N.J. Admin. Code § 7:9A-7.4 - Volume of sanitary sewage

(a) Each component of the individual subsurface sewage disposal system shall be designed and constructed to adequately treat and dispose of the expected volume of sanitary sewage to be discharged from the premises to be served. The expected volume of sanitary sewage from single residential occupancy activities shall be determined based on the criteria set forth in (b) below. The expected volume of sanitary sewage from establishments which have activities other than single residential occupancy shall be determined based on the criteria set forth in (c) below. The total expected volume is based on a maximum use day and shall be calculated by adding the daily volume of sanitary sewage associated with all activities proposed and planned in accordance with municipal subdivision or site plan approvals.
(b) The criteria for estimating the volume of sanitary sewage from single residential occupancy activities shall be as follows:
1. The daily volume for each bedroom or dwelling unit shall be:

i. Volume, first bedroom 200 gallons per day ("gal/day");
ii. Volume, each additional bedroom 150 gal/day;
iii. Minimum volume per dwelling unit 350 gal/day; and
iv. Minimum volume per apartment 350 gal/day.
2. The administrative authority may approve the reduction of the daily design volume for a one-bedroom age-restricted unit or one-bedroom mobile home dwelling units less than 500 square feet in size to 200 gallons per day.
(c) The volume of sanitary sewage from establishments which have activities other than single residential occupancy shall be based upon the types of activities that are expected to occur that will generate sanitary sewage, the size of the facility and the maximum expected number of persons that may be served during any single day of operation. The total expected volume shall be estimated for each activity generating sanitary sewage by multiplying the number of gallons per unit per day by the maximum anticipated number of units as identified in Tables 7.4(a) and 7.4(b) below. Those tables identify the appropriate units to be used based upon each activity. Those tables shall be used as follows:
1. Identify the primary activity for the facility in Table 7.4(a) below, in consideration of those activities defined at 7:9A-2.1, and calculate the primary activity volume. If more than one primary activity is proposed, each primary activity shall be calculated separately and then added together to calculate the total primary activity volume;
2. Identify each additional source of sanitary sewage proposed for the facility. If an activity is specifically excluded by a footnote to the primary activity(ies) identified in (c)1 above, those additional sources do not need to be added to the total volume for those primary activity areas. If those additional sources of sanitary wastewater are not specifically excluded, calculate the volume for each additional source of sanitary wastewater and add it to the total volume; and
3. If a primary activity in Table 7.4(a) below, is not identified, the administrative authority may allow for the applicant to use appropriate additional source(s) of sanitary sewage activities for the proposed facility to determine the total design volume calculation. If there is question regarding the design volume calculation, the administrative authority shall direct the applicant to apply for a treatment works approval pursuant to 7:9A-3.9 for the Department to determine the appropriate volume.
(d) The criteria listed in Tables 7.4(a) and 7.4(b) below reflect the average amount of sanitary sewage expected to be generated by the listed activities and shall be used to calculate the estimated volume of sanitary sewage. If an administrative authority determines that a proposed type of activity(ies) is not listed in the tables below or is not appropriately represented by the tables below, the administrative authority shall direct the applicant to obtain a treatment works approval for the total expected volume.
(e) When facilities with activities generating sanitary sewage use portable toilets, temporary restrooms or holding tanks on a regular basis, the total design volume from all activities shall be used to determine the total volume for the facility. The total design volume from these facilities shall be calculated as prescribed in (c) above. The use of portable toilets, temporary restrooms or holding tanks for sanitary sewage from activities at any facility shall not be used to reduce the total design volume. The only exception to this requirement is for sanitary sewage volume associated with the use of portable toilets, temporary restrooms or holding tanks during the construction of a realty improvement.
(f) Facilities incorporating commercial food service, golf course, country club, prison, hospital, funeral home, hotel, campgrounds and laboratory related activities shall apply for a treatment works approval to determine total expected volume, if an application proposes flows no greater than 2,000 gallons per day. Hospitals include, but are not limited to, medical or psychiatric institutions with the capacity to accommodate patients overnight.

Table 7.4(a)
Primary Design Criteria
Primary Daily Units Footnotes
Activity Volume
Commercial Use 15 Employee or 1, 2, 3
0.125 Gross Square Footage
(whichever results in
greater volume)
General Assembly 3 Seat/Person 1, 2, 4
Congregate living 130 50 Sleeping unit Bed 1, 5
(whichever results in
greater volume)
Warehouse 15 5 Maximum Employees; and 1, 2, 6
Delivery/Field Personnel
Vehicle service 125 Fueling Position; and 1, 2, 7
10 Vehicle served in
service bays
Education/Child Go to Table Maximum number of 1
care 7.4(b) students (includes
teachers and other

Table 7.4(b)
Additional Design Criteria
Additional Daily Units Footnotes
Source of Volume
Sanitary (gallons)
Private Access 10 Person Served
Public Access 5 Person Served
Showers 5 Person Served 6, 9
Food Service 5 Person Served; or 1, 7, 10
35 Seat (whichever
results in greater
Laundry Increase 1, 11
expected daily
volume from other
activities by 50
percent or
550 Machine
Sink Station 120 Sink 2
Minimum Criteria 350 12


1. Total expected volume shall be calculated using a maximum service day; therefore, the use of this criterion does not preclude using criteria for every other proposed or existing activity for the facility.
2. The volume generated by public or private access restroom facilities is not required in addition to the referenced activity criteria. Design criteria from food service are not required for facilities with employee lunch rooms which limit food preparation to employees preparing their own individual meals.
3. Kennels and veterinary offices with kennels shall include an additional 10 gallons per animal that could be kenneled on a maximum service day.
4. Projected flow shall be calculated based upon a design criteria of three gallons per seat (including both fixed and non-fixed seating) during maximum occupancy.
5. Estimated volume shall be calculated based on the number of sleeping units or beds, whichever results in a greater number plus any additional volume sanitary sewage generated from employee restrooms, shower, laundry and food preparation activities if present.
6. Design criteria for warehouse activities is 15 gallons per day per employee per eight hour shift and is based upon the maximum number of employees working an eight hour shift a day. A design criterion of five gallons per day shall be used for part time employees and delivery personnel. For example, a warehouse that operates with three shifts proposes 10 employees on one shift but only five employees for the other two shifts must calculate based upon the maximum use and therefore provide volume for three 10-employee shifts or 450 gallons plus any additional flows for delivery personnel or part time employees that might have access to restrooms plus any additional volumes associated with additional sources of sanitary sewage applicable in Table 7.4(b).
7. A design criterion of 125 gallons per day per gasoline fueling position and 10 gallons per day per motorized vehicle served in service bays on a maximum use day shall be used for motorized vehicle service activity.
8. Additional sources of sanitary sewage shall be included in the cumulative daily volume when applicable.
9. The design criteria for showers shall be used when shower facilities are available; this includes employee showers at any factory, warehouse, industrial building or other place of business (other than emergency shower facilities) as well as showers for patrons at swimming pools, clubs or schools.
10. The number of seats must be calculated using the maximum number of indoor and outdoor table and counter seats that may be available on a maximum use day.
11. Public, centralized or commercial laundry activities shall use a design criterion of 550 gallons per day per machine. For any other realty improvement, design criteria for realty improvements that include laundry facilities must increase design volume by 50 percent for each unit containing those facilities.
12. The minimum design volume for any system is 350 gallons per day, other than a single system serving a single dwelling unit identified in 7:9A-7.4(b). This criterion shall be used when any calculated criteria from this table results in an estimated volume of sanitary sewage less than 350 gallons per day.


N.J. Admin. Code § 7:9A-7.4
Amended by R.1994 d.469, effective 9/19/1994.
See: 26 N.J.R. 2715(a), 26 N.J.R. 3829(a).
Amended by R.2012 d.066, effective 4/2/2012.
See: 43 N.J.R. 478(a), 44 N.J.R. 1047(a).
Rewrote (a) through (d); and added (e) and (f).

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