Category Archives: Wastewater

A Foul Odor Outside May or May Not Be Wastewater

Have you ever ventured outside and something quite astonishing assaulted your nose? It may be easy to pin the blame on a wastewater treatment plant that could be nearby. However, foul odors commonly emanate from a variety of sources in our community:

  • Landfills
  • Industries (i.e. paper or chemical plants)
  • Natural gas pipeline work
  • A wastewater spill
  • Wastewater plants
  • Even private plumbing

Let’s start inside the home…

Private plumbing systems are designed to prevent wastewater gases from entering residences. All active sewer lines contain gases, and a malfunctioning plumbing system could allow gases or odors to enter the home.

Is the odor inside?

Is the odor only coming from…:

A drain that hasn’t been used recently?

We recommend for you to pour a gallon of water down the drain and see if the odor persists.

Multiple drains that are used frequently?

It may be a blockage or clog in your plumbing. Try a liquid dissolvent, please follow directions and see if this clears the clog and dissipates the odor.

A kitchen sink?

Clean the disposal (following the owner’s manual).

What you put down the drain (grease, oils, wipes) can cause odors clogging your plumbing. If the odor does not go away and is only inside your house, consider having a licensed plumber check your plumbing and vent system.

illustration of sink showing that water sits in the trap keeping gases and odors from coming out of the drain. Houses have a vent to the room so that any odor will escape outside.

Odor Outside Home?

Every home has a wastewater vent (on the roof) that could be the source of an odor immediately outside your home (patio, deck, etc.). The odor could be caused by a clog or blockage in your plumbing. Check with neighbors to see if they are also experiencing the odor. If it is only noticed just outside your building, contact a plumber.

Another place to check is in your front yard. Most homes also have a white plastic lid called a cleanout, and that if not closed properly it may cause odor in the yard.

If you live on waterfront property or the road is higher than your house, you may have a low-pressure sanitary sewer system to pump your wastewater up to the gravity fed sewer system. It is possible that this system may be causing an odor in the pump basin if something is malfunctioning.

What Can Cause A Wastewater Type Odor?

Sewage odor may be a sign of a nearby wastewater overflow that needs immediate attention.

​If you see or suspect a wastewater overflow or spill, call 311 or 704-336-7600 – 24 hours a day, seven days a week. If calling after hours, please say or select ‘wastewater emergency’ to speak to our dispatchers.

If you live beside a wastewater treatment plant, there may be some occasions when a smell is noticeable outside the property. Wastewater odor can be noticeable during warm temperatures, buildup of debris in pipes, or low flow during some nights and weekends.

CLTWater Takes Odor Seriously

For decades, wastewater treatment plants that were once neighbors to farms and forests are now neighbors to residential neighborhoods and businesses. In fact, there’s a wastewater treatment plant in the Little Sugar Creek / South Park area! As people moved closer to our plants, CLTWater invested millions on odor reduction. We aren’t baking bread, but we try hard to make the treatment of our community’s wastewater less noticeable.

Air scrubbers, carbon filters, bio-filters, help CLTWater reduce odors that can occur during the wastewater treatment process. We are committed to safely treating wastewater and reducing odors. We appreciate your input to help us identify potential odors.

How Do I Report an Odor or Sewer Spill?

If you see or suspect a wastewater overflow, call 311 – 24 hours a day, seven days a week (say or select wastewater emergency).

  • Try to locate the source.
  • If it is coming from a manhole or a creek, call 311 or 704-336-7600 and provide the closest address.
  • A repair crew will respond quickly, investigate the cause and repair any publicly owned pipes, if needed.


Why Does Wastewater Cost More On My Water Bill?

Treating wastewater is complex, using sophisticated biological systems, multiple filters, and modern disinfection methods.

So why does your sewer part of the monthly bill cost more than water usage?

The Short Answer:

It is easier and cheaper to treat lake water to make it drinkable than to treat the community’s wastewater (industrial, commercial, and residential) and make it clean enough to reintroduce into a creek or river.

Water leaving the plant must be free of harmful pollutants to protect fish, turtles, birds, and other creatures that depend on the creek.

Below is a step-by-step guide for turning lake water into potable or drinking water.

And here are the steps to turn your wastewater into creek-able water.

There are more steps to the wastewater treatment process than water treatment process.

Charlotte Water (CLTWater) only uses water meters to measure usage, so wastewater usage is calculated based on that water usage up to a limit or cap.

Energy and chemical costs are higher for wastewater treatment processes, hence the higher cost for wastewater treatment vs. water treatment on a water bill.

The cost to treat wastewater and meet federal regulations continues to increase. Our goal is to always meet and exceed regulations to ensure cleaner water goes into our creeks.

Stop right here if you’re satisfied! The Longer Answer gets a bit technical about how your billing works.

The Longer Answer:

CLTWater pays for water and wastewater services via usage and billing fees, not taxes (contrary to popular belief). CLTWater posted the official Revenue Manual that details all fees.

How can I help reduce my water / sewer bill and rate increases?
Toss all trash in the trashcan, not down a drain. Did you know that ‘flushable’ wipes clog pipes and require manually pulling them out of pumps? Wipes can cause expensive repairs and maintenance.

Additional resources:

What Happens When I Flush? A Story About Your Poop…

It isn’t magic, it is your water bill working for you…

When you wash, brush, or flush, the water leaves your home and flows mostly by gravity down pipes to one of our wastewater treatment plants.

There are over 4,600 miles of pipe used to collect the wastewater in the collection system. Utility crews clean pipelines to prevent blockages and spills. They also clear blocked pipes, maintain pumping stations, repair damaged pipes, and connect new customers. Our plant operators work 24/7 to protect public health and the environment.

What is wastewater, and where does it go?

Used water (wastewater) from inside homes and businesses flow through thousands of miles of pipes to one of five wastewater treatment plants. The used water includes detergents, food, paper, and industrial & human waste. The collection system includes pipes, manholes, and pumping stations.

But how does it all work? Below is a quick explanation:

Pumping Influent

Wastewater flows by gravity from homes and businesses to the wastewater treatment plant. It enters the plant at a low elevation, usually near a creek. The wastewater is pumped uphill to begin treatment. Gravity moves water through the treatment process.

Preliminary Treatment

Screens remove large objects such as bottles,  branches, wipes, and trash. Grit chambers remove grit, sand, sediment, and gravel.

A big part of the wastewater treatment process is to separate the solids from the liquids and the liquids from the solids…


Primary Treatment

Wastewater flows slowly through large tanks called primary clarifiers. This allows the heavier organic solids to settle down to the bottom of the tank. The settled material or primary sludge is pumped from the tank to a digester for further treatment.

Secondary (Biological) Treatment

Air bubbles are forced through the wastewater to encourage certain types of useful bacteria and microorganisms (microscopic single-cell organisms, think amoeba) to grow. These ‘bugs’ consume organic pollutants in the wastewater. They break pollutants (i.e. ammonia) into simpler forms (nitrates).

Final Clarification

The bacteria and microorganisms from the biological treatment phase are settled out of the wastewater in large tanks called final clarifiers. The bacteria/bugs are reused again in the treatment process…

Very similar to the primary clarifiers, the water moves slowly to allow the settling process to occur. Settled material or sludge that is pumped from the bottom of the clarifiers goes to digesters for further processing.


Even though the wastewater flowing from the final clarifiers appears to be clear, there may be very tiny particles remaining. The flow is passed through a bed of sand or fine mesh screens called an effluent filter. This filter removes these particles.


The processed wastewater (effluent) is disinfected with ultraviolet (UV) light to neutralize any remaining harmful microorganisms.

Cascade Returns Water to Creek

The final stage of treatment is disinfection and then the water flows over a cascade of steps to the creek. The cascade steps looks and acts like a large waterfall putting oxygen from the atmosphere back to the water. The water may have a foam look as it travels down the creek due to the oxygen.



Digesters are large tanks where the solids removed from the clarifiers are heated, mixed, and treated with biological processes to remove harmful bacteria, break down fats and oils, and overall reduce the volume of solids. 


The solids removed from the digesters still contain a large amount of water. This water is removed for treatment. The treated biosolids are collected and returned to the environment. The biosolids are nutrient-rich byproducts of wastewater treatment. Biosolids are land applied on agricultural or farmers’ fields to as soil amendments and a source of fertilizer. 

Wastewater treatment operators and our laboratory professionals test both the water and solids throughout the process.

Did you know…

  1. Our oldest plants were built in the 1920s.
  2. Part of designing for treatment plants includes ensuring space for expansion for generations.
  3. Staff can take parts of the wastewater plant offline for cleaning, repairs, and upgrades all while treating the constant flow.

Additional resources:

What does a growing city mean to wastewater treatment plants?

Why does wastewater cost more than water on my bill?

How does CLTWater respond to a wastewater overflow?

Is the odor from a wastewater plant or sewer manhole?

What is a Backflow Prevention Assembly? Why does my house have a backflow preventer?

As we move into the summer months, it’s good to know how different aspects of your yard and lawn maintenance can impact our water system.

If your home has an irrigation system, it is required to also have a backflow prevention assembly. A backflow prevention assembly is typically part of an irrigation system or commercial property.

This is an important step to protect the drinking water supply in your neighborhood. A backflow prevention device ​prevents hazardous substances (i.e. chemicals used for lawn improvement or soil borne bacteria and parasites) from inadvertently being drawn into the drinking water system and contaminating it. 

If you have any questions or if we can assist you, please call 311 or 704-336-7600. Thank you for your cooperation.

Commonly Asked Backflow Questions

How often do I need to have my backflow tested?

Annually. A list of approved testers is listed on our website.

How do I know when is my backflow test due?

It is due the same time each year unless a deferment is granted. We check the last time it was tested and provide that information in the annual “Test Letter.” We can provide that to the customer by phone.

Is backflow testing performed by Charlotte Water?

Charlotte Water only performs an initial installation inspection and any follow-up required. It is the responsibility of the water customer to get the backflow assembly tested. For a list of approved testers, please see a list on our website.

How much does a test cost?

Charlotte Water does not set pricing for backflow assembly testing. Customers need to ask individual vendors what their charge is for testing their backflow assembly.

My residential irrigation system backflow is due for testing in December, can I delay testing until the spring?

Yes, please contact Charlotte Water for a deferment on the testing date. We recommend you have your assembly tested in the spring once the irrigation system is reactivated following winterization.

I have a backflow and so does my neighbor, however, my neighbor has never received a testing notification letter, why?

Your neighbor installer may have not contacted Charlotte Water about the installation of the irrigation system.

Where is my backflow?

It is the responsibility of the water customer to know the location of the backflow prevention assembly for their water system. Charlotte Water has locations based on initial inspection details.

My backflow needs repairs, do I need to hire a licensed plumber to make the repairs?

Yes, a licensed plumber is required per the N.C. Plumbing Board. You should hire a licensed plumber or professional who has expertise in repairing backflows. 

What is the difference between a backflow inspection and a backflow test?

A backflow inspection is an onsite visit by a Charlotte Water Backflow Inspector, making sure the assembly is installed properly.  A backflow test is to make sure the assembly with working properly. Charlotte Water does not perform backflow tests for its customers.

I understand backflows are for high hazard facilities such has hospitals and mortuaries, however, why do I need one on my residential irrigation system?

Irrigation systems can encounter contact with fertilizer, pesticides, and feces, which are high hazards.  A Reduced Pressure Principle Assembly (RP) backflow is used for high hazards.

I have a double check valve assembly (DCVA) backflow that needs replacing for my lawn irrigation system, can I replace it with another DCVA?

No, per Charlotte Water ordinance, the correct backflow preventer for irrigation must now be an RP(Reduced Pressure Principle Assembly). This applies to new installation and replacing a backflow on an irrigation system.

My irrigation system is no longer in use, do I have to test it?

Annual testing is still required until a licensed plumber has capped off your water service at the connection and removed the backflow prevention assembly. An inspection by a Charlotte Water Backflow inspector is required.

Installation Questions and Answers

Do I need a plumbing permit when installing a backflow?

Yes, please contact the Mecklenburg County Code Enforcement at (980)314-2633, You will also need to complete a backflow service application.

Do I qualify for a branch of my irrigation system from my domestic service without a separate water meter?

The Plat date determines if you qualify. The property must be platted prior to 2009. Research and provide the information with the Meter Deferment application.

Where do I send the Backflow Service Application? What is the fee for a new irrigation meter?

Please send backflow/meter applications and fees to:

Charlotte Water


5100 Brookshire Blvd,

Charlotte, NC 28216.

Please contact New Services at (704)336-7600 for any questions regarding fees for water taps and meters.

I have a building project under construction and just had my backflow tested, however, I still have a project hold, did I do something wrong?

You need to contact the backflow inspections department at (704)391-5188 and see if there are additional holds for a backflow inspection.  Inspector needs to ensure the installation of the backflow. Ten days after the backflow inspection the backflow assembly needs to be tested by a Charlotte Water Backflow Approved Tester.

The meter and backflow were installed, and the installer left the meter cover open, so I wanted to know do we close it or is somebody else coming back to close it?

Please call the backflow inspection department for the inspector needs to ensure the installation of the backflow.