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Frequent Overflow of Septic Tank / Soak Pits: Remedy?

We are the occupants of a 14 member flatwherein we have one main septic tank and 3 nos of soak pits.
The sizes are respectively: -

septic tank: 12ftx12ftx12ft (approximate dimensions),

Soak Pits: 4ft dia x 12ft ht - 2 nos. 3ft dia x 12ft - 1 no. (for bathroom & washing machine waste water).

We find the soak pits overflowing frequently and needs removal of waste water by 4 to 5 lorries atleast every 2 months.

What would an ideal remedy be for the situation ?

The ground floor is car park only. and the ground level is 4 to 5 ft from the road level

Thanking you,


+91 8056190546



1. Septic Tank overflow remedy?

A few suggestions as follows:

1.Check for clogged drains

2.There may be too much water flowing into the system

3.Reduce water flow by installing low flush toilets

4.Take shorter showers to conserve water

5.Avoid dumping solids into the drain leading to the septic tank.

6 Avoid putting detergents, paints, solvents and too much bleach into the drain.The chemicals will kill the healthy, good bacteria and prevent decomposition of the process in the septic tank.

7. Try to decompose food outside and avoid dumping it straight into the drain as food takes longer time to decompose.

8. Try to assess the design of the septic tank with the help of a professional for its optimum size as an undersized septic tank is likely to overflow.

2. Dear Raghavan, Suggest best

Dear Raghavan,

Suggest best option is really for all flats to use urine diverting compost (or dehydrating) toilets see, and for careful use of water for all other purposes.  I have been using such a toilet in a second floor apartment for many years. Collect and reuse waste water (especially handwashing water, laundry rinsing water etc) first within the flats and on balcony and roof top for ornamental and vegetable plants, small shrubs, creepers and climbers.  Washing machine water can be used for flushing the toilet.  Try to divert most benign water to water-loving plants in the garden (try to maximise plants even if you have very little space).  If possible plant around the soak pits with thirsty species.
It may also be that the soak pits are old and have become clogged, so cleaning them out and digging deeper if that is permissable and possible or adding new ones. 
Try to reduce your water consumption and try to reuse it as much as possible.  When water is so precious it is shocking to use tap water for watering your plants and for flushing the toilet.
Have a look at 'Ecological Solutions to Flush Toilet Failures' from EcoSolutions (Rs180 Hindi, Rs300 English inclusive of postage)

Paul Calvert

3. Dear Member, We note that

Dear Member,
We note that considerable efforts are being made to pump out / decant waste water in tankers for discharge outside.
If you desire to process say 2000 lits per day, i.e the water coming out as o/ flow from the last soak-pit
and use the same for recycling purposes for secondary purposes, say for flushing, or for complex greens…...lawns, trees, roof-/ terrace gardens, and other uses..
If you consider to install the wwt waste water treatment plant…….then we can suggest methods for the same…..or some basic details are available in the Arghyam web site…..
pl do pruse…...the same..
Do you carry out rain wter harvesting...
Where is your area..??
With well wishes..
Er. Ajit Seshadri
The Vigyan Vijay Foundation,
New Delhi

4. Dear Member, The soak pits

Dear Member,

The soak pits are exhausted, they need some fresh air! And some cousins to help during the breaks and share the loads!!

Trouble free flushings!!
Asit Nema
Foundation for Greentech Environmental Systems
New Delhi

5. Septic tank over flow


Septic Tanks/ Soak pit, has a percolation capacity and beyond that it will not absorb waste which also has OIL and Grease. You need to add Bio products to add to the system to degrade waste and Oil and Grease and starts breathing again. This bacteria will start degrading waste with the existing bacteria in the waste.

Easy and practical solution.

WIth Regards
Hiren Pancholi

6. Frequent overflow of Septic tank - Remedy

The title seems to be wrong as the actual complaint is not one of overflow of septic tank but of the soak pits. Not noting this, several people have commented on septic tanks. The problem is not with the septic tank, hence eco-san toilets cannot solve the problem. Besides, while Paul's work on eco-san toilets is going to result in a fundamental revolution in the field of sanitation in rural India, the problem is that people in towns and semi-urban areas will not opt for eco-san toilets.

Oil and grease do not figure in water used for bathing and washing of clothes.

The basic facts are: The septic tank is actually over sized for the complex and should not give any problem. As for the overflow of soak pits, this is bound to happen whether the pits are old or only a few days old as a mere soak pit cannot process the grey water. If the complex can spare about 2.5 sq ft of soil space per occupant in the garden which receives moderate amount of sunlight, then I can suggest a simple natural process to clean the used water. The soak pits, if they are supported by cement rings, they can be used for storing the cleansed water. My method does not need any chemicals or power or human intervention and has been working in many apartment complexes in Chennai.

Please send me details of the number of flats and total number of occupants in them.

Indukanth Ragade (

7. Septic and soak pit system needs to be revitalised

Dear Mr. Raghavan,

The septic and soak pit system needs to be revitalised. Consider addition of effective bio-cultures that would degrade the excess waste and Oil & grease. Products are available that while sanitising your house arranges to keep your septic system healthy.

Please call for further assistance at 9910170604.


Chandan Mohanty
Technical Advisor
Amrit Clean Water Technologies, Gurgaon

8. Biological treatment for septic tanks

Dear Mr. Raghavan,

We offer biological treatment for septic tanks to enable recycling of waste water after treatment to be used for horticulture. Your soak pit is overflowing as it must have exceeded the percolation capacity due to sludge and grease deposits.

Our microbial solutions when inoculated daily, restore the clogged and choked soak pits and also enable you to reuse the treated water into horticulture, thereby reducing your fresh water demand.

Kindly contact us for further information.

Kush Agarwal
Ecologic Waste Solutions +91-9899823242

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