I feel like I should write a blog post about how toilets actually work and my recent adventure fixing a leak caused by siphoning.
Moving into my new place, I couldn't help but notice the toilet was running, you know, that constant water trickling sound? It's a pretty common problem, and I've tackled it in the past. Usually, it's just a worn-out rubber flapper – an easy fix that costs about seven bucks. But this time, in my recent move, that trick didn't work. The issue just wouldn't go away.
The constant water running drove me crazy, especially at night when that dripping noise seemed to echo through the house. Every now and then, I'd hear the water pump kick in, refilling the tank. Luckily, I never found water all over the bathroom floor, so it seemed like the leak was confined to the bowl.
Another usual suspect here is a worn-out gasket on the flush valve or even a crack in that overflow tube. The catch? Fixing those would be a real pain, involving taking apart the whole tank. To stop the ongoing leak, I did the simplest thing – shut off the water supply. But here's the kicker: the water level dropped, yet the tank didn't empty completely. So, it couldn't just be a worn gasket, but I was left scratching my head.
Fortunately, once I described the symptoms in detail to google, I figured out the culprit – 'siphoning.' So, I hit up YouTube with 'toilet siphoning' as the keywords, and there it was – the video that had all the answers.
In that video, they showed this thing called the 'refill tube.' It's basically a water pipe that you stick into another pipe known as the 'overflow pipe.' Now, here's where it gets tricky: if you jam that refill tube too far into the overflow pipe and its opening dips below the water level in a full tank, bingo, you've got siphoning. So, the fix? It's a piece of cake – just trim that refill tube or give it a little tug so that its opening always stays above the water level in a full tank.
I couldn't wrap my head around how simple the fix was. I was still scratching my head about how the toilet tank actually worked. Why in the world would shoving that refill tube too far into the overflow pipe cause siphoning? And seriously, why the refill tube needs to be shoved into the overflow pipe in the first place?
After looking at numerous toilet tank diagrams, I finally figured it out. However, as is often the case with engineering, the reason can always be bad naming.
The refill tube is actually part of the refill valve, which is hooked up to the water supply. Here's how it rolls: after you flush the toilet and the water level takes a nosedive, the refill valve kicks into gear, popping open to start refilling the tank.
Now, inside the tank, there's this other tube-like thingy called the overflow tube. It's hollow and links up with the bowl. If you over-fill the tank and the water level ends up higher than the overflow tube's opening, that overflow tube becomes drainpipe, guiding water into the bowl to prevent any bathroom flooding chaos.
So, why do they stick the refill tube into the overflow tube? I mean, they call it the "refill" tube, but they never really specify what it's refilling. To a rookie toilet engineer like me, it seemed like the tank was the only thing that needed a refill. How on earth could a tube connected to the overflow tube, which goes straight to the bowl, possibly have anything to do with refilling the tank?
My initial not-so-bright idea was that there's some fancy contraption in the overflow tube that switches the water flow between the tank and the bowl. But, honestly, that sounded like a needlessly complicated setup to me.
So, get this: the refill tube isn't about topping off the tank; it's all about making sure the bowl maintains its water level. You see, the refill valve has a sneaky second opening for pumping fresh water into the tank (fill ports). The whole deal with the refill tube is to keep the bowl's water level just right. Without it, every flush would leave the bowl's water level lower than when it started. That's why they hook up the refill tube to the overflow tube and the bowl.
That explains the siphoning issue. When the tank is all filled up and you jam that refill tube too far into the overflow tube, its opening can end up below the water level. That's the perfect recipe for siphoning, sucking water from the tank into the overflow tube. That's why you hear that annoying dripping sound. And as the leaks keep adding up, the water level gets too darn low, setting off yet another tank refill.