower being managed, and can you show it? Where the program itself needs building, the shape of one that runs is set out in what running a program involves.