I recently got a phone call from a home owner asking me if a could increase the water level in the bowl of her 1.6 gallon toilet.  If you are a owner of a toilet with a low water level in the bowl, you know why she took the time to call me for a remedy. 
  Unfortunately, there isn’t a full bowl of water solution.  The level in the bowl is determined by the level of the trap in the toilet.  This is built in and can not be changed, any additional water will flow through the trap and the water level in the bowl will remain the same.  To keep flushes at the 1.6 gallons per flush, the manufacturers designed the toilets to have so much water in the tank and so much water in the bowl.  To find the maximum amount of water your toilet bowl can hold, take a bucket of water and slowly pour it into the bowl.  If the water level does not increase, there is nothing you can do, the laws of physics are stacked against you.  If the water level in the bowl increases to a maximum point, then you do have a couple of options.  One, you can adjust the flapper to stay open longer during the flushing process to the point of having a near “double” flush.  Doing this will increase the amount of water left in the bowl after a flush, and this gives the  bowl more water initially when the tank and bowl are being refilled.   This should cause the bowl to be filled to its maximum level.  2nd option, you could add on to the overflow tube.  Increasing  the height of the overflow tube (may only be an inch or two) will allow you to put more water in the tank.  This will add to the amount of time to fill the tank and increase the amount of water being put back into the bowl.  Once again, getting to that max water level for the bowl.  Thats all I have……….good luck.