(B) The estimated design flow for any Dwelling must provide for at least two (2) Bedrooms. For multiple or multifamily Dwellings, the design flow consists of the sum of the design flows for each individual unit.
(C) The estimated design flow for Dwellings is based on Table I, which is based on calculating the number of Bedrooms by 150 gallons per day.
Table I
Number of Bedrooms Gallons per Day
2 300
3 450
4 600
5 750
6 900
(D) The design flow for MSTS serving existing Dwellings is determined by the following calculation in conjunction with division (C) of this section.:
Total flow from the ten highest flow Dwellings + (total flow from the remaining Dwellings X 0.45)
(E) For new housing developments, the developer shall determine and restrict the total number of Bedrooms for the development and determine the design flow by multiplying the total number of Bedrooms by 110 gallons per day. If the ultimate development of phased or segmented growth meets or exceeds 10,000 gallons per day, the initial system or systems and all subsequent systems require a state disposal system Permit.
(F) If construction of additional Dwellings or Bedrooms, installation of water-using devices, or other factors likely to increase the flow volumes can be reasonably anticipated, the SSTS must be designed to accommodate the additional capacity as determined by the Department or local unit of government.
(G) Design Sewage flow for Other Establishments are determined by methods in divisions (G)(1) or (2) below:
(1) The design flow of Sewage for MSTS serving Other Establishments is estimated using Table II.
(2) The measured design flow of Sewage for MSTS serving Other Establishments is determined by averaging the measured daily flows for a consecutive seven-day period in which the establishment is at maximum capacity or use.
Table II - Estimated Design Sewage Flow from Other Establishments
Dwelling Units (also see outdoor recreation) | Unit | Design Flow (gallons/day/unit) |
Dwelling Units (also see outdoor recreation) | Unit | Design Flow (gallons/day/unit) |
Hotel or luxury hotel | Guest | 55 |
Square foot | 0.28 | |
Motel | Guest | 38 |
Square foot | 0.33 | |
Rooming house | Resident | 45 |
Add for each non-resident meal | 3.3 | |
Daycare (no meals) | Child | 19 |
Daycare (with meals) | Child | 23 |
Dormitory | Person | 43 |
Labor camp | Person | 18 |
Labor camp, semi permanent | Person | 50 |
Commercial/Industrial | Unit | Design Flow (gallons/day/unit) |
Retail Store | Square foot | 0.13 |
Customer | 3.8 | |
Toilet | 590 | |
Shopping center | Employee | 11.5 |
Square foot | 0.15 | |
Parking space | 2.5 | |
Office | Employees/8-hour shift | 18 |
Square foot | 0.18 | |
Medical office* | Square foot | 1.1 |
Practitioner | 275 | |
Patient | 8 | |
Industrial Building | Employees/8-hour shift | 17.5 |
Employees/8-hour shift with showers | 25 | |
Laundromat | Machine | 635 |
Load | 52.5 | |
Square foot | 2.6 | |
Barber shop | Chair | 68 |
Beauty salon | Station | 285 |
Flea market | Nonfood vendor/space | 15 |
Limited food vender/space | 25 | |
With food vendor/space | 50 | |
Eating and Drinking Establishments | Unit | Design Flow (gallons/day/unit) |
Restaurant (does not include bar or lounge) | Meal without alcoholic drinks | 3.5 |
Meal with alcoholic drinks (open 16 hours or less) | 8 | |
Seat (open 16 hours or less) | 30 | |
Seat (open more than 16 hours) | 50 | |
Seat (open 16 hours or less, single service articles) | 20 | |
Seat (open more than 16 hours, single service articles) | 35- | |
Restaurant - short order | Customer | 7 |
Restaurant - drive-in | Car Space | 30 |
Restaurant - carry out, including caterers | Square foot | 0.5 |
Institution meals | Meal | 5.0 |
Food outlet | Square foot | 0.2 |
Dining hall | Meal | 8.5 |
Coffee shop | Customer | 7 |
Cafeteria | Customer | 2.5 |
Bar or lounge (no meals) | Customer | 4.5 |
Entertainment Establishments | Unit | Design Flow (gallons/day/unit) |
Drive-in theater | Car stall | 5 |
Theater/auditorium | Seat | 4.5 |
Bowling alley | Alley | 185 |
Country club | Member (no meals) | 22 |
Member (with meals and showers) | 118 | |
Member (resident) | 86 | |
Fairground and other similar gatherings | Visitor | 1.5 |
Stadium | Seat | 5 |
Dance hall | Person | 6 |
Health club/gym | Member | 35 |
Outdoor Recreation and Related Lodging Facilities | Unit | Design Flow (gallons/day/unit) |
Campground | Person with hook-up | 36 |
Site with hook-up | 100 | |
Site without hook-up, with central bath | 62 | |
Site to be served by dump station | 14.5 | |
Permanent Manufactured home | Mobile Home | 225 |
Camp, day without meals | Person | 20 |
Camp, day, and night with meals | Person | 45 |
Resort/lodge hotel | Person | 62 |
Cabin, resort | Person | 50 |
Retail resort store | Customer | 4 |
Park or swimming pool | Guest | 10 |
Visitor center | Visitor | 13 |
Transportation | Unit | Design Flow (gallons/day/unit) |
Gas station/convenience store | Customer | 3.5 |
Service station* | Customer | 11 |
Service bay | 50 | |
Toilet | 250 | |
Square foot | 0.25 | |
Car wash* (does not include car wash water) | Square foot | 5 |
Airport, bus station, rail depot | Passenger | 5 |
Square foot | 5 | |
Restroom | 565 | |
Institutional | Unit | Design Flow (gallons/day/unit) |
Hospital* | Bed | 220 |
Mental health hospital* | Bed | 147 |
Prison or jail | Inmate | 140 |
Nursing home, other adult congregate living | Resident | 125 |
Other public institution | Person | 105 |
School (no gym, no cafeteria, and no showers) | Student | 14 |
School (with cafeteria, no gym, and no showers) | Student | 18 |
School (with cafeteria, gym, and showers) | Student | 27.5 |
School (boarding) | Student | 95 |
Church | Seat | 4 |
Add for each meal prepared | ||
Assembly hall | Seat | 4 |
Miscellaneous | Unit | Design Flow (gallons/day/unit) |
Public lavatory | User | 5 |
Public shower | Shower taken | 11 |
* Waste other than Sewage is only allowed to be discharged into the system if the waste is suitable to be discharged to groundwater. | ||
(H) Unless otherwise noted in Table II, the flow values do not include flows generated by employees. A flow value of 15 gallons per employee per eight hour shift must be added to the flow amount for determining the design flow for Other Establishments.
(I) Design flow determination for establishments not listed in Table II shall be determined by the base available information and approved by the Department or by the local unit of government.
(J) The measured flow of Sewage for existing Other Establishments may be used to modify estimated flow values determined in this part if the length and frequency of the measured flow accurately represents the annual average water use, along with the peak weekly and daily water use.
(K) The design flow for MSTS must also include 200 gallons of infiltration and inflow per inch of collection pipe diameter per mile per day with a minimum pipe diameter of two inches to be used for the calculation. Flow values are allowed to be further increased if the system employs treatment devices that are exposed to atmospheric conditions that will infiltrate precipitation. Flow estimates as calculated in this Chapter shall not be relied upon for the design of collection systems.
(L) If concentrations of Biochemical Oxygen Demand, total suspended solids, and oil and grease from the Sewage are expected to be higher than 175 mg/L, 65 mg/L, or 25 mg/L, respectively, an estimated or measured average concentration must be determined and be acceptable to the Department or local unit of government. System design must account for concentrations of these constituents so as to not cause internal system malfunction, such as, but not limited to, clogging of pipes, orifices, treatment devices, or media.