• In Bangalore it is now mandatory for all complexes with 20 or more flats to set up STP within 3 months
  • Big Relief to Bangalore Apartment Owners- MoEF dilutes Discharge standards on 13-10-2017 to make it easy for STP owners
  • Micro STPs for 20 to 30 Apartments- Faster delivery- Prices start at 5.0 lakhs
  • BBMP issues guidelines on setting up STP in apartments in Bangalore. Details in this website
  • Indus launches 'Zero Discharge Sewage Treatment Plants' & Instant Sewage Treatment Plants 'e-STP'
  • Effluent Treatment Plants for Restaurant, Car Wash & Diary Industry
  • We have launched 'Zero Discharge Sewage Treatment Plant' for 100% recycle of Sewage
  • Channel Associates wanted in All State Capitals

High Quality low cost ETP solutions

Frequently Asked Questions


Septic Tanks
What is the difference between a septic tank, cess pit and a sewage treatment plant? There are three common types of treatment system in use.
Cesspits or Cesspools These are simply a holding tank which must be emptied by tanker on a regular basis. There is no treatment what-so-ever in this. They are large structures, unsuitable for domestic use due to operating costs and they are the least favoured option under present regulations.
Septic tanks ex. GEST Septic Tank provides minimum treatment. Treated water must be discharged to a soakaway only. These are generally only used for smaller domestic developments / hand are nowadays less acceptable to the planners.
Biological Treatment Plants ex. GEPSTP / Custom Designed Plants Provide a much higher level of treatment than septic tanks and may discharge treated water to a water course, provided a Consent to Discharge is in place. Treated water may be suitable for irrigation or other re-use. Modern packaged plants are the officially preferred option at present.
My septic tank / treatment plant is generating foul smell. Why is this happening? Most common reason is incorrect venting arrangement and / or improper plant operation. If it is a septic tank, the tank and drain pipes have to be sealed and vent pipe has to be provided at the correct location. It is important to de-sludge septic tank at right intervals. If it is a biological aeration plant, it has to be operated properly as per manufacturer’s guidance.
What distance from the property does the plant need to be? Septic tank must be located as far as practically possible from the home. Advisable to maintain at least 15 meters distance.
What is the quality of effluent from these plants? All Indus Sewage Treatment Plants (GEPSTP & Custom Designed) are designed to achieve the minimum industry requirement of 30:50:20 mg/l (BOD:SS:NH4-N respectively). Often the performance will be far better than the minimum specified by the environmental regulatory agencies.
What is "Consent to Discharge"? It is a legal document / No objection certificate issued by your local environmental regulatory agency. In India, individual homes are NOT required to get a CONSENT / NOC. Each authority may lay down specific measurable parameters which you will have to satisfy to enable you to discharge the treated sewage effluent from your premises into a watercourse, soakaway or sub irrigation system. In some areas ‘Consent to Discharge’ is not required. Check with your local regulatory authority.
Why do I have to have "Consent to Discharge"? In England and Wales ‘Consent to Discharge’ is a legal requirement under the Water Resources Act 1991. (Schedule 10) (As amended by the Environment Act 1995). However legislation and interpretation of the legislation alters from area to area. In some areas ‘Consent to Discharge’ is not required. Always consult the appropriate regulatory authority.
How long does it take to get "Consent to Discharge"? It can take up to 4 months. Indus Team will assist you through the formalities when a GEPSTP is installed.

General / Others

What is sludge? Sewage sludge is produced from the treatment of wastewater and consists of two basic forms — primary sludge (large solids that go down the toilet and kitchen sinks) and secondary sludge (bacteria that remove the dissolved contaminants from the wastewater). These are combined in the shaft and dewatered together excluding the screenings.

Sludge must be treated and disposed of in a way that makes sure the bacteria and other contaminants cannot impact the environment or human health. Sludge may be treated using a number of processes, and it may be disposed of at landfill, which is designed so the contaminants don’t leach back into the environment.
Additional treatment, such as digesting in buried conditions in the disposal trenches or composting, can allow the sludge to be used as a cover material at a landfill. The sludge in Dawson City will be dewatered and partially digested at the plant. Then it will be taken to the landfill to finish the process of digestion and drying.
How much does a GEPSTP cost to run? The operating cost is dependent on the plant capacity. Look at the plant specifications to understand the energy consumption.
Our house is a holiday home, what happens if I turn the tank off ? You can turn the electricity off and the bacteria will take about 1 week to die. Similarly when you return it'll take about 1 week to create new bacteria in the GEPSTP. However, as mentioned above the annual cost is quite low so it may be worth considering keeping the tank running during periods when the property is not occupied.
What happens if there is a power cut? The GEPSTP will happily go for 2-3 days and over 1 week before all the bacteria are dead. So as long as there isn't a long term issue with the power supply then there shouldn't be a problem.
How long would it take for a tank to be fully operational with bacteria? Once the tank is operational it takes approximately 20 days for it to work at full capacity and for all the bacteria to be present.
How clean is the grey water that exits the GEPSTP? The grey water out of the GEPSTP has a BOD below 30 PPM. This confirms to the discharge standards of Central Pollution Control Board in India.
How do you install the tank? All tanks are easy to install as the GEPSTP have a flat bottom. The tank should be positioned on a concrete base / hard surface and then backfilled with a sand or lean concrete mix. Installation videos and manual are available in downloads section.
When should the tank have to be emptied? It depends on how much use the system gets - for a full family using the system in a main residence, the system should be emptied annually. If the system is used infrequently, in a holiday home for example, then every 3 -4 years maybe sufficient.
Should I put extra bacteria inducing sachets into the tank on a regular basis? It is always a good idea to maintain the tank and ensure that there are enough bacteria. This becomes an additional advantage where the usage of the plant is not regular. We can provide such enzymes / bacteria at a nominal cost.
How does a GEPSTP work? Air is blown into the GEPSTP by an electrically powered compressor mounted normally within 10 metres of the sewage treatment plant. The air is diffused from the bottom of the central chamber. This increased oxygen supply accelerates the activity of the naturally occurring micro-organisms which degrade the sewage to a clear effluent and a non toxic sludge. The plastic media is used to provide a high surface area for the micro-organisms to adhere to and also, as it is mobile, to facilitate rapid degradation of solid matter. The diffused air also operates as an ‘Air Lift’ which recirculates solids from the outer ‘Settlement Chamber’ to the inner ‘Treatment Chamber’. This recirculation also ensures that both chambers remain aerobic. The process runs continuously 24 hours a day.
How long does it take to work? About four to six weeks from start up. You can accelerate this by seeding the unit with the sludge from an operational aerobic sewage treatment system.
I have a pond on my land, can I discharge the treated effluent into it? The answer is dependent on the size of the pond, size of the discharge and whether there is a flow through the pond. ‘Consent to Discharge’ may be required.
Do you install the GEPSTP? In some areas we have independent contractors who specialize in installing sewage disposal systems. More contractors are required. Please ask for details.
What is BOD5? BOD stands for Biochemical Oxygen Demand. ‘5’ stands for a test that takes 5 days to carry out. The test is essentially a measure of the ‘Organic’ or ‘Polluting’ strength of an effluent. A measured sample is prepared for incubation and the oxygen level is determined. The sample is than incubated for 5 days at 20°C and the oxygen level is measured again. The difference in oxygen levels is used to calculate the BOD5. This represents the level of activity by micro-organisms naturally present in the effluent. The level of activity is proportional to the ‘Organic’ or ‘Polluting’ strength. If an effluent is too strong for a receiving aquatic environment then oxygen will be naturally depleted in the same process. Mg/l stands for Milligrams per litre. One Mg/l is the same as one part per million. Untreated sewage typically has a BOD5 of 300-350 mg/l. The GEPSTP reduces this to less than 30mg/l.
Can I use normal household cleaning chemicals? All normal products can be used in sensible quantities. Don’t forget that the system works by accelerating the natural sewage degradation process. Some chemicals used are designed to destroy micro-organisms. So, overuse of bleach or antibacterial cleaners may upset the process. You should avoid products containing ammonia where the ‘Consent to Discharge’ has a limit for Ammoniacal Nitrogen. Avoid allowing significant quantities of grease to enter the system. Where there is a commercial kitchen (Hotels, Pubs etc) a grease trap must be fitted to the kitchen drainage only.
What is population equivalent? Population Equivalent relates to non domestic sewage treatment plant applications. For example an office with 30 workers is equivalent to 10 domestic residents. ie the PE is 10. This becomes more complicated for Pubs/Hotels etc. Please refer to the programme on this site for specific details. Pubs typically have a PE in the range 40-200.
What is GEPSTP10? GEPSTP10 is a 10,000 lts per day Domestic Sewage Treatment Plant, and uses the advanced Moving Bed Bio Reactor (MBBR) technology.
What does it do? It captures and treats all household wastewater from the kitchen, bathrooms, toilets, laundry etc, for reuse on gardens/lawns.
How does it work? As soon as you press the button or pull the plug, the wastewater enters the GEPSTP sewage treatment plant to begin the aerobic treatment process. This is where a complete digestion of organic waste takes place in the oxygen rich environment, using naturally occurring bacteria. The organic waste entering the tank is treated to high quality water for reuse. This water is decanted and disinfected, then goes into an effluent holding compartment. When a sufficient amount of water has entered this compartment, a float switch turns the effluent pump on and pumps the treated water out through the irrigation line onto gardens and lawns.
What is the Aerobic Process? Aerobic means the presence of oxygen. This treatment process is very efficient, with breakdown occurring in a matter of hours in the oxygen-enriched environment. The same process is used by modern day council treatment plants world-wide.
What is Effluent? Effluent is the treated water at the end of the treatment process. Does the GEPSTP Sewage Treatment Plant produce any nasty odours? No. Due to the aerobic process the waste does not decompose and smell. How much noise does GEPSTP Sewage Treatment Plant make? Due to the selection of equipment involved, there is only a low humming sound when the plant is in operation. I like to do a number of loads of washing on one day, will this overflow the system? A shock load – like multiple washing loads, extra visitors, emptying a spa bath etc is easily handled by our Sewage Treatment Plants. How often does the Sewage Treatment Plant need to be serviced? Yes, a service is to be carried out every 6 months. Results from the tests for water purity and system efficiency are provided to you and your local authority.
Do I get a user manual with the Sewage Treatment Plant? Yes. The User Manual can be found in the control box, it is very informative, telling you all you need to know about how your plant. Soft copies can be downloaded from the downloads section in our website.
Does the plant make a noise? Modern compressors are virtually silent, contained within housings further reducing noise levels.
Who will install the GEPSTP / GEST or other products of Indus?
All our products must be installed by our authorized channel partners only. The warranty can activated only after such installation and commissioning.
Will paper towels, sanitary towels, etc, clog up my system? Sanitary towels and similar non-biodegradable products should not be flushed into any wastewater treatment products. For a complete listing of restricted items see the Do’s and Don’ts guide in the downloads section of our website or request our customer care to send you one.

How do I obtain my “Consent to Discharge”? Contact your local environment agency. Will I need a Septic Tank or a Sewage Treatment Plant? Product selection depends on the specifics of location and method of water dispersal. Typically if discharging to surface waters then a sewage treatment plant must be selected which conforms to the minimum effluent quality of that countries environmental agency. Septic Tanks are not allowed to discharge to surface waters. If a soakaway disposal system is to be used then usually a septic tank can be used although a sewage treatment plant is a requirement in some cases. If in any doubt it is recommended to contact the local environmental agency as requirements can be subject to other factors. How big is the plant? Please refer to the specific product drawings for dimensions, available for download on the website.