IS : 2470 ( Part 1 ) - 1985( Reaffirmed 2001 ) Indian Standard CODE OF PRACTICE FOR INSTALLATION OF SEPTIC TANKS PART I DESIGN ( CRITERIA AND CONSTRUCTION Second Revision ) OCTOBER 1993 Third Reprint UDC 628’352 : 69’001’3 0 Copyright 1986 BUREAU MANAK OF BHAVAN. INDIAN STANDARDS ZAFAR MARO 9 BAHADUR SHAH NEW DELHI 110002 Gr 6 January 1986 IS t 2470 ( Part 1 ) n 1985 Indian Standard CODE OF PRACTICE FOR INSTALLATION OF SEPTIC TANKS PART I DESIGN CRITERIA AND ( CONSTRUCTION Second Revision ) Refiesenting Water Supply and Sewage Disposal Undertaking, New Delhi Water Supply and Sanitation Sectional Committee, BDC 24 Chairman SHRI J. D’CBUZ Members CHIEF ENGINEER ( CIVIL I ) ( Alrnnote to Shri J. D’Cruz ) Ministry of Works and Homing ADVIYER ( PHE ) DEPUTY ADVISES ( PHE ) ( Alternate ) Public Health Engineering Department GovernSARI N. S. BHAIRAVAN ment of Kerala, Trivandrum SUPEHINTEIDINOENC+~NE~R Alterhate,) ( Publzlcrprks Department ( Pd;blic Health SHHI 1. CI~AN~RA Government Haryana, Chandig)arh Snrtr K. K. GAX~XIX ( Alfernate ) CEIEB ENGINEER(‘CONSTRUCTION) Uttar Pradesh Jal Nigam, Lucknow SUPENINTENDINQ EyofNEER ( Alternate ) SHRI R.C.P. ClIAUl,31 ‘!tY Engineers India Ltd, New Delhi Sun1 H. V. RAO ’ llternate ) SUW S, K. DASOUPTA Calcutta Metropolitan Development Authority, Calcutta SHKI S. R. MUX. ZRJEE ( Alternate ) Institution of Engineers ( India ), Calcutta Pao~ J. M. DAVE Sunr S. G. DEOLAI~. AU In personal capacity ( Flat .No. 403, Suvitri Cinema Commerical Complex, Greater Kailash -IX, New Delhi ) SHRI B. R. N. GUPTA Ministry of Defence, Engineer-in-Chief’s Branch, New Delhi Srmr K. V. KRISHANAYURTI~Y ( riltrrnarc ) ( Conlinud 0s fig0 2 ) @ Copyright 1986 BUREAU OF INDIAN STANDARDS This publication is protected under the Indian CO&right & ! r; \ \T of 1957 and ) reproduction in whole or in part hy any means except with wrirr!.:i 1,ermission of the publisher shall be deemed to bc an infringement of convrieht under the said Act. Sehgal & Co. M. e Hmdustan Bombay ! Construction SBRI C. KY~IRSAQAR ( A&ernnle) Ministry of Railways Srrrc~ RANJIT S114oa National Buildings Organization. Director ( Civ Engg ) Secretary A. GUIN ( &rrnlrfe ) SHRI A. Government of Punjab. PUTTAKEYPANNA ( Alternate )” Madras Metropolitan Water Supply and Sewerage Srrnl V. India. ~B~I~ETAI<Y GENERAL Calcutta SIIRT R. New Delhi DR A. Patiala Hindustan DoIr-Oliver Ltd. RAEUL ( Alternafe ) SHRI K. Nagpur SRRI S. Bhopal Govern- SER. MADAN SURVEYOR OF WORKS-~ (NDZ) ( $cm~C New Delhi Company Ltd. RATRA ( Albmrnfd ) Indian Watrr Works Association. KI~ANNA Pkblic Health Engineering Department. RAYAN.\~IZ PROJECTS ) ( Alternale ) SEXI R. K. Y. R. PONNABALADS Public Works Department (Public Health Branch). Snm S. Calcutta Tarniayr. PROF V.tu Water Supply & Drainage Board. New Delhi SHRI L. Madras SHRI S.IS:2470( Part I)-1985 (Continuedfrom HYDRAULIC page 1 ) Representing Municipal Bombay Corporation of Grc ater Bombay. SRRI B. NATE SHRI D. S. SHARMA Rootkee Bangalore Water Supply and Sewerage Board. SEHOAL Central Building Research Institute ( CSIR ). Mem6err ENaINEEll CHIEF ENQIX~ER (SE~ER. Bombay All India Institute of Hygiene and Public Health. KRIEIIIANAN SH~I M. IS1 ( E. IS1 SERI 2 . R. ment of Madhva Pradesh. NATARAJAN SHRI B. SHRI P. BANERJEE ( Allernate ) L. RAO ( Alternate ) SHRI S. N. R. VARADARAJAN Boaid. THYA~ARAJA Banealore SHRI H. AVASTHY Assistant Director ( Civ Engg ). E.z-o&cio Mecmbcr ) SHIII G. S. L. DAIVA~ANI ( Alternate ) Director General. R. K. BAWEJA ( Alternate II ) Central Public Works Department. A. RAXAN National Environmental Engineering Research Institute ( CSIR ). MITRA ( Alternate I ) SHR I. K. S. P.I D. N. Bombay SUXETARY Institution of Public Health Engineers. MAINI SHRI R. RAO SARI 0. V. J. has also been amended to read ‘Code of practice for installation of septic tanks : Part I Design criteria and construction’. if adequate water supply is available treatment of the liquid waste in septic tanks is recommended.5 This standard covers the design and construction of septic tank for small installations ( up to 20 persons ) as well as large installations.2. based on certain modified assumptions. 0.2. This revision incorpotxtes the following major changes. 0. 0. for the removal of the sludge has been elaborated. 0. after the draft finalized by the Water Supply and Sanitation Sectional ComGttee had been approved by the Civil Engineering Division Council.1 This FOREWORD Indian Standard ( Part 1 ) ( Second Revision ) was adopted by the Indian Standards Institution on 28 February 1985.have been covered in Part 2 of this Code. 0.3 Arrangements sewage for population 0.2. Large installation septic tanks were given in IS : 2470 ( Part 2 ) which was first printed in 1961 and subsequently revised in 1971. of septic tank. 0.1 Design criteria been given in detail.2.2. 0.6 The requirements for secondary treatment and disposal of septic tank efRuent_.2 This standard was first printed in 1963 and subsequently revised in 1968 which covered small installation.3 In unsewered areas.2. for the has 0.7 The title of the code which was originally ‘Code of practice for design and construction ofseptic tank : Part I Small installations and Part II Large installations’. for flushing. 3 . 0.4 The procedure have been smooth of for installing tanks in parallel for the treatment of more than 300 persons have been included.IS I 2470 ( Part 1) .2 Design of inlets and outlets working of the tanks.1985 Indian Standard CODE OF PRACTICE FOR INSTALLATION OF SEPTIC TANKS PART I DESIGN CRITERIA AND CONSTRUCTION ( Second Revision ) 0.2. IS : 2470 ( Part 1 ) . of good practice and 0. at any of The lowest point of the interior The greasy and other substances of a sewer or drain floating on the surface in which 2.7 For the purpose of deciding whether a particular requirement of this standard is complied with. construction and maintenance of septic tanks. 2. TERMINOLOGY 2. Sewage is held in these tanks for some prescribed period during which time the suspended solids present in the storage settle down. The settled sludge and the supernatant liquor undergoes anaerobic digestion. It is. shall be rounded off in accordance The number of significant places retained in the with IS : 2-1960*. The supernatant the following definitions shall apply.6 Unsatisfactory design. liquid discharge from a septic tank. flats. 1.3 Septic tank offers a preliminary treatment of sewage prior to final disposal. hostels and boarding schools where the number of users does not exceed 300 persons 2. public works departments and others engaged in this field.1 This code ( Part 1 ) lays down recommendations for the design. It is hoped that this code which has been prepared with a view to giving guidance on proper design. considered essential to lay down minimum standards for guidance of concerned authorities. 0. residential housing colonies. *RI&S for rounding off numerical values ( revised ).1 Effluent 2. sewage 4 .A water-tight single storeyed tank is retained sufficiently long to permit sedimentation. SCOPE 1.4 Septic Tank . the final value observed or calculated.4 This therefore code of practice represents a standard takes the form of recommendation. 2.1985 0. therefore. layout. The digestion results in appreciable reduction in the volume of sludge and reduction in organic matter in the liquid. expressing the result of a test or analysis. It is applicable to houses.0 For the purpose of this standard. will be found useful by local bodies. construction and maintenance of septic tanks. 0.3 Scum sewage. round off value should be the same as that of the specified value in this standard.2 Invert cross-section. construction and maintenance of septic tanks constitute a health hazard. The solids which are suspended in a sewage or effluent.The top water level in a tank.Pits and trenches for the disposal of sullage shall be so avoid contamination of watercourses or underground water supplies. sinks and similar appliances. 3. L. 3. 2.1 General .The liquid waste of a household or community human excreta. effluent from which should be given secondary treatment either in a biolo ical filter. Sullage wastes may be distributed crudely by throwing on the gardens or grassed areas and so dispersed and absorbed. the septic tanks are designed for foul sewage ( faecal matter and urine ) .The discharge from wash basins. upflow anaerobic filter.6 Sludge 2. of liquid including Sludge is the settled solid matter in semi-solid condition. NOTE .5 Sewage .11 Waste Water ( Sallage ) -.9 Suspended Solids .3 Under no circumstances should effluent from a septic tank be allowed into an open channel drain or body of water without adequate treatment.1.1. at least 12 m in length should not be laid at a gradient not steeper than 1 : 50 in order to minimize turbulence in the tank. DESIGN CONSIDERATIONS 3. W.8 Supernatant Liquor . every house should have arrangements for its sewage being treated in a septic tank. Surface and subsoil water should not find way into the septic 3. 2. 2.1.1 ‘tank.In unsewered areas. and other water the settled overlying 2. grease and disinfectants should not be treated in septic tank as they adversely affect the anaerobic decomposition. 2.4 Wastes containing excessive detergents.10 T.The layer solids which have separated from it.2 Normally.6 When the pumping arrangement is provided before the septic tanks the sewage from the pump should not be discharged directly into the 5 . 3. on the land or in a sub-surface disposa f system.1.1.5 Where the incoming drain is steep due to site conditions.The run-off from precipitation that flows over surface of the ground.7 Surface Water .tSt2410(Partl)-1985 2. located as to 3. 3. or may be drained to a seepage pit or dispersion trench from which it overflows into or is absorbed by the surrounding soil. the last section of the drain. 3. which does not contain human excreta.1. . 3. Anything that is likely to cause irregularity of flow should be avoided. 1. as far as possible. It should also be accessible for cleaning.1985 septic tank.2 Layout 3.1. For this purpose various sanitation facilities are equated in terms of fixtures units.4. it is taken as 3 litres per minute. where bends are unavoidable. the discharge from the pump is first lead into a tank and then the sewage is allowed to flow into the septic tank gravitationally and the provisions of 3.F. direction of flow from a branch connection should not make an angle exceeding 45’ with the direction of flow in the main pipe. NOTE .4.1.W.3 At junctions of pipes in manholes. 1 ) .1. In the design of septic tank. Normally.1 SewageJow 3.4 Septic Tank Design 3.6.3.1 D.2. 3.2. they should be long radius bend with cleaning eyes. 6 .2. 3.1. a minimum nominal The rate of pumping of sewage shall not exceed three times 3. Fixture equivalents are given in Table 1.1 Tie layout should be as simple and direct as practicable.For practical diameter of 100 mm is recommended.1 The maximum flow to the tank is based on the number of plumbing fixtures discharging simultaneously.4 A typical system is illustrated 3. 3. however.1 Septic tank should be located at a place open to sky.2.Fixture unit is a quantity in terms of which the load producing effect of different plumbing fixtures on the plumbing system are expressed on some arbitrarily chosen scale.5 shall also be observed. 3. in straight lines in both vertical and horizontal planes.3 Location arrangement in Fig. 3.IS : 2470 ( Par. as far away as possible from the exterior of the wall of building and should not be located in swampy areas or areas prone to flooding.2 The pipes shouid be laid.7 Pipe Diameter . considerations. of the layout of septic tank sewerage of Septic Tank 3. 1985 WA P GULLY TRAP 87 = Bath tub S = Sink WB = Wash basin WC = Water closet TO SECONDARY TREATMENT FIG.IS t 2470 ( Part 1 ) . 1 TYPICAL LAVOUT OF A SEPTIC TANK SEWERAGE 7 SYSTEM . 1.1 ) 1 l/2 sink l/2 1 l/2 1 sink fixture 2 1 1 2 l/2 l/2 l/2 Urinal ( with autoflush ) Urinal ( without autoflush ) Slop sink Laboratory Combination Shower bath Bath tub Drinking fountain Ablution tap Dish water 3.1985 TABLE FACILITY Water closet Bath Wash basin/kitchen 1 FIXTURE EQUIVALFNT EQUIVALENT FIXTUBE UNIT (Clause 3. NOTE 2 - discharging Probable number of fixture units are based on 70 percent fixture units simultancomly.4.4.1.IS : 2470( Part 1 ) .2 The estimated fixture units that contribute serving up to 20 persons. FOR SMALL TANKS UP TO ESTIMATED PEAK DIS$I&B~s NUMBER or FIXTURE UNITS (2) PLZ~B ABLE NUMBER OF FIXTURE UrJrrs DISCHAR~INC+ SIMULTANEOUSLY PROBABLE PEAK DISCHARGE Ipm (1) (3) 1 2 2 3 (4) 9 18 18 27 5 IO 15 20 1 2 3 4 Number of fixture units is based on the assumption that each house NOTE lconsisting of 5 persons may have one WC which will discharge into septic tank. 8 . for and for hostels and boarding TABLE 2 NUMBER OF USERS number of fixture units and the number of to the peak discharge in small installations residential housing colonies up to 300 persons schools are given in Tables 2 to 4. 2. C.1. OF USERS W.2 3.4.4.IS:247O(Partl)-1985 TABLE 3 OF ESTIMATED UaERa No.XIEN -SINK (4) 6 12 19 25 37 is based No. 1 bath and 1 PEAK DISCHARGE FOR HOSTELS BOARDING SCHOOL ( Clause 3.2 ) WASH BASIN/ KI~Y.033 ms per ms 3. OF DISCHAI~~E UNITE HO~MEHOLDS PEAK lpm (1) (2) 10 50 108 20 150 30 80 40 200 60 120 300 NOTE 1 . capita 3.Each household wash basin/kitchen sink.2 Sedimentation 3.4.4.x PEAK No. 3.1 The surface Sludge Digestion Per capita suspended required 3. DISCHARGE FOR RESIDENTIAL COLONIES ( Clause 3. for sludge digestion sludge is normally 3. BATA PROBABLE PEAK DISCHAI~QE lpm (6) 76 130 205 270 400 fixture units (3) 6 6 12 12 19 19 25 25 37 37 peak NOTE --Probable discharging simultaneously.3 A minimum depth of sedimentation solids entering shall be 250 to 300 mm. the tank may be taken is 0.4.2 ) Pnon. OF FIXTURE 1 JNITS AND No.Probable peak discharge is based on 60 percent fixtures ing simutaneously NOTE 2 .4.4.1 as 70 g/day.3 Volume of digested capita per day.3. OF FIXTURE No.3.\ar. (1) (2) 50 188 150 200 300 discharge (5) 12 24 38 50 74 on 70 percent of area of the tank required will be O-92 ms for every 10 litres per minute of peak flow rate at a temperature of 25%.1. O-000 21 per 9 .2 The capacity at 25°C.3.2.4.4. TABLE 4 ESTIMATED (3) 20 48 60 108 216 324 432 648 units diacharg- (4) consisting of 5 persons may have 1 WC. 3. For tanks not more than 1200 mm wide.4. 3.5 times the nominal bore of the inlet bends in other direction.4.1 A septic tank designed on the basis of 3. It is important that the invert of the benched channel be 58 mm above the top water level and the inlet ends of the submerged bends should be set flush with the floor of the sump which should be not less than 75 mm below top water level.4.3 For circular tanks the minimum diameter shall not be less than l-35 m and operating depth shall not be less than 1-O m.4. The sump may be the full width of the chamber.5 Outlet .5. extending 150 mm below the invert of the inlet pipes and 150 mm above the top water level.4. 3. Suitable sizes of septic tanks are given in Appendix A. 4.2 and 3. A baffle should be provided 150 mm from the inlet end of the tank. 3i4.1 Septic tank shall have minimum width of 750 mm.4.5 Dimensions of Sektic Tank 3.5. but should not exceed 1. with top limb rising above scum level and the bottom limb extending about 300 mm below the top water level.The final outlet for tanks which are less than 1 200 mm wide should be by 100 mm nominal bore dip-pipe fixed inside the tank with a top limb rising above scum level and the bottom limb extending to about l/3 of the liquid depth below top water level. 10 . Typical sketch of the septic tank is shown in Fig.4 Inlet . 3. 3. the length of the tank shall be 2 to 4 times the width.3 provides a detention period of 24 to 48 hours based on an average daily flow of sewage.4 Detention Time 3. Typical sketch of the septic tank is given in Fig.IS : 2470 ( Part 1 ) . The inverts of the outlet ends of these bends should be between 300 and 525 mm below top water level in the tank. The pipe shall be fixed inside the tank.The design of septic tank inlets shall be such as to introduce the crude sewage with the least possible distrurbance of the settled sludge or the surface scum.5. T-shaped dip-pipe not less than the nominal bore of incoming drain may be provided.4.5. two or more submerged inlets are preferable. minimum depth of one metre below water level and a minimum liquid capacity of 1 000 litres.5. For tanks in excess of 1200 mm in width. The invert of the outlet pipe shall be 50 mm below the invert of the inlet pipe. 2 and 3.1985 3.4.4.2 For rectangular septic tanks.4.9. 5 ). One method of providing such inlets is by the use of submerged bends of the same nominal bore ( not less than 100 mm ) set as closely together as practical in a shallow sump formed within a small benched chamber ( see Fig.1. 1 CONCRETE 2:L SECTION All dimensions ho. the end ( outlet ) wall or by a purpose-made deflector to prevent rising particles from reaching the outlet weir. This deflector should be located 150 mm below the base of the scum board and protrude 150 mm into the tank (seeFig. MORTAR ROOF PRECAST OR REMOVABLE SLABS CONCRETE 12 mm THICK CEMENT FINISH MORTAR ICEMENT.2 ?‘YPICAL XX in millimetres.fS : 2470 ( Part 1 ) . ‘\_ BRICK CEMENT WALL IN SECTIONAL VENTILATING PIPE PLAN Z7.1989 For wider tanks. 4). SKETCH TANK OF SINGLE COMPARTMENT UP TO 20 USERS SEPTIC 11 . it is necessary to use a weir outlet extending the full width of the tank and protected by a scumboard fixed 15~ lmn from the weir and extending 150 mm above and l/3 of liquid depth below the A deflector should be formed either in the structure ‘of top water level. Suitable openings the first chamber iz twice that of the second chamber. a decanting valve should be provided in the wall dividing the two tanks.1 Floor - 4.4. The ventilating pipe may also be connected to the normal soil ventilating system of the building where so desired. 12 . should be installed and operated in parallel.4.4.1985 3. This arrangement permits -11 the flow to be passed through one To enable the top water to be unit while the other is being desludged. A minimum free board of 300 mm should be 3.walls and contents. 4.6 Partitions . the tank may be divided into two chambers by mkans of a fixed The partition shall be located so that the capacity of durable partition.Each compartment of a septic tank shall be provided with a rectangular access opening measurin.9 Access Openings and Cover . 3.1. not less 455 x 610 mm or a circular opening 500 mm diameter. The cover to A cover access openings shall be of reinforced concrete or of cast iron. *Code of practice for plain and reinforced concrete ( thirdrevirLn ). SEPTIC * TANK CONSTRUCTION It is essential that the floor of the tank be water tight and of adequate strength to resist earth movement and to support the weight of the tank .8 Fret-Board provided. Generally the ventilating pipe may extend to a height of about 2 m when the septic tank is at least 20 m away from the nearest building and to a height of 2 m above the top of the building when it is located closer than 20 metres. The ventilating pipe shall extend to a height which would cause no smell nuisance to any building in the area. rectangular or circular with minimum dia 100 mm and maximum 150 mm shall be provided in the partition at approximately 300 mm below TWL. 3.1 The floor may be of cement concrete of minimum M 15 grade ( see IS : 456-1978* ) and a minimum slope of 1 : 10 may be provided towards the sludge outlet to facilitate desludging.fS I 2470 ( Part 1 ) . The bop of the pipe shall be provided with a suitable cage of mosquito proof mesh. each providing half the total calculated capacity required. 3. duplicating tanks.4.Where the capacity of a septic tank exceeds 2 000 litres.4.7 For population of over 100. the invert of this valve should be 625 mm below TWL. shall incorporate a suitable lifting device and when in place after installation of the septic tank shall fit neatly and be sealed to prevent the ingress of water. decanted when desludging.10 Ventilating Pike . 4.Every septic trek shall be provided with ventilating pipe of at least 50 mm diameter. -OPENING CONCRETE n iMEM1 FINISH 1~2 1. in millimetres.tS : 2470( Part 1) . CEMENT CONCRETE L CpN&iTE IN CEMENT OR BRICK MOklAR SECTION XX All dimensions Fro.1985 OUTLEl . CONCRETE PRECAST ROOF OR REMOVABLE SLAGS . SECTION YY 3 TYPICAL SKETCH OF Two COMPARTMENTSEPTIC TANK FOR POPULATION UP TO 50 13 .. . TX BRICK WALL IN CEMENT MORTAP 0 50 min. IS : 2470 ( Part 1 ) .1985 .BENCHING SECTION All dimensions Ika. 4 XX in millimetres.. TYPICAL SKETCH OF Two COMPARTMENT SEPTIC TANK FOR POPULATIONS OVER 50 14 . 5 TWIN INLET FOR TANKS IN EXCESS 1200 mm WIDE OF 15 .1985 SECTION All dimensions XX in millimetres. Fro.IS I 2470 ( Part 1 ) . ‘IS : 2470 ( Part 1 ) . Small domestic tanks. 6.3 The digested sludge should be withdrawn through a dip pipe of not less than 150 mm dia under a hydrostatic pressure of at least 450 mm. thir scum is needed to ensure efficient operation.2. may be cleaned at least once in 2 years provided the tank is not overloaded due to use by more than the number for which it is designed.2 Walls built out of brick should not be less than 200 mm thick and should be plastered to a minimum thickness of 12 mm inside and outside with cement mortar not weaker than 1 : 3. preferably.1 When removal of the sludge is carried out the scum in the first tank should not be disturbed more than necessary. the tanks are cleaned when tha sum of the depth of the scum and the sludge is observed to exceed half the depth of the tank.3. 5.2 Walls The walls should be of such thickness and watertightness.4 Sludge from septic tanks may be delivered into covered pits or into a Spreading of sludge on the suitable vehicle for removal from the site.1 The sewerage before connection system should be complete is made to the building. for economic reasons. Portable pumps may also be used for desludging in which case there will be no need for sludge pipe or sludge pump. 5. where they are built out of the stone masonary. 5. 6. as to provide adequate strength 4. NOTE .1 Half yearly or yearly desludging of septic tank is lesirable.2 A portion of sludge not less than 25 mm in depth should be left behind in the tank deposits. bottom which acts as the seeding material for the fresh 5.2 The tank shou!d be filled with water to its outlet level before the sewerage is let into the tank.1985 4. It should. ground in the vicinity should not be allowed. SLUDGE WITHDRAWAL 5. They should have a minimum thickness of 370 mm. Normally. Manual handling of sludge should be avoided.Frequent desludging inhibits the anaerobic action in the tank. COMMISSIONING OF SEPTIC TANK and ready for operation 6. 5. The sludge pipe shall deliver the sludge to the sump and be provided with a delivery valve to draw the sludge as required. be seeded with small quantities of well digested sludge obtained from septic tanks or sludge 16 . that discharge NOTE 3 . 7.1985 digestion tanks. ( see ).05 1’40 2’00 1’80 (1) 5 10 i5 20 NOTE 1 .0 1’0 1’3 l-3 ( CLYAPI’INOINTERVAL OF ) ~ 2 Year (5) In 1. : Part 2 Secondary treatment and 17 .4.5 2-o 2.The capacities are recommended on the assumption from only WC will be treated in the septic tank. Recommended Table 5.75 0.The sizes of septic tank are based on certain assumptions while choosing the size of septic tank exact calculations shall be made.1 Effluent from the septic tank shall be methods given in IS : 2470 ( Part 2 )-1985*.4 *Code of practice for installation of septic tank disposal of septic tank effluent ( second revision ). sizes OF SEPTIC of septic TANK for 20 users are given in tanks TABLE No. NOTE 2 ‘4 provision of 300 mm should be made for free board.90 0’90 1’10 (4) m 1. APPENDIXA ( Clause3.IS : 2470 ( Part 1 ) . 3.5._---A__h---1 Sear (2) In 1.2 ) SIZES A-l. OF USERS 5 RECOMMENDED LENo’fH SIZES OF SEPTIC BREATITH TANK FOR 20 USERS LIQUID DEPTH . In absence of digested sludge a small quantity of decaying organic matter. such as digested cow dung may be introduced. DISPOSAL OF SEPTIC TANK EFFLUENT disposed of by one of the 7.0 2’3 (3) m 0. A-2.The sizes of the septic tank are based on certain assumptions 3.0 1. NOTE 2 .The sizes of the septic tank are based on certain assumptions ( se8 3.4 ) while choosing the size of septic tank.0 (5) lT4 1’24 1’24 1’24 (1) 50 100 150 200 300 NOTE 1 - (2) m 5’0 7’5 10’0 12’0 15. into independent . the tank may be divided parallel chamber for ease of maintenance and cleaning. OF USERS L R Lxgurn DEPTH (D) FOR STATED INJXRVALS or SLUDGE WITHDRAWAL *-------_ c------Once in a Year Once in 2 Years (4) T3 1’4 1.0 (3) 2: 2’65 3.0 3. the tank may be divided into independent parallel chambers for ease of maintenance and cleaning.3 9’0 1’24 A provision of 300 mm should be made for free board. while choosing the size of septic tank exact calculation shall be made. TABLE 7 RECOMMENDED SIZES OF SEPTIC TANKS AND BOARDIN& SCHOOLS LENQTE WIDTH FOR HOSTELS No.1 2’4 2. Recommended for housing colonies ( up to schools are given in Table 6 6 RECOMMENDED OF LENCSTE SIZES OF SEPTIC COLONIES BREADTH TANKS FOR RESIDENTIAL USEKS LIQUID DEPTH (CLEANINQ INTERVAL OF) ---_--~ r---2 Year 1 Year (4) m 1’0 1.1985 sizes of septic tank 300 persons ) and for hostels and boarding and 7 respectively.7 3’3 A provision of 300 mm should be made for free board.For population over 100.For population over 100.4 ).IS : 2470 ( Part 1 ) . NOTE 3 .4 1’4 1’4 (5) m 1’4 1’7 1’7 1’7 1’7 ( see (‘1) 50 100 150 200 300 NCITE 1 - (2) m 5’0 5’7 7’7 8’9 10. NOTE 2 . exact calculation shall be made. NOTE 3 .0 1’0 1.7 (3) m 1’6 2. TABLE NO. GOVINDBN NAIR . MATHUR SHRI C. A. T. New Delhi SARI 0. N. GovernSARI K. Nagpur SHRI C. MHAISALKAR SRRI . K. 17th SHRI DEVENDRA SINQR Road.. K. K. K. GovernSEIU S. Trivandrum SRRI N. DEOLALIEAR Municipal Corporation BDC 24 : 1 of Delhi.z. HYDRAULIC ENGINEER Bombay CHIEB ENQINYEIC SEWERAOE ) ( Alternate ) ( Public Health Engineering Department. Engineer-in-Chief’s Pnop Y. L. New Delhi ) Delhi Fire Service. S. K~RDILE ( Alfernafe ) Branch (Ministry of Defeuce) . D’CRUZ SHRI S.:. V. saoilri Cinema Commetcial Complex. DHORI SHRI R. Roorkee Dn R. Delhi In personal capacity ( 403. New Delhi SHRI S.ra Engineering Research Institute. N.“. Bombay Municipal Corporation of Greater Bombay SHRI A. B. MITRA ( Alternate I ) SRR~ I. SHILI K. K. G. S. SHARMA 19 . Members SHRI J.1985 ( Continuedfrom jage 2 ) Water Supply and Plumbing Subcommittee. SWAMY ( Alternate ) SHRI S. TOSIINIWAL ( Alternate ) Tarn. A. Bombay SHRI V. Water Supply and Drainage Board. .. A. G. SHRI P. ment of Kerala. BHAII~AVAN ( Alternate ) tiah. I Bhoual . KHARE ment of Mabarashtra. P. GOVINDA MESON SIIRI T.~~ ( Altcrnatc ) Public Health Engineering Department. P. PARACAU( Alternate ) National Building3 Organisation. NA~AR~AR SHRI V. KHAXNA ment of Madhva Pradesh. BHARDWAJ ( Altetnale ) In personal capacity ( 16A Maya Mahal. Khar. RAMACHANDRA RAO New Delhi MAJ B. Greater Kailash-ZZ. GovcmSHRI R. BAWEJA ( Alternate IL ) Public Health Engineering Department. Bombay ) Municipal Corporation of Greater Bombay.IS : 2470 ( Part 1 ) . CIIALPATI~. SHRI D. NIRAY ( Alternate ) University of Roorkee.J. . RATRA Cen~~r~eueildings Research Institute ( CSIR ). SHRI S. SRIXIVASAN ( Alternate ) National Environmental Enaineerina Research Institute ( CSIR ). S. S. KULKARNI ( Bombay Fire Brigade ). 331 13 75 Telegrams : Manaksanrtha ( Common to all offices ) Telephones Regional Oflees: Central : Manak Bhavan. Sector 35-C. 9 Bahadur Shah Zafar Marg. Barua Road. University P. Campus. P. NEW DELHI 110002 Talephones : 331 01 31. 26346 [ 26349 AHMEDABAD 380001 38 49 55 SPeenya Industrial Area. Palayam 1621 17 TRIVANDRUM 695035 lnspecflon Oflce (With Sale Point) : Pushpsnjali. I.C. Ward No. Naramlmharala Squars Iangaloro 560002 Prlntod at Slmco Prlntlng Prwr. T. 1331 01 31 NEW DELHI-l 10002 3311375 . Grant Road. C Scheme. Bombay 400007 SSales Omce In Bangalore Is at Unity BulldIng. 1 st Stage. KANPUR 208006 121 82 92 6 23 05 Patliputra Industrial Estate. Manak Bhavan. BHUBANESHWAR 751002 6 36 27 3 31 77 53/5. T. N. R.. Marol. G. 5th Floor. No. BHOPAL 462003 Plot No. 29. MADRAS 600113 41 2916 tWestern : Manakalaya. 2 61 71 62435 27 66 06 60 65 26 22 66 71 Dolhl. Khanpur. NAGPUR 440010 Institution of Engineers ( India ) Building. Bangalore Tumkur Road 138 49 56 BAN GALORE 560058 66716 Gengotri Complex.T. 9 Behadur Shrh Zafar Mrrg. Lewis Road.O. 82/83. Scheme VII M. PUNE 411005 *Sales Omce in Calcutta is at 5 Chowringher Approach. GUWAHATI 781003 23 1083 5-8-66C L. T.Eastern : 1 /I 4 C. 1332 Shivaji Nagfar. Bhadbhada Road. PATNA 800013 6 21 04 T. 14/l 421.0.BUREAU OF INDIAN STANDARDS Headquarters. Nagar. 5th Byelane. 36 24 99 Maniktola. 205-A West High Court Road Shankar Nagar Square. CALCUTTA 700054 21843 Northorn : SC0 445-446. Calcutta 700072 tSales Ornce In Bombay Is at Novelty Chambers. Gupta Marg ( Nampally Station Road). I.I. Inola . 1st Floor. 6 32 92 95 BOMBAY 400093 Branch Oflces: ‘Pushpak’ Nurmohamed Shaikh Marg. Road. V. PrlncsP Street. [ 31641 CHANDIGARH 160036 41 2442 41 25 19 Southern : C. HYDERABAD 500001 63471 R14 Yudhlster Marg. JAIPUR 302005 [ 69832 21 66 76 117/418 B Sarvodaya Nagar. p. Andheri (East). E9 MIDC.