Contents
What is a septic tank? and why we use it?
The tank which Stores a waste water of House or building is called Septic Tank. Septic Tank is installed where there is no proper drainage system. In order store, the Wastage or sewage for 10-30 Days Septic tank is constructed and the same is designed.
This tank is usually installed below 1.5m-1.8m from ground level. Waste water coming from sewer Pipes of the house are connected to Septic tank.
Wastewater flows into the tank at one end and leaves the tank on the other end as shown in the figure. The septic tank is drained out with the help of suck out the outlet. The municipal Department suck out the wastage from Septic tank.
In the early 1990’s, the tank is constructed without bottom slab below the tank. Due to seepage from Septic tank, the waste water is mixed with Fresh Water sump. To avoid this, the septic tank is cased up with the bottom slab.
All waste water from the bath, toilet, kitchen flows into the tank. Heavy Solids in waste water is settled at bottom of the tank. Due to the presence of anaerobic bacteria in waste water Heavy solids are reduced to sludge and gases. Generally, if the density of solids which is more than the water is settled at the bottom of tank, if density of solids which is less than the water floats. The settled Solids is called as Sludge and floating solids is called as scum.
Septic Tank Maintenance:-
Remove the sludge when it reaches up to the height of 3″ below the suck out the pipe. Due to the presence of Waste gases, there might be a chance of smell coming out from the pit. Periodic effluent is added to the septic tank to avoid the smell.
The design of Septic Tank:-
Septic tank Consists of Top Slab, Bottom Slab with PCC Bed, Shear walls around the tank and a top cover (Opening) to check the level of Waste water. Below are the septic tank design calculations.
How to design Septic System?
For clear understanding here we designing a septic tank for 8 people in a house which get filled in 10 Days.
The average waste generated from each human / Day including kitchen waste = 95 to 150 liters/Day.
The average waste generated from each human includes
- Bathing & toilet = 85 litres/day
- Cooking = 1 litres/day
- Cleaning house = 2 liters/day
- Washing utensils & clothes = 6 liters/day
- Others = 1 litres/day
The values may change as per location and atmospheric conditions.
Calculation:-
Total Members in house = 8 (Assume)
Total Waste Generated by House = 8 x 130 = 1040 lts/Day [Considering 130Lts]
The Total waste generated by house in 10 days = 10 x 1040 = 10,400lts
Remember , 1m3 = 1000 litres (Standard)
So, For 10,400lts = 10.4 m3
How to find Septic tank Size:
In order to calculate the Septic tank size know about the standard length and width ratio of Septic tank.
The length and width ratio of Septic tank is 4:1 or 2:1
The depth or height of Septic tank is in between 1.5m- 1.8m
So the area of Septic tank = 10.4/1.8 = 5.78m2
Considering Length and width ratio = 4:1
Length of Septic tank = (4/5) x 5.78 = 4.62m
Breadth or Width of Septic tank = (1/5) x 5.78 = 1.15m
(Approx 10.4 m3)
Length, Breadth & Depth of Septic tank = 4.6m x 1.15m x 1.8m
Automatic Calculator For Septic Tank Size Calculation:-
You can also read:-
- 10 Types of footings or foundations which we adopt in Construction
- 16 Different types of slabs in construction
- Different types of Columns in construction
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The best civil engineering site, I like this page
am constricting a house . the septic tank length is 7’3
breadth is 6’10
depth 5’4 . How much capacity the septic tank carries in liters pls help me to know
I want post related to combined gradation of aggregates .
soon it is updated stay connected with us
Thank you so much sir
Very helpful updates for daily routine works.
Thank you
Sirjee
thanks for ur comments
Dear Vamsi ,
I donot know how to thank you. My first initiation into this subject was way back in 1984. At that I was officer in charge of sanctioning housing loans to st.aff members. I was expected release installments based on stage wise construction. The bank will finnace 80% of the project cost. 20 % has to be borne by the people. Hence therewas tendency to inflate project cost. As many bank officials are ignorant of civil costing and estimation bankers were taken for a ride. I was in dilemma as how I overcome this knowledge gap. Than I found one book written by Retired Superintendent Engineer with 30 years of working experience in R& B. It has costed Rs100/ which was a big amount in those days. That put me good condition to face the challenges of my job. In those days many people were not engaging qualified engineers. Their dependence on unqualified Maistry who have taken people for ride compromising on the safety of the structure. In my reading coupled with keen observation and questioning helped not me and my staff members to know how they are cheated by Contractor. In local Civil Engineers have appreciated by observations and supported my views. Now I am learning about concrete structures in lucid manner so that I guide needy people and support my self when start constructing my little home with what I received on my retirement. Very nice of you. God bless you with long and happy life. Please the people. I will be with you.
please write some thing practical on soil testing etc.
coming soon.!!!
very informative.
i like to know , what next after designing septic tank for its capacity. How about the reinforcement details.
Because then and then only estimation and costing will add advantage to whole.
Regards
Santoshkumar shrilele/9967447270
Hi thanks for ur comment currently im writing an article on BBs for slab soon i gonna add BBS for septic tank, water sump, beams etc. Stay connected with us
how can I take cone shape chamber bricks quantity?
as there different methods for this i prefer you to cut the cone it becomes sector and use sector formula to find the area of the cone
Hello sir all the information reagarding the spetic tank is fine i want to know why the baffle wall is constructed in the septic tank what is the usage and how should we provide either along the horizontal side or vertical side of the septic tank clearify me sir…..
morning please do a piece on boqs
sure i ll add in my list. Share some info on [email protected] on which u need BOQ
What kind of conderation to put in place at a water lodge area. Also how can someone combine septic tank and soakaway together in a dry land area.
I find this post both helpful and
informative. Thank you for your time and effort to help others.
Length 7’3
breadth 6’10
Depth 5’4
What will be my septic tank capacity how much liters it will carry