How do I lower the water level in the fill tank. It presently overflows into the overflow tube. The water continues to flow. I read that the water in the tank should be 1/2 " below the overflow tube.

check that the fill valve was installed correctly
adjust the float level so that when full the cistern water level is around 1/2" below the over flow pipe end
what you have now is that the inlet water is not being shut off correctly and the water is still coming in and flowing out of the overflow

After flushing the toilet, water still fills the tank till then the shuts off valve reaches a certain level. When the shuts off valve reach the level it disconnect the water connection to the tank and the filling process of the tank shuts off.

So, if your fill valve didn't shut off then maybe there's a problem with the shuts off valve, open the fill valve and fix it. If you can't fix it call a plumber for it.

Troubleshoot Your Toilet Without a Plumber

www.popularmechanics.com/home/how-to/a4117/4303948/

Overflowing, constantly running and sweating toilets can test a home owner's sanity. ... take for granted--until we can't take a shower or make the toilet flush properly. ... If none of the above does the trick, you may have a misadjusted or faulty fill ... the waterlevel a half inch below the top of the overflow tube inside the tank." ...

Emergencies - Overflowing toilets - Toiletology 101

www.toiletology.com/emergenc.shtml

You can't just lower the water level in the tank; you need to displace some of ... and the ballcock and flapper are working properly and shut off when the tank is full. ... The bowl is filled with the water that goes into the overflow pipe. ... Unfortunately, when a toilet bowl is clogged and the water level rises and doesn't flush the ...

First is the water overflowing the overflow tube? This would indicate that the ballcock or flow master needs a seal or that it is rubbing the side of the tank (if it is rubbing the side of the tank twist it slightly). If the water level is always below the top of the tube but the flow master keeps on filling in bursts then you need to replace the flapper. Flappers will decompose slowly and black residue will come off to the touch. Wear gloves because this black will be on your hands for days. The flapper gets a slight ripple or curve that allows water to get by.

2 possibilities.1. The water level is set higher the the overflow tube. This will cause the water to run into the overflow continuously. You should be able to see this. 2. The large seal - bottom center of the tank - is leaking. This will cause the water level to slowly drop after a fill. The water tank will start to run again after flushing - BUT NOT CONTINUOUSLY. You should see if there is a small amount of water flowing from the rim to the bowl 15 seconds after the water has stopped running after a flush.

there are only 2 possibilities; 1 the tank seal is leaking into the bowl and the input valve runs to replace the water lost, or 2, the water inlet valve does not shut off totally and the water continues to flow into the bowl via the overflow tube in the tank.
If the water is running into the overflow tube, adjust / replace the input valve, if the water is not going into the overflow valve, clean / replace the flapper valve at the bottom of the tank.
Please let me know how you make out.

1- Check ports out under rim all round bowl.

2-Check tank fill level for required amount to with in 5/8" to top of over flow tube.

3-Make sure 1/4" fill tube is connected to over flow tube. From fill valve to overflow tube.

Below is a few details to go by I hope will be helpful for you to take care of this problem.


Under the rim of the bowl check the ports and make sure they are not stopped up. You can open them up with nail or pin to clean out ports.
Next check tank level and make sure the fill valve has a line run from it to top of the overflow tube. This line allows water to goe to bowl and tank to fill required amount needed.
Water in tank should be within 5/8" to top of over flow tube.

I don't exactly know what you mean so i will cover all the basics. The fill valve sends fills water in 2 locations. 1) the fill valve fills at the low end (from the bottom to the top) of the tank. This is the flush water level. It needs to be stopped by a float switch before the water overflows into the over flow tube.
2) the fill valve fills water via a small tube at the top of it which this tube NEEDS to be pointed into the overflow tube with a high arch. THIS water is filling your toilet bowl section to proper flushing height. If your water in your bowl does not reach proper height and someone removes this tube to aim it into the tank where the other water is stored, THEN you may have the problems you described and you will need to do several flushes to remove waste.
SO to reiterate 1) make sure your float cuts off and stops the filling cycle before the water flows into the over flow tube. This is done from 1 or 2 adjustment screws. and 2) make sure the small black tube is aimed down into the over flow tube with a good arch. The arch prevents back siphon.

the fill valve shut off level setting is too high. water in the tank is overflowing in the overflow tube. adjust fill valve to shut off at lower tank level

float is sticking make sure it is moving up and down.or the float is set to low, the lower the float is higher the water level is.