From 1950 -the early 1970’s toilets used 5 gallons of water

In  1980 toilets used 3.5 gallons of water

In the 1990’s-Present day toilets use 1.6 gallons of water.

In the Future they plan to use 1 gallon of water or less.

There are already some waterless fixtures out there now.

A 3.5 gallon toilet will rarely ever go totally bad they are virtually indestructible. Unless you break the vitreous china.

(They are made or cast molded from acid resistant porcelain.)

The parts however are altogether a different story. Most manufactures

don’t want to spend a lot of money on the inside product or the guts of it

as long as the tank parts last a couple of years, their warranty is covered and they're fine with that. More  

 first thing every one replaces when their toilet run's is 

the flapper. How many times has your toilet flapper been replaced?

Home and hardware stores as well as a lot of other plumbing companies

Will sell you an inexpensive flapper made of an even cheaper "rubber" than your original flapper.

Rubber out of water alone has an approximate 10 year shelf life?

Rubber in water has maybe 2 to 4 years, I have seen expensive

"long lasting" flappers go in 1 years time.

 Introduce Bowl cleaners into your tank such as round chlorine tablets

 or the "blue stuff" (more on Blue Stuff  later) cut's the rubber component life in half.

  The "Blue Stuff" turns into a gel like substance and through the passage of time it WILL fill the rim of the toilet clogging the water outlets slowly choking your toilet rinse, flush action off. To repair this flush out all this out of your tank and with a piece of wire poke the holes under the rim of your toilet while continuously flushing the toilet. I guarantee you will see an immediate and certain difference. Doing this activity can also help a toilet where water hardness has set in plugging these same holes.