Residential Class 4F & 4 Septic Systems (Guide Only) 
Total Daily Design Flow Rates For Residential Occupancy "Q" (Litres per Day) 
Design Criteria  User Input  Litres/Day 

Bedrooms up to 5  4  2000  
Each bedroom over 5 add 500  0  0  
Each plumbing fixture over 20 add 50  15  0  
Each 10m² (or part therof) of floor area greater then 200 m² up to 400 m² add 100  150  0  
Each 10m² (or part therof) of floor area greater then 400 m² up to 600 m² add 75  150  0  
Each 10m² (or part therof) of floor area greater then 600 m² add 50  150  0 
subtract the lesser of fixture units litres compared to floor area litres  0  
Total Q =  2000 
Septic
Tank Size (minimum size required for this residential septic tank) 
4000 Litres (879.9 Imp Gallons) (1544.5 US Gallons) 


Minimum filter area (if Q is less than 3000 than Q/75 else Q/50)  Q/75=26.7 m² (287 ft²)  
Minimum filter base contact area Q x filter T divided by 850  Q x filterT/850=23 m² (248 ft²)  
Loading Area (mantle) Q divided by mantle T  Q/mantleT=285 m² (3068 ft²) 

Trench Percolation (T=20)  Silty Sands 
Pipe Length Required (min. 40 m) L=Q x Trench T/200  200.0 m (656 ft) 
Septic Tank Minimum Clearance  

Distribution Pipe Minimum Clearance  
(increased clearance by twice the bed height above grade. 2 x 1.0 = 2.0 m (6.56 ft)  

Pipe Requirements  

Filter Bed Requirements  

Final Grading  
 
Wednesday, August 23, 2017 at 03:47:11 