It started in late May
A large hospital in the Southwest — where summer temperatures routinely hover above 100 degrees — began noticing something strange inside their Sterile Processing Department. Sterilizers that had been running perfectly in the spring were now faulting. Not every cycle. Not every day. Just often enough to create frustration.
“Call the technician,” Facilities said. The technician came out. Checked the pressure. Checked the steam. Checked the gauges. “Everything looks fine,” they reported. And for a while, it was. Until June. Then July.
By mid-summer, cycles were failing almost daily. The vacuum pump had been replaced. Twice. Still, the problem lingered. That’s when they called Len.
The Slow Climb
When Len arrived, nothing appeared obviously wrong.
Water pressure? Stable.
Steam quality? Acceptable.
Equipment age? Within range.
But Len had heard this pattern before — the seasonal creep.
“What’s the temperature of the incoming utility water?” he asked.
Facilities paused. “The temperature?” They were monitoring pressure. They were checking conductivity. They were logging monthly water reports. But no one was logging incoming water temperature. In this part of the country, municipal water lines run shallow. By midsummer, the water entering buildings was no longer cool groundwater. It was warm. Sometimes in the high 80s. Sometimes even hotter.
The Hidden Role of Utility Water
“Your sterilizer uses steam,” Len explained. “But it doesn’t only use steam.”
Many sterilizers rely on utility water to:
Cool vacuum pumps
Support Venturi vacuum systems
Assist with pneumatic functions
When incoming water temperature climbs, vacuum pumps struggle to dissipate heat. Efficiency drops. Internal components fatigue. The pump doesn’t fail overnight. It slowly loses capacity.
“Think of it like trying to cool a car radiator with warm water,” Len said. “Eventually, something gives.”
And it had.
The Municipal Curveball
There was another twist.
As drought conditions intensified, the municipality had switched water sources — from reservoir to river. That shift brought a subtle increase in pH. The hospital never received notice. Conductivity began drifting upward. R.O. membranes that had performed flawlessly in winter were now allowing slightly more ions to pass through.
Nothing catastrophic. But enough to strain the system. Water, as Len often says, is dynamic. It is never static. And this hospital had been treating it like a fixed variable.
The Map They Never Drew
ANSI/AAMI ST108 emphasizes understanding water behavior over time — not just snapshot testing.
Monthly testing can miss mid-month fluctuations.
Daily logging of:
pH
Temperature
Conductivity
Utility water variability
creates a behavioral map. Without that map, you’re guessing.
“First rule,” Len said, “you can’t solve a problem if you don’t know you have one.”
The hospital began logging daily temperature and pH. They adjusted cooling strategies. They recalibrated monitoring frequency. They modified preventative maintenance timing for summer months. The failures stopped.
The Lesson
Nothing was “broken.” Nothing was “installed wrong.” The hospital hadn’t been sabotaged by equipment. They had been sabotaged by summer (and by assuming water behaves the same in July as it does in January).
Next Case File:
What other invisible variables are changing in your department — right now — without you knowing?
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