From the outside, a dual flush toilet looks like a regular toilet, but it has a couple unique features. There is no siphoning action when the toilet is flushed. The trapway, the hole at the bottom of the bowl through which waste and water exits, is larger in a dual flush toilet. This feature makes it easier for waste to be flushed and also reduces the likelihood of clogs.
Most importantly, the other key feature of a dual flush toilet is that the user can choose which type of flush to use—liquid or solid.
A dual flush toilet works by incorporating a flushing mechanism that regulates the water used in order to flush either solid or liquid waste. There are two dual flush systems that you can install yourself or buy pre-installed. The first dual flush valve is known as a toilet syphon which is controlled using a toilet handle. The other is know as a dual flush drop valve which is controlled by push button or lever handle.
Liquid waste needs much less help to exit the toilet bowl, meaning a liquid flush will use much less water. In most dual flush toilet models, a liquid waste flush is about a half flush and uses less than a gallon of water per flush. Because flushing liquid waste is the most common job for the toilet, a more water efficient flush can lead to many hundreds or even thousands of gallons saved in a year.
A solid waste flush uses about twice the amount of water as a liquid flush to ensure the contents will make it down the drain. However, because of the toilet’s larger trapway, dual flush toilets still use less water than traditional models.
A toilet has only one job—handling human waste and safely flushing it away from the home. Most toilets handle two types of waste, solid and liquid, the exact same way: the toilet bowl starts full of water, when it’s flushed it takes whatever is with it down the drain, and the bowl is then refilled with water. The toilet may need a full amount of water to flush solid waste, but liquid waste is more common and requires much less water per flush. Normal toilets can't adjust to the type of waste being flushed, meaning they often use more water than necessary. Dual flush toilets are a new trend in plumbing that increase water efficiency by differentiating between types of waste and adjusting water usage accordingly.
This will depend on the type of mechanism, but if it is a push button look for small symbols representing a full or half flush. A small flush is usually represented by a half circle or a water drop. If it is a lever handle then the appropriate lever. For liquid waste, select the half flush option and the full flush for solid waste.
Many homeowners find dual flush toilets can take some getting used to, even just remembering to press the right button and selecting the correct flush to use. They can be expensive, and the reduced water flow means they tend to get dirtier faster and require more frequent cleanings.
But for homeowners seeking a greener approach, installing a dual flush toilet is an easy way to conserve water and reduce water bills without a lot of effort. If you're looking for a more water efficient toilet or other appliance, keep your eyes open for the EPA WaterSense label. Your local Roto-Rooter plumber can also offer advice on this matter, as well as help you remove the old toilet and install the new.