It is true -- many cities have conducted a massive drive to replace older toilets with new water-saving models. Here's why...
A family of four can consume something like 300 to 400 gallons of water per day on things like bathing, cooking, drinking, laundry and dish washing. Old toilets use about 5 gallons (20 liters) per flush. When you consider that a normal person flushes a toilet seven or so times a day, you can see that a family of four consumes more than 140 gallons per day by flushing alone. Depending on the article you are reading, the water consumption of toilets represents between 30 percent to 50 percent of the water consumed by a household each day.
The new toilets installed in your apartment use 1.6 gallons (6 liters) per flush. If you replace those 5-gallon-per-flush toilets with 1.6-gallon-per-flush toilets, you save a huge amount of water -- something like 100 gallons per day per household. For a city, a big reduction like that means that you can delay the construction of new reservoirs and new sewage treatment plants. That's a huge incentive to replace all the toilets!
These links will help you learn more: