The five-year sprinkler inspection: internal pipe check, gauges and obstructions
Updated November 2026 · Bruhn & Bruhn Fire Protection
Every five years, NFPA 25 asks for a look inside the sprinkler piping for corrosion, sediment or anything else that could block water, along with new or calibrated gauges and an internal check of key valves. If debris turns up, a fuller obstruction investigation follows.
Why look inside the pipe
A sprinkler system can look perfect from the floor and still have pipe that's half full of rust nodules, scale or debris left from construction. When a head opens, that material moves with the water and can plug the very sprinklers that are supposed to control the fire. Microbiologically influenced corrosion (MIC), common in older wet systems, makes it worse.
The five-year assessment is how that gets caught before it matters.
What we do
- Open a flushing connection at the end of a main and remove a sprinkler near the end of a branch line, then look inside, with a camera where the pipe allows.
- Check for sediment, scale, corrosion, MIC and foreign material, and note the condition with photos.
- Replace or calibrate the system gauges.
- Inspect the internals of alarm valves, check valves and strainers, and, on dry and preaction systems, the valve interiors.
- Write up what we found, with photos, and whether an obstruction investigation is needed.
If we find debris
NFPA 25 then calls for an obstruction investigation: a wider look across the system to find how far the problem goes. Depending on what we find, the fix is flushing, replacing the worst sections of pipe, or, for corrosion that keeps coming back, treating the water or switching to nitrogen on dry systems. We explain the options and the cost of each before anything is done.
Frequencies here follow NFPA 25, 2023 edition. Your fire marshal or insurer may enforce a different edition or add requirements of their own; we'll tell you which applies to your building.
Questions owners ask
- Is the five-year internal inspection required?
- Yes, under NFPA 25 an assessment of the internal condition of the piping is required every five years, along with gauge replacement or calibration and internal inspection of certain valves.
- Does the system have to be drained?
- Usually only the sections we open. We isolate and drain what's needed, inspect, then restore and refill the system the same day.
Want us to handle it?
We do this work for commercial buildings across Middle Tennessee, North Alabama and Kentucky. See our sprinkler inspections service, or ask for a quote.