Dual-flush toilets have become increasingly popular in recent years due to their ability to conserve water. Unlike standard toilets which use the same amount of water for every flush, dual-flush toilets allow you to choose between two flush volumes – a full flush or a partial flush. This enables you to save a significant amount of water when just flushing liquids. But how exactly does a dual-flush toilet work and what are its main components?
Page Contents
How Does a Dual-Flush Toilet Work?
A dual-flush toilet contains two flush valves – one for liquids and one for solids. The liquid flush valve releases a smaller amount of water from the tank, while the solid flush valve releases the full tank volume. To flush a dual-flush toilet, you simply push the flush button once for liquids or twice for solids. Pushing the button lifts or depresses the appropriate flapper to start the flush.
Most dual-flush toilets offer a choice between a 0.8 gallon (3 liter) flush for liquids and 1.6 gallons (6 liters) for solids. However, flush volumes can vary across different models. The lower volume flush uses just a fraction of the water of a full flush, allowing you to conserve water every time you flush liquids. Over the course of a year, this can lead to significant water savings.
Main Components
While dual-flush toilets may seem more complex, they contain similar internal parts to a standard gravity flush toilet. The main components include:
Toilet Tank
The toilet tank stores the water used for flushing. It contains all the components that control and release the water into the toilet bowl.
Flush Valves
As mentioned above, dual-flush toilets have two flapper valves inside the tank – one large and one small. The smaller valve controls the liquid flush while the larger valve controls the full flush.
Float Ball
The float ball sits above the water level inside the tank. As the tank empties, the float ball drops down which causes the fill valve to open and refill the tank. This ensures the correct amount of water is refilled after each flush.
Fill Valve
The fill valve allows water to flow from the supply line into the tank to refill it after a flush. It’s controlled by the float ball.
Flushing Mechanism
This includes the buttons, levers or handles used to initiate a flush. On dual-flush toilets, there will be two of these – one for liquids and one for solids.
Overflow Tube
If the tank fills too high, excess water flows out through the overflow tube to prevent flooding.
Dual Flush Valve Designs
There are two main types of flush valve designs used in dual-flush toilet tanks:
Flapper Valves
Flapper flush valves consist of a rubber seal or flapper attached to a lift chain. The flapper seals the flush outlet when closed. Pushing the flush button lifts the flapper via the chain to start the flush. Flapper valves are simple, reliable and inexpensive.
Tower Valves
Tower dual flush valves contain a vertical tower that slides up or down to seal or unseal the outlet. Buttons on top of the tower activate the flush. Tower valves can provide improved efficiency and performance over flapper designs.
Bowl Types
Like standard toilets, dual-flush toilets come in different bowl shapes and sizes. The most common options are:
Elongated Bowl
Elongated bowls have an oval shape that extends further from the back wall. They provide extra room and comfort but require more space.
Round Bowl
As the name suggests, round bowl toilets have a circular bowl shape. They fit better in small bathrooms but provide less seating space.
Compact Elongated Bowl
Compact elongated bowls offer the extra room of an elongated bowl with almost the same footprint as a round bowl. This makes them ideal for fitting in small spaces.
Advantages of Dual-Flush Toilets
Dual-flush toilets provide the following benefits:
- Save water – Using the reduced flush for liquids saves around 25% of water compared to regular toilets.
- Lower utility bills – The water savings directly reduce your water usage charges.
- Environmentally friendly – Conserving water is good for the environment, especially in drought-prone areas.
- Quieter operation – Dual-flush toilets are typically quieter than other designs when flushing liquids.
- Versatile flushing – The two flushing options provide added convenience for handling both liquids and solids.
Things to Consider When Buying
Here are some things to keep in mind when choosing a dual-flush toilet:
- Flush performance – Ensure both flush volumes work effectively to clear waste and prevent clogs.
- Water savings – Check the liquid flush uses 0.8 gpf or less to maximize water conservation.
- Bowl shape/size – Consider the bathroom space and your usage needs.
- Ease of use – Opt for large, easy-to-identify flush buttons.
- Durability – Select a durable, quality model from a reputable brand.
- Certifications – Look for EPA WaterSense certification for high efficiency.
Installation
Installation of a dual-flush toilet is similar to a standard toilet. Here is an overview of the steps involved:
- Turn off the water supply and flush the toilet to drain the tank.
- Disconnect and remove the old toilet.
- Remove wax from flange and install new closet bolts.
- Set bowl in place and connect water supply line.
- Slide gasket between bowl and flange.
- Tighten bowl down using nuts and washers.
- Install tank, ensuring correct flush valve alignment.
- Connect water supply line to fill valve.
- Turn on water supply and test flushing action.
- Seal base with caulk if needed.
The process takes 1-3 hours for most DIYers. Hiring a plumber can make installation quicker and easier.
Troubleshooting Guide
Some common dual-flush toilet issues and how to fix them:
| Problem | Possible Causes | Solutions |
|---|---|---|
| Weak flush | Low water level in tank; clogged holes in rim; blocked trapway | Adjust float to increase water level; clean rim holes; use plunger to clear clog |
| Tank doesn’t fill | Clogged fill valve; faulty fill valve; float too low | Clean or replace fill valve; adjust float rod |
| Runs continuously | Flapper leak; refill tube issue | Replace flapper; adjust/clip refill tube |
| Loose bowl | Loose closet bolts | Tighten nuts on closet bolts |
For issues that persist, contact a professional plumber for repair assistance.
Conclusion
Dual-flush toilets provide a water-saving, versatile flushing option by offering separate flushes for liquids and solids. The key components include dual flush valves, a toilet tank, bowl, and flushing mechanism. Benefits include lower water usage, smaller utility bills, and quieter operation. When shopping, look for effective flush performance, bowl size/shape, and WaterSense certification. Installation is similar to standard toilets. With proper care and maintenance, a dual-flush toilet can provide many years of reliable, eco-friendly flushing.