Toilet tank refill valve --- Why do they waste water sending water down the overflow pipe ?

Question

See Step 11 on this company's device --- http://www.fluidmaster.com/pdf/400a_instructions.pdf

They are sending water down the over-flow pipe which is water lost down the drain for NO GOOD REASON AT ALL. My neighbor has defied this instruction and directed the water to fill inside the tank instead and there is no ill-effect. The re-directed water filled up the tank faster. Why would a commercial company ask their customer to waste water ? There must be a good reason ... Anybody knows why ?

Guys, please note that the water down the overflow pipe does not fill the tank. It will begin to 'go down the drain' along the overflow pipe until the tank is full and floater shuts down the water supply. It is understandable to have an overflow pipe and it must be sized to avoid water supply not shutting off ... why the word 'over-flow' ... There is one suggestion that the water down the overflow pipe will prevent the toilet U shaped trap to be sucked dry, thus allowing odor to come up ... if that is indeed so, then if we defy the instruction, one should be able to see the toilet without the water remaining at the bottom which is part of this U shape trap. This is not the case at all. There are still plenty of water even if we direct this tube toward filling up the tank ...

Let us not forget that this company spent time and money, which could have been made into good profit for the company, into this 'diversion' ... and the instruction did use the word 'MUST' in its instruction

Answer 1

As mentioned, the water directed down the overflow is to refill the bowl.

The Reason:

The toilet bowl is also a trap (like a trap on a sink) where a quantity of water blocks sewer gasses from traveling back into the house. If there is an inadequate amount of water in the bowl after a flush it will be easier for these gasses to enter the home. The toilet by designn is a siphon which once flow is started down the drain the contents of the bowl literally get sucked down the drain with the rapidly draining water. The siphon continues until it is broken by sucking air at the end of the flush

This rapidly draining water flowing into the sewer/septic system causes pressure/vacuum disturbances along the lpipe system as the water drains. A vent pipe is installed to break the vacuum and allow the water to flow faster in the main line . Despite having the vent pipe these pressure disturbances still happen as the flowing water passes by other drain connections. If there is an insufficient amount of water in a trap it it is possible to have air bubble into the bowl and/or have additional water from the trap sucked out of the trap . (Low water level in a trap equals a weak trap seal)


If you feel that you must save a little water you may be able to adjust the water flow of the bowl fill. Some flush valves do have a screw adjustment for flow. Valves with copper tubing can be crimped slightly. And in the case where no other adjustment is provided you can direct the water stream at the edge of the overflow so that a portion of water goes into the bowl.

You do want to have some water go back into the bowl so that a proper trap seal is provided.

Answer 2

The bowl still needs to be refilled, up to the siphon line. You are correct in that any more water than is necessary to fill the bowl is a waste, but that is the technology that is available.

Since the metal clip that is used to point the refill tube down into the refill pipe is flexible, you could bend it so that some of the water is directed down the pipe, and some is directed into the tank. Experiment with the ratio of tank to tube directed water. That way you can get a full bowl without any waste.

PS. I am going to do that to my own toilets, now that you have pointed out this 'flaw' in basic toilet design.

.

Answer 3

This Site Might Help You.

RE:
Toilet tank refill valve --- Why do they waste water sending water down the overflow pipe ?
See Step 11 on this company's device --- http://www.fluidmaster.com/pdf/400a_instructions.pdf

They are sending water down the over-flow pipe which is water lost down the drain for NO GOOD REASON AT ALL. My neighbor has defied this instruction and directed the water to fill inside the tank...

Answer 4

That "overflow" pipe is the one that fills up the water level in the toilet bowl. It is why there is an appropriate level of water in there to get flushing started. Filling up the tank is only part of what you need to do for good flushing action.

If you reasoned it through you would have to ask yourself "Why would a commercial company go to the trouble of building in the tubing and the valving and the standpipe needed for that water to go into a pipe unless there was a good reason?"

When your defiant neighbor finds his toilet is not flushing well he might want to rethink his actions, hopefully before the sewage overflow reaches your house.

Answer 5

it's not wasting water...it's refilling the bowl. you should install the angle device with the clip onto the fill tube, and cut the tube to the correct length so you dont have to bend the tube and possibly restrict flow, and then install the tube so that flow is directed down the overflow. fluidmaster has these things figured out. they are the best. listen to them.