Totally relate to that gauge paranoia—been there myself. Couple things I've noticed from my own battles with PEX and pressure:
- Even a tiny misalignment when you're crimping can cause weird pressure drops. Learned the hard way that eyeballing isn't enough; gotta make sure the fitting sits squarely inside the pipe before squeezing.
- Also, pipe cutters matter more than you'd think. Dull blades or uneven cuts leave burrs that mess with fittings seating properly. Switched to a sharper cutter and saw fewer issues right away.
- Another sneaky culprit: debris inside the pipe. Had a job once where pressure was erratic, turned out there was a tiny plastic shaving stuck inside from manufacturing. Took forever to track down...
PEX is definitely forgiving compared to copper, but it has its quirks. Attention to detail and double-checking everything pays off big time.
Had a similar problem a while back and went through pretty much the same checklist. One extra thing I found that hasn't been mentioned yet: checking the pressure regulator itself.
If your house has one, sometimes they start acting up without obvious signs. Had a job last year where the homeowner swore up and down they'd checked everything. Turns out their regulator was slowly dying—pressure would randomly spike or drop depending on how it felt that day, I guess. Swapped it out, and everything stabilized immediately.
Also, if you're using expansion fittings instead of crimps (the ones with the expansion rings), temperature can affect your install more than you'd think. Had a winter install once where we expanded the PEX in cold weather and didn't give it enough time to shrink back before pressurizing. Ended up with tiny leaks at fittings that caused weird pressure fluctuations until we redid those connections properly indoors.
And yeah, totally agree on debris being sneaky. I once chased phantom pressure drops for hours before finding tiny bits of construction grit stuck in an aerator screen—felt silly afterward, but lesson learned.
PEX is great stuff overall, but it's definitely got its own little gremlins hiding in the details...
"checking the pressure regulator itself."
Good call on the regulator—seen plenty of those cause intermittent headaches. One more thing I'd add: have you checked your main shut-off valve recently? Had a case where the gate valve was partially closed internally due to corrosion, causing random pressure drops. Swapped it out for a ball valve, problem solved. Makes me wonder how many times we overlook something simple like that...
"Had a case where the gate valve was partially closed internally due to corrosion, causing random pressure drops."
That's a great point about the gate valve—I had something similar happen at my parents' place last summer. They were complaining about weird fluctuations in water pressure, especially noticeable when running the shower or washing machine. At first, we thought it was just an old regulator acting up (house is from the late 70s, so you know how that goes...), but after swapping out the regulator and still seeing issues, we started scratching our heads.
Turned out their main shut-off valve was one of those old-school gate valves too. When we finally got around to checking it, it was pretty badly corroded inside—looked like it hadn't been fully open in years. Replaced it with a decent ball valve and instantly saw a huge improvement. Honestly, I never would've guessed something as simple as a valve could cause such inconsistent pressure.
Another thing worth mentioning—if you've got galvanized pipes anywhere in your system, they can also be sneaky culprits. Had a buddy whose house had galvanized lines that looked fine on the outside but were almost completely clogged with rust and mineral buildup inside. He chased his tail for months replacing fixtures and regulators before finally realizing the pipes themselves were restricting flow.
Anyway, definitely agree that checking valves and regulators is key. Sometimes it's easy to overlook these basic components when troubleshooting because we're expecting something more complicated or expensive to be the issue. Learned that lesson myself more than once...
"Another thing worth mentioning—if you've got galvanized pipes anywhere in your system, they can also be sneaky culprits."
Totally agree on the galvanized pipes. Had a similar headache at our place... ended up being rust flakes coming loose and clogging faucet aerators randomly. Thought it was valves or pressure regulators at first too, but nope—just old galvanized piping slowly falling apart. Switched to PEX lines eventually (budget-friendly DIY), and it's been smooth sailing since. Worth checking if you're chasing weird intermittent issues.
