I came downstairs one morning to find my APEC RO-90 reverse osmosis system had leaked into my basement overnight. Lost some shelving, a few board games, and had a genuine mess to clean up — all sitting right underneath the unit. Here’s how I actually tracked down the problem, what didn’t fix it, and what finally did.
Diagnosing the leak
The system has three filter stages down low and two more up top, and the drip was coming from up near the top — somewhere around the tubing or the housing itself. I pulled the whole unit down to get a clear look, and found a small drip coming from a threaded port. It looked like the fitting wasn’t fully seated.
What I tried first (that didn’t fix it)
My first theory was a simple one: a John Guest-style threaded fitting that looked slightly unscrewed. While I had things apart, I went ahead and changed all five filters, replaced the O-rings with fresh food-grade grease, and wrapped the suspect threaded fitting in PTFE tape before reassembling everything.
I let the tank fill and ran it for a few hours, confident that was the fix.
It wasn’t. Still leaking from the same spot.
What actually fixed it
After a few back-and-forth messages with APEC’s support team, I ordered the filter housing cap assembly — a pre-built replacement for the entire top housing, fittings included. Once I swapped that whole assembly in, the leak stopped completely. Turns out the issue wasn’t a single loose fitting — it was the housing cap itself.
Redesigning the setup to prevent it happening again
Fixing the leak wasn’t enough for me — I wanted to make sure that if it ever happens again, it’s a minor cleanup instead of a repeat disaster. So I made a few changes:
- Remounted the whole system lower, closer to the basement floor instead of up near the ceiling
- Added a boot tray underneath, angled toward the floor drain
- Drilled a small drain hole near the edge of the tray so any future leak has somewhere to go
- Installed a YoLink water sensor inside the tray to catch a leak early next time
- Cleaned up and clamped the tubing so nothing’s loose or under tension
Parts & tools used
Everything I used for this repair and the redesign:
OEM Housing Cap Assembly (the actual fix)
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