Adjust the water level in the bowl of a duravit toilet

Remove and clean the flush valve and the flush valve seat(it is the flap that opens up to allow water to flush the toilet). Once the edges of the valve and the seat are cleaned, possibly with "0000" grit bulldog steel wool, it should not leak anymore. To make sure it is not leaking, once tank has refilled completely, put some food die in the tank. If, after 10-15 minutes, the water in the toilet bowl is colored, you have a leak from the flush valve. Replacing the flush valve is very easy - just bring the old one with you to the hardware/plumbing store and ask for a replacement. Blessings and good luck!!

Look inside the tank under the lid, it sounds like the flapper that lets the water into the bowl is getting hung up on something when you flush. It could be the flushing lever. This would cause the flapper to stay open letting water to just pour into the open sewer line. It should be a simple fix. Just see what is binding the flapper & make an adjustment.

The level is determined by a floating device connected to the water valve. Some are on an angled arm and some move up and down.
Determine how your valve is shut off and either change the big round float or adjust the clips on the rising one.
Just keep the level below the overflow and the flush handle to avoid a running toilet or a leak.

All toilet bowls have a preset water level determined buy the design of the internal s-trap and can not be change. However if the water level in the tank is not as high as it should be this will affect the water put into the bowel as the bowel in refilled by the flush valve and if it is set to stop before it get filled to the proper setting the bowl water level may be low.
A quick test is to see if the water level in the tank is up to the line in the tank most all toilet tanks have a line either stenciled or marked with a indentation in the porcelain. Another way is to mark the level in the bowel with tape or a marker then pour water slowly into the bowel not fast enough to flush it wait to see if it stays higher then the mark you made or settles back to that level.

A fairly easy ( but messy ) fix - get a replacement tank to bowl gasket and bolt kit, shut off water supply, drain tank, remove bolts ( you might have to cut, depending on your water source and minerals in your water). Remove old gasket and clean surface with 00 grade steel wool. Replace gasket, install new bolts, remount tank.
Good luck!!

if you can see the water running in the bowl it's a good chance that the flappers warn http://www.aplumbers.com/residential/toilet
1. tank the tank lid off.2. flush the rubber thing that comes up and allows the water to go to the bowl is the flapper 3. remove 4. replace that should fix it.
problem 2
1. tank tank lid off.2. if the waters flowing over the long tube in the center and down then the water level is too high3. adjust the level either it will have a ball **** or a float in either case   a ball **** adjusts by a screw on the fill valve. the float has a either a metal rod w/ a pinch clamp or a plastic long screw type thing.4. adjust water level .5. barely lift handle to allow a little water out til fill valve kicks on then release handle til valve stops .6. just keep re adjusting til you get the water level right there should be a molded in line for the level on the back of the tank.

The push button siphon assembly is worn out. Just replace it entirely.

install a fluidmaster flush valve.

The water level in the bowl is limited by the height of the internal trap down stream from the bowl. There is no adjustment possible. If the problem is odors, you can either flush more often, turn on the exhaust fan, or buy a different brand or model of toilet.