Sunrise Specialty » Where Does Toilet Water Go? (13 Stages)

Where Does Toilet Water Go? (13 Stages)

Ordinarily, one of the least thought about things in a home or building is its toilet water. But when you eventually think about toilets systems or specifically consider where toilet water goes, it suddenly becomes imperative to discover the magic behind the curtain.

Don’t rack your head too hard trying to figure it out; it’s really not that technical. In this article, we’ll explain the mystery behind the disappearance of your toilet water, its destination, and its eventual usefulness, if any.

What happens when you flush?

What happens when you flush

Every house generates wastewater. The wastewater includes dirty water from your kitchen, shower, laundry room, and of course, your toilet.

All the aforementioned wastewater—including other things such as dirt, paper, soap et cetera—flows down the drain and move into the sewage pipes linked to your house or building.

This waste is often regarded to as sewage! We will go through each stage from how water gets into your tank to everything that happens after you flush.

Indoor Stages

All the processes in the toilet water journey that happen inside your house include:

Stage 1: The Refill

Stage 1 The Refill

As you already know, your toilet is connected to a water supply. If your tank is empty, a refill valve opens up to allow water into the tank through the refill tube.

A float inside your tank is also raised while it fills up and it eventually halts the process when it is totally raised. This is the first stage of the toilet water journey. Depending on your water supply, this should take less than 1 minute.

Stage 2: The Flush

Stage 2 The Flush

In the case of flushing toilets, a flush valve is raised when you push the lever and water from your toilet tank empties into the toilet bowl. Dual-flush toilets usually have two buttons that release different quantities of water instead of a lever.

By design and with a little help from gravity, the water pushes the excreta or liquid waste in the toilet bowl down into the toilet trap. Flushing takes about 15 seconds for most toilets.

Stage 3: The Trap

Stage 3 The Trap

The trap carries the toilet water and the accompanying waste into the main drain. After flushing, some water remains in the curved trap to prevent odors from sewer gas from entering your room.

Stage 4: The Drain

Stage 4 The Drain

The drain is a collection of pipes that connect your house to the sewer main where all the wastewater from your home is collected.

Your toilet water joins wastewater from other parts of your house and those from other houses and it journeys into the sewer pipes that are below your community and are about 3 to 5 feet in size.

This is the end of the journey in your house. The process generally relies on gravity to work.

Outdoor Stages

Outdoor Stages
Image: xylem

Wastewater cannot be allowed to contaminate the soil. It must be treated and converted to clean water before it either released into the soil or reused for irrigation, agriculture, or fishery.

If you have a personal septic system with its own septic tank, your wastewater flows into the septic tank where it is treated and disposed into the soil. However, septic systems are mostly used by houses that are too far from municipal water treatment systems.

This process applies only to the wastewater collected into the municipal waste treatment plants. Different levels of wastewater usually require different treatment processes.

The intended use of the water after the treatment also determines the treatment process. Typically, in order to treat wastewater and make the effluent useful, it is subjected to the following procedures:

Stage 5: Odor Control

Since sewage is usually laden with offensive odors, chemicals must be used at this stage of the process to subdue the stench before treatment begins. Some treatment plants also use deodorizing misting systems to control the odor form the sewage.

Stage 6: Screening

When wastewater is passed through screens, it gets filtered, and larger solids are separated from the sewage. Diapers, sanitary pads, wipes, bottle caps, and any solid that can clog the pipes or damage the equipment are also removed.

Stage 7: Primary treatment

Wastewater (your toilet water included), is moved into huge circular settlement tanks where the solids are allowed to settle at the base over time. The settled materials include human waste and are referred to as ‘sludge’.

Scrappers are installed at the base of the round tanks and they help push the sludge into the center where it can be removed and later treated. Your wastewater is now almost devoid of solids and sludge and can be moved into secondary treatment tanks.

Stage 8: Aeration

The water is stirred in rectangular tanks so the gases may be released into the air.  Air is also pumped into the tank to create an enabling environment for bacteria to decompose small organic material that may have not been scrapped in the primary treatment phase.

Stage 9: Sludge Removal

Leftover solid materials that settle at the bottom of the water are removed. This is done in a settlement that is also equipped with scrappers to facilitate sludge collection for treatment. The sewage now has only a small amount of sludge, chemicals and dangerous substances, if any.

Stage 10: Additional Filtration

Natural soil treats any contaminated water before it sinks, but it can’t handle all levels of contamination. Partially treated sewage is filtered through sand beds to remove smells, iron, bacteria, and other solid materials.

Stage 11: Heat Solid Materials

Heating the solids breaks them down into methane gas and biosolids that are rich in nutrients. All the solids and sludge collected in stages 6, 7 and 9 undergo this treatment.

Stage 12: Disinfection

Finally, chlorine is added to the water to kill bacteria and make it available to be reused. This final stage is required for effluents that will be used in irrigation or on agricultural land.

Stage 13: The Release

Finally, your toilet water has completed all treatment processes and is now released into the river where it may do no harm. This is the end of its journey!

The treatment systems for personal septic systems also use similar sedimentation techniques before treating and disinfecting the effluent. After treatment, your wastewater is disposed into a drain field or disinfected and used to irrigate your lawn.

What You Can’t Flush Down the Toilet

What You Can’t Flush Down the Toilet

When it comes to what you can and can’t flush, the benefits of following the rules serve you, your neighbors, and the environment.

Flushing the wrong items can cause your pipes to be blocked which in turn affects your neighbors who are also connected to the same municipal system.

Some items are also generally harder to decompose in the processes described above. Don’t flush these items:

  • Baby wipes, wet wipes, or any type of special wipes for that matter.
  • Eggshells (or any type of shells)
  • Napkins
  • Hair
  • Drugs
  • Any kind of plastic
  • Dental Floss
  • Fats and oils
  • Facial Tissues

Follow our simple rule of flushing; Flush only the three Ps: pee, poo, and (toilet) paper.

Toilet wastewater and its importance

Toilet wastewater and its importance

Given that clean water is essential for human living and survival on the planet, processed wastewater is also a valuable resource, especially with recurring droughts and water shortages in many parts of the world. Wastewater is important for two main reasons:

1. Restoring the Water Supply

If you take a glance at the rate at which global drought map had risen, you would realize that many parts of the world do not have enough clean water.

Communities with water scarcity need to make sure they are well equipped with proper water treatment processes so that treated water can either be reused or returned back into the water cycle, but never wasted.

2. Protecting the Climate

Obviously, toilet wastewaters contain contaminants and chemicals emanating from its residential and commercial use. If left untreated, the chemical compounds and other pathogens in them can cause harm to the health of plants, animals, and birds that live in or near the water.

When the water is to be released back into the soil, the quality of the effluent must be high enough to support plant and animal life in order to correct the climate imbalance.


Your toilet water doesn’t just disappear, depending on your sewage treatment system, it is processed to a level where it is safe for re-introduction into the soil or rivers without the risk of contamination.

If there’s anything you would like to ask us or if you want to make contributions, please leave a comment below, and we will be happy to reply.