Septic tanks, as the name indicates, are supposed to make the environment hygienic, and not worsen it. It is supposed to dispose of human wastes from toilets without creating any sort of nuisance. Well, if it is constructed properly it does what it is supposed to. Otherwise, it could even create health hazards.
‘Septic tanks’ create health hazards?!! Yes, it can. And, it does. How?
1. When the septic tank is constructed as a single pit instead of chambers:
The three chamber septic tanks constructed with chambers separated with diaphragm walls, clean water comes out from the outlet in the last chamber. This is to be disposed of into a soak pit
2. When the septic tank with single chamber has outlet connected to drains: This will result in stinking waste water and materials being discharged into drains and the drains will breed mosquitoes besides spreading foul smell around
3. In water logged areas, especially during rainy season, the soak pit gets soaked up with surrounding water and the water from soak pit enters the septic tank and may choke up the toilets in the ground floor, creating undesirable scenes
4. A soak pit constructed without filling it with brickbats could result in waste water pooling inside the pit, providing ideal breeding ground for mosquitoes. Mosquito menace will be incredibly high if rodents and other creatures make openings into the pit from the ground surface enabling mosquitoes to enter the tank through the holes they make and lay eggs in the tank.
Due to the above reasons I found it better to go for installing PVC septic tanks in my building projects. They are factory made and therefore scientifically constructed with chambers; besides they do not let their surfaces from being damaged and thus air tight except for the vent cowl, which could be protected with mosquito nets. Thus mosquito menace could be avoided. They have inspection chambers and the water that oozes out of the outlet into the soak pit is clear water. The soak pit could be kept a little down from the outlet of the septic tank so that water from the soak pit does not reverse flow into the tank during waterlogging conditions around. It is easy to install PVC septic tanks.. Just dig out soil and place the tank in the trench. Backfill with soil. Get a plumber and he will connect the 110mm PVC pipe from the tank to the toilet outlet. The vent pipe (with vent cowl) is usually 50mm and it is connected into the tank. A soak pit of required size (say 1mx1mx1m) is made by making a chamber in the ground and filling it with brickbats. the outlet of the septic tank is to discharge the water into the soak pit.
Fill the tank with water before using. That is all.
This image is taken from here.
I made some inquiries and created data to estimate the cost of installing the tank.
I contacted the company that manufactures the tank and they provided certain data. The sizes of tanks are expressed based on number of flushes per day and it is worked out taking 3 flushes / person/ per day. Thus if there are 10 persons a tank with capacity 3×10=30 flushes per day may be used.
You can get various types of tanks being manufactured by the company by clicking here.
I have worked out the cost of installing the tank as follows:
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8
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1
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nos
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Supplying and installing PVC Septic tank (50-60 flushes/day) and connected plumbing works with 110mm PVC pipes 4kg/cm2, door elbow, bends, 50mm 6kg/cm2 vent pipe, vent cowl etc and all other fittings, sundries etc including cost of all materials and labour charges etc complete
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||||
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1
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nos
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Cost of Septic tank
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26500
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E
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26500
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||
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2.5
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m
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110mm Dia PVC pipe 4Kg/cm2
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130
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m
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325
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||
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1
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nos
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Door elbow
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99
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E
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99
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||
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2
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nos
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PVC bend
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108
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E
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216
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||
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3
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m
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PVC vent pipe 50mm for 6Kg/cm2
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38
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E
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114
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||
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1
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nos
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vent cowl
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25
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E
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25
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||
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LS
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LS for Transportation charge
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300
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For sundries
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30.00
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Add 10% C. P on Rs.
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779.00
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77.90
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Total
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27686.90
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E
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Besides there is the cost of making the soak pit too.
