How Does a Tankless Toilet Work?

Flush Technology

Once the handle is pressed on a standard tank toilet, gravity is the factor that exchanges water in the bowl with water from the tank. Tankless toilets, on the other hand, use a different type of technology, and because there is no tank they take on a completely different shape and look. Waste exits in the same manner as it does from a tank toilet: a valve opens and releases it into a pipe that leads away from the home or building and into the sewer lines. Tankless toilets use pressure and volume to pull clean water directly from the home or building's water pipes and into the bowl to replace what has been removed. Once the designated amount of water has entered the bowl, the valve closes and the flushing process is complete. This prevents the need for water to be stored in the tank because it is pulled directly from the plumbing.

Installation Issues

Tankless toilets refill quickly when flushed. The pressure needed for the flush is produced via a strong pump mechanism that runs on electricity. With a simple push of a button, the pump is triggered and the flush completed. The pump mechanism is enclosed within the bowl, and some models allow the water line to come up through the floor instead of the wall behind the toilet. Other models have a simple plumbing pipe that leads from the back of the toilet and into the wall to connect with the interior building plumbing. Or, like the industrial type, the plumbing rises up at the back of the bowl and connects through a T-shaped pipe to the plumbing. Although manufacturers will tell you that 1/2-inch pipes work fine with a tankless toilet, some newer models may require a larger pipe. Tankless models do not store water, and need to pull water into the toilet. If the pressure and volume are not adequate due to the size of the pipe used, the tankless toilet will continue flushing until it can obtain enough water to complete the process. A 1-inch pipe will solve this problem.

Advantages and Disadvantages

Supply lines may need replacing with a tankless toilet model. This is not a big issue when placing a tankless toilet in new construction, but may represent an additional cost when working with existing plumbing. An expansion tank may help with water-pressure issues, although installing one does defeat the purpose of a tankless toilet. Tankless toilets run on electricity. If the electricity goes out, the ability to flush is out as well. Saving space and water is the area in which a tankless toilet shines. Newer models may let you choose how many gallons are used in the flushing process. In general, they use about 1.6 gallons of water per flush, and because of their compact size, take up less space.