Where Does Sink Water Go? (2 Routes Explained!)

According to High Tide Technologies, the average American household washes down at least 50 gallons of water daily. Given that there are 27 million-plus households, you cannot help but ask, where does sink water go?

Ideally, sink water goes to the septic tank in your backyard or the municipal’s sewer line. In the first case, sink water seeps through the soil into the ground, while in the second case, it’s treated at a waste treatment plant and later reused.    

Overall, it depends on what connects your household drains. If it’s the septic tank, which is often the case of private homes, sink water goes to the septic tank.  And if your gutters lead to the municipal’s sewer line, which is often the case of most rentals, sink water collects in the sewer.

Note, however, that the septic tank and the sewer are not the ultimate destinations of waste sink water. Several steps are involved, ensuring the water comes back to the environment as clean water.    

To help you understand all that, I’ll discuss the two routes that sink water follows. Note that it doesn’t matter if it’s the kitchen sink or bathroom sink, as water from all sinks has the same destination.

It also doesn’t matter if it’s sink water, shower water, or toilet water, as all drains in your home either drain at the sewer or the septic tank.

Let’s get started!

where do sinks drain to

Where Does Sink Water Go After Washing Down?

Once you pour water down the sink, it follows any of these two routes:

1. The Septic Tank

A septic tank commonly found somewhere in your backyard holds wastewater from private homes. So, if you don’t depend on the municipal water supply or discharge, the chances are that you have a septic tank in your backyard.

In the tank are digestive bacteria that digest the wastes. They eat up the solid matter and leave out the liquid matter, which in the long run seeps into the soil as clean water and gets absorbed by plants.

The clean water can also contribute to the water table and become a part of groundwater, where it emerges as part of rivers, streams, and lakes. It then evaporates in the open and later comes back as rainwater, and the cycle continues.

Overall, a good septic tank should have active bacteria, facilitating a faster breakdown of organic waste. However, you can speed up things by using a septic tank treatment.

A septic treatment helps break down wastes quickly, maintain your septic tank, and prevent excessive repairs and backflows. Moreover, it eliminates terrible smells and works in your house septic tank and on boats and caravans.

2. The Sewer Line

If you stay in a town where you depend on the municipal water supply and wastewater discharge, your water drains (including the sink) empty into the sewer line.

In that case, water first passes through a p-trap, preventing gas backflow. Later, gravity pushes it down the drain into a Private Sewer Lateral (PSL), which delivers your house wastewater into the municipal mainline.

So, the municipal’s main sewer line collects all PSL wastewater and directs traffic to the communal wastewater treatment facility for treatment.

Where Does Bathroom Sink Water Go

What Happens to Sink Water at the Wastewater Treatment Plant?

A series of events happen to sink water, which is now part of the main sewer line wastewater (or sewage) before it gets released into the environment.

The events include:

a) Primary Treatment

In this first stage, wastewater goes through a physical screening process to eliminate large particles. That includes non-dissolving items like nappies, wet wipes, sanitary towels, among other large objects. After getting rid of the larger particles, wastewater goes to the secondary treatment.

b) Secondary Treatment

The second treatment stage involves the following events:

  • Solids Removal

Here, the sewage water takes time to rest and settle. In doing this, all the large solids sink at the bottom and mainly at the center.  With the help of rotating treatment arms, the particles sediment further before the liquid part moves to the next stage.

  • Biological Treatment

Not all large solids successfully go out in the first stage of the secondary treatment. Some smaller fragments may pass to this stage, which needs elimination.

Usually, the water passes through a biological treatment process to eliminate them. In this stage, live bacteria digest the remaining solid.

  • Disinfection Stage

After the bacterial digestion of organic matter, the wastewater goes through a chlorination stage. Here, chlorine disinfects the water to make it cleaner and safer.

Chlorine generally kills potentially harmful bacteria and other water microbes, making the water safer for reuse.

c) Advanced Water Treatment

This last stage ensures that the water is drink-safe and marine life-safe. In that case, the water (which we no longer call wastewater) goes through an advanced treatment to remove large amounts of phosphorus, nitrogen, and other potentially harmful elements.

What Happens After the Water Treatment?

Once wastewater is treated at a treatment plant and finally becomes clean and safe, it returns to the environment.  

The water may discharge into lakes and rivers to support marine life. It may also go into farms to irrigate crops. In some cases, the water finds itself into your tap for drinking and cleaning, and the cycle repeats.

Here are the events that take place after the water treatment:  

  • Evaporation and Rain

After discharging water to the water bodies (seas and lakes), it evaporates due to high temperature and condenses to form clouds. The clouds eventually come down as rainwater, which again collects in the water bodies, and some of it ends at the treatment plant. 

  • Rainwater Treatment

Once the rainwater collects at the treatment plant, it undergoes a thorough cleaning process. First, it passes through the screening process, where large solid objects like leaves and branches are removed.

Secondly, it goes through a filtration process to remove small and invisible particles. Lastly, the rainwater goes through the chlorination stage to kill any harmful water bacteria.

  • Pumping to Your Home

Once the water is safe for drinking and other domestic uses, it is pumped to your home through a piping system. That marks a complete cycle that repeats itself over and over again.

Where Does Kitchen Sink Water Go

Where Does Sink Water Go On A Boat?

Most boat sinks are connected to the toilet bowl to avoid flooding. So, the sink water goes to the toilet bowl and mix with the toilet water, which discharges through a waste hose.

Where Does Caravan Sink Water Go?

Caravans typically feature wastewater pipes for the sink, shower, toilet, and other drains. So, sink water goes through the wastewater pipes and gets discharged via them when it’s convenient.

Where Does Kitchen Sink Water Go?

The kitchen sink water either goes to the septic tank in case the drain connects to it or the sewer line, as it’s the case of municipal water lines. Sink wastewater goes through bacterial degradation and treatment before becoming safer for reuse in both cases.  

Where Does Bathroom Sink Water Go?

Like every sink water, bathroom sink water either goes to the septic tank or the local sewer line. It all depends on the connection. In either case, the wastewater goes through a detailed treatment process before returning to the environment through evaporation or direct pumping.

Does Wastewater Get Reused Again

People Also Ask  

1. Does Sink Water and Toilet Water Go To The Same Place?

Yes, your sink water, toilet water, and any water drain from your house go to the same place. Usually, some interconnected pipes in your home drain the wastewater to either a sewer line or a septic tank.

2. Does Sink Water Go To The Ocean?

Sometimes, the sink water discharges into water bodies, including oceans, after treatment. That, however, doesn’t happen to all sink water. For example, it’s impossible to do it when there is no ocean around.

Also, it only works with water that goes through the plant treatment process and not the septic tank route.

3. Are All My House Drains Connected?

Every drain pipe in your home is connected to the main drain. So, your wastewater from the kitchen sink, shower, toilet, washing machine connects to a large drain which takes the water to a septic tank or a communal treatment plant.

4. Does Sink Water Get Recycled?

The simple answer is yes, sink water is recycled. After wastewater from your sink goes to the communal sewage treatment plant, it passes through a vigorous treatment process to remove particles, odor, bacteria, and other harmful elements rendering it safe for reuse.

5. Why Is My Kitchen Wastewater Backing Up?

Your kitchen wastewater probably backs up because of dirt, grease, food, or hair clog accumulating in the sink pipes over time. The build-up causes a coating along the draining lines that restricts water from flowing normally.

6. Does Wastewater Get Reused Again?

Provided the wastewater ends up at a communal treatment plant, it will be reused in the long run. After treatment, the treated water is discharged into water bodies to support marine life, pumped into farms to sustain plants, or piped back into homes for domestic use.

Where Does Sink Water Go? Closing Thought:

Generally, it doesn’t matter if it’s bathroom sink water, kitchen sink water, or another as water from all home sinks either goes the septic tank or the communal sewer line.

From there, the water is treated and made safer for reuse. So, there is nothing like water wastage in the real world, as the water cycle takes care of everything.

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