(a)  This Rule shall be used to determine wastewater flow rates for all systems governed by this Subchapter unless alternate criteria are provided by a program-specific rule or for flow used for the purposes of 15A NCAC 02H .0105. Higher flow rates shall be required where usage and occupancy are atypical, including those in Paragraph (e) of this Rule. Wastewater flow calculations shall take hours of operation and anticipated maximum occupancies and usage into account when calculating peak flows for design.

(b)  In determining the volume of sewage from dwelling units, the flow rate shall be 120 gallons per day per bedroom. The minimum volume of sewage from each dwelling unit shall be 240 gallons per day and each additional bedroom above two bedrooms shall increase the volume by 120 gallons per day. Each bedroom or any other room or addition that can function as a bedroom shall be considered a bedroom for design purposes. When the occupancy of a dwelling unit exceeds two persons per bedroom, the volume of sewage shall be determined by the maximum occupancy at a rate of 60 gallons per person per day.

(c)  The following table shall be used to determine the minimum allowable design daily flow of wastewater facilities. Design flow rates for establishments not identified below shall be determined using available flow data, water‑using fixtures, occupancy or operation patterns, and other measured data.


Type of Establishments                                                                                          Daily Flow For Design

Barber and beauty shops

    Barber Shops                                                                                                        50 gal/chair

    Beauty Shops                                                                                                       125 gal/booth or bowl

Businesses, offices and factories

    General business and office facilities                                                               25 gal/employee/shift

    Factories, excluding industrial waste                                                              25 gal/employee/shift

    Factories or businesses with showers or food preparation                          35 gal/employee/shift

    Warehouse                                                                                                            100 gal/loading bay

    Warehouse – self storage (not including caretaker residence)                    1 gal/unit


    Churches without kitchens, day care or camps                                             3 gal/seat

    Churches with kitchen                                                                                        5 gal/seat

    Churches providing day care or camps                                                           25 gal/person (child & employee)

Fire, rescue and emergency response facilities

    Fire or rescue stations without on site staff                                                   25 gal/person

    Fire or rescue stations with on-site staff                                                         50 gal/person/shift

Food and drink facilities

    Banquet, dining hall                                                                                            30 gal/seat

    Bars, cocktail lounges                                                                                         20 gal/seat

    Caterers                                                                                                                 50 gal/100 sq ft floor space

    Restaurant, full Service                                                                                      40 gal/seat

    Restaurant, single service articles                                                                     20 gal/seat

    Restaurant, drive-in                                                                                             50 gal/car space

    Restaurant, carry out only                                                                                  50 gal/100 sq ft floor space

    Institutions, dining halls                                                                                     5 gal/meal

    Deli                                                                                                                         40 gal/100 sq ft floor space

    Bakery                                                                                                                   10 gal/100 sq ft floor space

    Meat department, butcher shop or fish market                                              75 gal/100 sq ft floor space

    Specialty food stand or kiosk                                                                            50 gal/100 sq ft floor space

Hotels and Motels

    Hotels, motels and bed & breakfast facilities,

      without in-room cooking facilities                                                                 120 gal/room

    Hotels and motels, with in-room cooking facilities                                       175 gal/room

    Resort hotels                                                                                                         200 gal/room

    Cottages, cabins                                                                                                   200 gal/unit

Self service laundry facilities                                                                                                500 gal/machine

Medical, dental, veterinary facilities

    Medical or dental offices                                                                                   250 gal/practitioner/shift

    Veterinary offices (not including boarding)                                                   250 gal/practitioner/shift

    Veterinary hospitals, kennels, animal boarding facilities                             20 gal/pen, cage, kennel or stall

    Hospitals, medical                                                                                               300 gal/bed

    Hospitals, mental                                                                                                150 gal/bed

    Convalescent, nursing, rest homes without laundry facilities                      60 gal/bed

    Convalescent, nursing, rest homes with laundry facilities                           120 gal/bed

    Residential care facilities                                                                                   60 gal/person

Parks, recreation, camp grounds, R-V parks and other outdoor activity facilities

    Campgrounds with comfort station, without

      water or sewer hookups                                                                                   75 gal/campsite

    Campgrounds with water and sewer hookups                                               100 gal/campsite

    Campground dump station facility                                                                  50 gal/space

    Construction, hunting or work camps with flush toilets                               60 gal/person

    Construction, hunting or work camps with chemical or

      portable toilets                                                                                                   40 gal/person

    Parks with restroom facilities                                                                            250 gal/plumbing fixture

    Summer camps without food preparation or laundry facilities                   30 gal/person

    Summer camps with food preparation and laundry facilities                      60 gal/person

    Swimming pools, bathhouses and spas                                                          10 gal/person

Public access restrooms                                                                                         325 gal/plumbing fixture

Schools, preschools and day care

    Day care and preschool facilities                                                                      25 gal/person (child & employee)

    Schools with cafeteria, gym and showers                                                       15 gal/student

    Schools with cafeteria                                                                                        12 gal/student

    Schools without cafeteria, gym or showers                                                    10 gal/student

    Boarding schools                                                                                                 60 gal/person (student & employee)

Service stations, car wash facilities

    Service stations, gas stations                                                                             250 gal/plumbing fixture

    Car wash facilities                                                                                               1200 gal/bay

Sports centers

    Bowling center                                                                                                     50 gal/lane

    Fitness, exercise, karate or dance center                                                         50 gal/100 sq ft

    Tennis, racquet ball                                                                                             50 gal/court

    Gymnasium                                                                                                          50 gal/100 sq ft

    Golf course with only minimal food service                                                  250 gal/plumbing fixture

    Country clubs                                                                                                       60 gal/member or patron

    Mini golf, putt-putt                                                                                             250 gal/plumbing fixture

    Go-kart, motocross                                                                                             250 gal/plumbing fixture

    Batting cages, driving ranges                                                                            250 gal/plumbing fixture

    Marinas without bathhouse                                                                               10 gal/slip

    Marinas with bathhouse                                                                                    30 gal/slip

    Video game arcades, pool halls                                                                        250 gal/plumbing fixture

Stadiums, auditoriums, theaters, community centers                                       5 gal/seat

Stores, shopping centers, malls and flea markets

    Auto, boat, recreational vehicle dealerships/showrooms

      with restrooms                                                                                                   125 gal/plumbing fixture

    Convenience stores, with food preparation                                                    60 gal/100 sq ft

    Convenience stores, without food preparation                                              250 gal/plumbing fixture

    Flea markets                                                                                                         30 gal/stall

    Shopping centers and malls with food service                                               130 gal/1000 sq ft

    Stores and shopping centers without food service                                         100 gal/1000 sq ft

Transportation terminals – air, bus, train, ferry, port and dock                      5 gal/passenger


(d)  Design daily flow rates for proposed non-residential developments where the types of use and occupancy are not known shall be designed for a minimum of 880 gallons per acre, or the applicant shall specify an anticipated flow based upon anticipated or potential uses.

(e)  Design daily flow rates for residential property on barrier islands and similar communities located south or east of the Atlantic Intracoastal Waterway and used as vacation rental as defined in G.S. 42A-4 shall be 120 gallons per day per habitable room. Habitable room shall mean a room or enclosed floor space used or intended to be used for living or sleeping, excluding kitchens and dining areas, bathrooms, shower rooms, water closet compartments, laundries, pantries, foyers, connecting corridors, closets, and storage spaces.

(f)  An adjusted daily sewage flow design rate shall be granted for permitted but not yet tributary connections and future connections tributary to the system upon showing that the capacity of a sewage system is adequate to meet actual daily wastewater flows from a facility included in Paragraph (b) or (c) of this Rule without causing flow violations at the receiving wastewater treatment plant or capacity-related sanitary sewer overflows within the collection system as follows:

(1)           Documented, representative data from that facility or a comparable facility shall be submitted by an authorized signing official in accordance with Rule .0106 of this Section to the Division for all flow reduction requests, as follows:

(A)          dates of flow meter calibrations during the time frame evaluated and indication if any adjustments were necessary;

(B)          a breakdown of the type of connections (e.g. two bedroom units, three bedroom units) and number of customers for each month of submitted data as applicable. Identification of any non-residential connections including subdivision clubhouses and pools, restaurants, schools, churches and businesses. For each non-residential connection, information identified in Paragraph (c) of this Rule (e.g. 200 seat church, 40 seat restaurant, 35 person pool bathhouse);

(C)          a letter of agreement from the owner or an official, meeting the criteria of Rule .0106 of this Section, of the receiving collection system or treatment works accepting the wastewater and agreeing with the adjusted design rate;

(D)          age of the collection system;

(E)           analysis of inflow and infiltration within the collection system or receiving treatment plant, as applicable;

(F)           if a dedicated wastewater treatment plant serves the specific area and is representative of the residential wastewater usage, at least the 12 most recent consecutive monthly average wastewater flow readings and the daily total wastewater flow readings for the highest average wastewater flow month per customers, as reported to the Division;

(G)          if daily data from a wastewater treatment plant cannot be used or is not representative of the project area: 12 months worth of monthly average wastewater flows from the receiving treatment plant shall be evaluated to determine the peak sewage month. Daily wastewater flows shall then be taken from a flow meter installed at the most downstream point of the collection area for the peak month selected that is representative of the project area. Justification for the selected placement of the flow meter shall also be provided; and

(H)          an estimated design daily sewage flow rate shall be determined by calculating the numerical average of the top three daily readings for the highest average flow month. The calculations shall also account for seasonal variations, excessive inflow and infiltration, age and suspected meter reading and recording errors.

(2)           The Division shall evaluate all data submitted but shall also consider other factors in granting, with or without adjustment, or denying a flow reduction request including: applicable weather conditions during the data period (i.e. rainy or drought), other historical monitoring data for the particular facility or other similar facilities available to the Division, the general accuracy of monitoring reports and flow meter readings, and facility usage, such as whether the facility is in a resort area.

(3)           Flow increases shall be required if the calculations required by Subparagraph (f)(1) of this Rule yield design flows higher than that specified in Paragraphs (b) or (c) of this Rule.

(4)           The permittee shall retain the letter of any approved adjusted daily design flow rate for the life of the facility and shall transfer such letter to a future permittee.


History Note:        Authority G.S. 143‑215.1; 143‑215.3(a)(1);

Eff. September 1, 2006;

Readopted Eff. September 1, 2018.