Sewer Rates

Who's your sewer provider?
Charleston Water System only provides sewer service to areas within the City of Charleston, unincorporated areas in West Ashley, parts of Johns Island, and the Cainhoy peninsula.

For CWS water customers outside of these areas, public sewer service is provided by one of the following utilities:

Charleston Water System is the billing agent for some of these sewer providers (you'll see this noted on your bill), but we do not set rates or manage the sewer infrastructure for these agencies.

Charleston Water System's Sewer Rates
Sewer rates are based on water consumption. This is because the majority of water you use goes down drains and toilets and ends up in the sewer system. Charleston Water System charges a minimum monthly sewer bill for the first 2 Ccf of wastewater volume and a specific rate for each additional Ccf (748 gal).

For single-family residential customers that do not have an irrigation meter, sewer charges are based on 95% of metered water usage. Residential sewer customers who receive their water service from St. Johns Water Company are billed for sewer based on 100% of water usage.

For multi-family residential customers, single-family residential customers with an irrigation meter, and commercial customers, sewer charges are based on 100% of metered water usage.

View current rate schedule | View archived rate schedules

Monthly Minimum Charge
Effective 1/1/2016

Inside City  Outside City 
 $29.00  $41.00


Volume Charge
Billable sewer use is calculated at 100% of metered water use for commercial customers, multi-family residential customers, and single-family residential customers that have a separate irrigation meter. Single family residential customers that do not have a separate irrigation meter are billed for sewer based on 95% of metered water use.

The first 2 Ccf of sewer volume is included in the minimum bill. Usage above that is billed per Ccf.

Volume Charge for Sewer Use Above 2 Ccf
Effective 1/1/2016
Sewer Use (Ccf)*
Based on metered water use
 Inside City Rate  Outside City Rate
 Over 2 Ccf  $7.31 per Ccf  $9.83 per Ccf
Max charge for single family residential customers that do not have an irrigation meter (17.1 Ccf)  $139.38  $189.43
 Non-metered flat rate (6 Ccf)  $56.05  $77.37












*Notes:


  1. Volume billed for in cubic feet (CF) for all fractional usage under a hundred cubic feet (Ccf).
  2. Sewer charges for single-family residential customers that do not have a separate irrigation meter are based on 95% of water use. For example, 7 Ccf of water use would be billed for 6.65 Ccf of sewer use (7 x 0.95 = 6.65).
  3. Sewer charges for residential customers that have separate irrigation meter and all other customer classes are based on 100% of metered water usage.
  4. Sewer charges for non-residential or multi-family accounts are based on 100% of water use.
  5. CWS residential sewer customers who are provided retail water service by St. Johns Water Company are billed for wastewater based on 100% of water volume.
  6. Sewer cap - Single family residential customers without an irrigation meter will be charged no more than the maximum rate for wastewater service. The maximum charge is based on 18 Ccf of water usage (17.1 Ccf wastewater volume).
Non-metered flat rate
Charleston Water System sewer customers who do not have metered water service are billed the non-metered flat rate, which is based on 6 Ccf of sewer volume.

Irrigation Meters
Charleston Water System offers separate irrigation meters for customers who use a high volume of water for irrigation purposes. Irrigation meters are not charged for sewer. Learn more about irrigation meters

Purchased Treatment
In addition to retail sewer service, Charleston Water System provides treatment services to several municipalities in the Greater Charleston area, including the James Island Public Service District and the Towns of Hollywood, Ravenel, and Meggett.

This means that wastewater generated from these areas flows through a master meter and is treated at Charleston Water System’s plant, but Charleston Water System does not provide direct service to customers in those areas.