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NotMechanical · Jun 10, 2007, 08:28 AM

Can you tell me specifically WHERE the water comes from that fills the siphon that causes the toilet bowl to empty? All the cut-away pictures that I've seen don't show where this large amount of water comes from to start the siphoning action. I'm going nuts trying to understand this.

speedball1 · Jun 10, 2007, 10:05 AM

All the water used to flush a toilet comes from the toilet tank,(see image).
The older toilet tanks held 3.5 gallons, the newer ones only 1.6 gallons.
Next question! Cheers, Tom

speedball1 · Jun 10, 2007, 12:45 PM

Hi Tom! Would you be so kind as to answer one more question. What is the PATHWAY that the water (FROM the TANK) flows that WOULD CAUSE the toilet bowl water to be siphoned OUT. One explanation that I found on the Internet said, "The user activates a flushing mechanism which pours a large quantity of water quickly into the bowl." (Does this water come from the rim holes? ) It further stated, "This creates a flow large enough to fill the siphon tube, causing the bowl to empty rapidly due to the weight of liquid in the tube." I am so frustrated that I am not able to visualize this. It might have to do with the fact that I don't totally understand the "siphoning action." I will be SO GRATEFUL if you are able to walk me through this process -- where the water from the tank goes in order to cause the water in the toilet bowl to empty. THANKS!

speedball1 · Jun 10, 2007, 01:14 PM

Originally Posted by speedball1

Hi Tom! Would you be so kind as to answer one more question. What is the PATHWAY that the water (FROM the TANK) flows that WOULD CAUSE the toilet bowl water to be siphoned OUT. One explanation that I found on the Internet said, "The user activates a flushing mechanism which pours a large quantity of water quickly into the bowl." (Does this water come from the rim holes??) It further stated, "This creates a flow large enough to fill the siphon tube, causing the bowl to empty rapidly due to the weight of liquid in the tube." I am so frustrated that I am not able to visualize this. It might have to do with the fact that I don't totally understand the "siphoning action." I will be SO GRATEFUL if you are able to walk me through this process -- where the water from the tank goes in order to cause the water in the toilet bowl to empty. THANKS!!

OK! Follow along. The diagram I put up is called a siphon jet toilet. They also have washdowns and blow-outs but for a few differences they all work pretty much the same.
Start at the flapper. When you push the flush lever down it lifts the flapper allowing the tank to empty into the rim. The rim holes fill the bowl and start the swirling action. Notice the opening that starts at the "rim holes" and runs down to where it says "Outlet". That's the jet hole. Water comes out of that hole from the rim and it shoots up into the "Outlet" forcing the water in the "Trap" to go over the bend and start down into the "Drain". The water going down the bend sets up a vacuum while the water level from the bowl raises over the bend to begain the flush. The suction caused by the jet plus the weight of the water in the bowl completes the action. At that time the flapper falls down sealing the tank and the ballcock fills it ready for the next customer. Does that git it for you? Have a great weekend. Tom