Let Me Tell You What I’ve Seen Out There
If you’ve got a tankless water heater, you’ve probably heard it before:
“Flush it once a year!”
But does it really matter?
Or is that just something plumbers say to get another service call?
Let me answer that — as someone who’s opened up dozens of neglected units and seen what happens inside when they’re not flushed.
The Truth? Yes — and Especially If You Have Hard Water
Here in Sacramento and the surrounding areas, the water is hard.
That means it’s loaded with minerals — calcium, magnesium, and all the lovely stuff that sticks to metal parts inside your heater.
Every time you heat water, those minerals cook onto the inside of the unit.
Bit by bit. Day after day.
You won’t notice it at first.
But after a year? That “efficient, endless hot water” machine starts working harder. And slower.
What Happens When You Skip It?
Let me tell you a story.
We got a call from a homeowner who said their tankless heater was making weird noises and the water pressure had dropped.
It hadn’t been flushed since install — over 4 years ago.
When I opened it up?
- Heat exchanger: caked with scale
- Flow sensor: stuck
- Burner: covered in carbon
- Inlet filter: practically glued shut
It took over two hours to clean it all out.
The unit barely passed pressure testing afterward.
One more year — and it would’ve needed replacing.
“But I Didn’t Know It Needed Maintenance…”
That’s what most people tell me.
And look — I don’t blame them.
Tankless heaters are sold as “low maintenance,” right?
But low maintenance doesn’t mean no maintenance.
Your car needs oil changes.
Your heater needs flushing.
Simple as that.
What Flushing Actually Does
Some people think flushing is just “running some water through it.”
Nope.
When I flush a unit properly, here’s what happens:
- I isolate the system
- Hook up a submersible pump
- Run a descaling solution (usually food-grade vinegar or something stronger, depending on the buildup)
- Let it circulate for 30–60 minutes
- Clean filters, check sensors, inspect flame pattern
- Flush the system again with clean water
- Run and test — watching for errors or weird sounds
Done right?
That unit runs like new again.
Do I Recommend Once a Year for Everyone?
Mostly — yes.
But let me break it down:
- Hard water? → Yes, every year. No excuses.
- Softened water? → Maybe every 18–24 months, depending on usage
- Big household? Lots of hot water use? → Every year
- Vacation home? Used rarely? → You might stretch it a bit
But here’s the kicker:
If you’re not sure when it was last flushed… it’s probably time.
What We Do at Golden Valley Plumbing
We’ve serviced just about every brand out there — Navien, Rinnai, Noritz, you name it.
We don’t show up and spray water around.
We do it right — because the goal isn’t just to “clean it,”
it’s to keep your system running quiet, fast, and problem-free.
Not sure if your tankless heater needs flushing?
Call Golden Valley Plumbing — we’ll tell you honestly.
If it’s clean, we’ll walk away with a smile.
If it’s not — you’ll be glad we caught it now.
Final Word
Can you go more than a year without flushing your tankless heater?
Sure.
You can also skip dentist appointments and hope for the best.
But from what I’ve seen inside those units?
Annual flushing is the cheapest insurance policy you’ll ever buy.
