How to Calculate Your Sewer Bill

Who's your sewer provider?

We provide billing services for other sewer utilities within our service area. Your sewer provider is listed on your bill. If we aren't your sewer provider, visit your sewer utility's website for rate information, or call us at (843) 727-6800. List of sewer providers

Sewer rates

Learn more about our rate structure and view current and past rate schedules here.

Your sewer bill

Your sewer bill is based on your water use, as most water ends up flowing into the sewer system. Your sewer bill includes:

Minimum Bill + Volume Charge = Sewer Bill

All customers pay the minimum bill, which includes up to 2 Ccf (1,496 gallons) of sewer use. If you use more than 2 Ccf, you'll pay a volume charge. To calculate your sewer bill, you need to know:

  • How much water you used
     This is noted on your bill.    *Sewer customers that don't have metered water service are billed the 2021 non-metered flat rate, which is $62.78 (inside-city) and $86.87 (outside-city) based on 6 Ccf of sewer volume.

    Whether you live inside or outside the City of Charleston
    This affects your minimum bill and volume charge.

Calculate your sewer bill:

  1. Determine your billable sewer consumption

    For single-family residential customers that don't have a separate irrigation meter, your billable sewer use is 95% of your water consumption (multiply water consumption by 0.95). All other customer classes are billed for sewer based on 100% of water use.

    Residential customer used 6 Ccf of water and does not have a separate irrigation meter:  6 Ccf x 0.95 = 5.7 Ccf billable sewer

    Residential customer with a separate irrigation meter who used 8 Ccf of water:   8 Ccf billable sewer

  2. Determine your minimum bill

    If your billable sewer consumption is below Ccf, this is your total sewer bill. If you used more than 2 Ccf, continue to step 3.

       Minimum Bill Amount
    Rates effective Jan. 1, 2023
       Inside City:     $35.00
       Outside City:  $49.40


  3. Determine how much sewer used above the 2 Ccf minimum

    For example, if your billable sewer consumption is 5.7 Ccf, the first 2 Ccf are included in your minimum bill. That means you'll pay a volume charge for the additional 3.7 Ccf.

             5.7 Ccf (total use)  -  2 Ccf (minimum bill) = 3.7 Ccf
  4. Calculate the volume charge

    Find the appropriate unit rate based on whether you live in or outside the City of Charleston, and multiply it by the amount of water you calculated in step 2.

     Sewer Use (Ccf)
     Inside City of Charleston
     Outside City
     Over 2 Ccf$9.53 per Ccf  $14.10 per Ccf
    Rates effective Jan. 1, 2023

    Continuing the example above, if the residential customer lives inside City of Charleston, they would calculate volume charge like this:

    3.7 Ccf x $9.53 = $35.26 (volume charge)

  5. Add the volume charge to the minimum bill

    This is your total sewer bill.

    $35 (minimum bill) + $35.26 (volume charge) = $70.26
    Note: Residential customers who don't have a separate irrigation meter will not be charged more than the maximum sewer charge, which is based on 17.1 Ccf of billable sewer use.

    Maximum Sewer Charge (2023 rates)
    For residential customers without an irrigation meter
    Inside City: $178.90
    Outside City: $262.31