I recently installed a 1.28 gpf toilet replacing a five gallon toilet. This is the third one, none of them flush all the way down, leaves toilet paper in bowel. We put old one back in twice and it worked fine. If we pit a pitcher of water in bowel as we are flushing it will go down. Anyone have any suggestions on what to do???

It is something we would have to be there to do our own testing to determine what, if anything, can be done to make it work better.

Many Plumbers have good luck with Toto low flush toilets. Don't bother with the dual flush (two buttons one for liquid and one for solid waste) Google Low Flush Toilets that work and start your search there. Also I agree with putting a back water valve in the basement line. Sometimes the Plumber cannot get the correct amount of fall on a waste line or a belly could exist in a line that was improperly back filled. This belly forms a type of trap or resistance to proper flow and can cause blockages to build over time. Be a detective and try to understand your particular installation. Having a toilet that effectively moves the waste without using too much water is a good thing these days with the cost of water going up with no end in sight.

What follows is my signature on my emails. I worked as a Back flow Prevention Plumber at a Nuclear Plant in So Cal and wasting potable water was a real concern in those days.
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Manyfolks don’t realize what a Limited Resource Water is. As time goes by and the cost of water goes up, folks will start paying attention. Be Frugal with water use. LEAKS ARE EXPENSIVE! Check all faucets for leaks and
repair them ASAP.

Regardless of the size of the leak, it represents waste!
In worn faucet washers, toilet flappers, leaky sprinkler valves, ect.

Diameter of Leak Galllons Wasted Per Month

1/32 inch 4,800
1/16 inch 10,200
1/8 inch 76,900
1/4 inch 307,700
3/8 inch 692,400

Another way of wasteing water is to have the pressure set too high.
Your Pressure Regulator should be set to 50 PSI and checked with a gauge.
The higher the setting, the more water is wasted. A lower pressure is even
Better and you will use less water each month.

How old is your house and your plumbing system. You just might have an old house that was designed for the larger amount of water, based on the size, grade and material used. You might consider having a sewer camera sent down the line for inspection of your waste line and its integrity.

Best Wishes

Are the 3 toilets you installed the same make/model? Most toilets are rated for their flushing ability. You want a rating of least 600 and preferably 1000+. Here's a link for the testing organization, where you can search for ratings and info.
[www.map-testing.com]