The IS SP Part 35 (1987) serves as an extensive manual on water supply and drainage systems, emphasizing plumbing practices within the Indian context. It offers in-depth instructions on the planning, installation, upkeep, and safety of water distribution and sewage disposal networks, covering plumbing fixtures, piping materials, pumping devices, and water treatment techniques. This code is indispensable for engineers, architects, and plumbing specialists engaged in building services and municipal sanitation projects.
Overview
The IS SP Part 35 (1987) serves as an extensive manual on water supply and drainage systems, emphasizing plumbing practices within the Indian context. It offers in-depth instructions on the planning, installation, upkeep, and safety of water distribution and sewage disposal networks, covering plumbing fixtures, piping materials, pumping devices, and water treatment techniques. This code is indispensable for engineers, architects, and plumbing specialists engaged in building services and municipal sanitation projects.
Audience
Contents
Structure
The handbook integrates design considerations for water supply and drainage, citing relevant IS codes for construction, testing, and service. It introduces essential formulas such as Equivalent Pipes and the Hazen-Williams equation for pipe head loss, accompanied by coefficient tables to facilitate design accuracy.
This section aligns with IS:10446-1983 for water supply and sanitation terms. It elaborates on key concepts including head loss, pipe equivalency, and Hazen-Williams coefficients for various conduit materials.
Guidelines for continuous 24-hour water supply ensuring adequate pressure and hygiene are detailed. Per capita consumption rates for various building types are tabulated, along with formulas for pressure pipe sizing using the Hazen-Williams method.
Key hydraulic equations including Hazen-Williams and Manning’s formulas are presented for pressurized and free-flow conduits respectively. Tables provide recommended roughness coefficients and resistance factors for fittings and valves.
Describes treatment methods such as aeration, flocculation, sedimentation, filtration, disinfection, and softening. It includes bacteriological and physical-chemical quality criteria with limits for various parameters.
Introduces the fixture unit concept for load estimation, simultaneous use probabilities, and minimum branch pipe sizes. Fixture unit values for various sanitary appliances are tabulated with design recommendations for traps and drainage.
Focuses on pipe design formulas (Hazen-Williams and Manning), material-specific coefficients, and design practices for pressure and free-flow sewer conduits. Maintenance considerations are outlined to ensure system reliability.
Details pumping requirements for low-lying sewage collection points, pump specifications including non-clogging designs, automatic control features, and design formulas for head loss calculation.
Emphasizes preventive and corrective maintenance strategies to avoid blockages caused by grit, grease, roots, or fungal growth. Safety equipment usage and design integration for maintenance accessibility are discussed.
Outlines safety equipment such as gas masks, oxygen apparatus, non-sparking tools, and ventilation devices. Procedures for atmospheric monitoring and safe entry are specified to protect workers.
Describes methods for quantifying pipeline lengths, diameters, fittings, and flow velocities. Testing practices including pressure and leakage tests are explained with applicable hydraulic formulas.
Details handling, trench dimensions, laying orientation, and foundation requirements. Classification of concrete pipes and recommended protective linings are provided to ensure durability.
Covers types and sizes of sluice valves, materials used, operation mechanisms, and by-pass arrangements. Automatic valve functions and resistance coefficients for valves and fittings are included.
Presents peak flow factors based on population size to design sewer capacities. Includes Manning and Hazen-Williams formulas and tables for roughness coefficients to optimize flow and prevent deposition.
Discusses head loss and resistance coefficients for fittings and valves critical in avoiding backflow. Provides formulae for calculating head loss and tables indicating flow capacities for various meter sizes.
Frequently Asked
The standard recommends per capita water supply rates depending on community size: 70 to 100 litres/day for populations up to 10,000; 100 to 125 litres/day for 10,000 to 50,000; and 125 to 200 litres/day for populations above 50,000. These values encompass domestic and non-domestic requirements. The National Building Code (1983) advises a minimum of 135 litres per capita per day for residential areas with complete flushing. Design should consider local habits, climate, and water availability to ensure adequate supply for all uses, including firefighting and livestock.
Materials specified include reinforced concrete pipes, especially with high alumina cement for acidic or sulfate-rich soils to prevent corrosion. Metal options include cast iron and steel pipes, while plastic pipes such as polyethylene and PVC are preferred for smaller diameters. Asbestos cement pipes are also used but with caution in acidic environments. Protective barriers involve cement plaster coatings, epoxy resin linings, bitumen and coal tar coatings, and fiberglass layers. All protective applications require strict supervision to ensure effectiveness, as acid exposure can severely damage linings.
Water closets should be one-piece units with floor fixing holes, integral flushing rims, and self-draining inlets with weep holes. They must have integral traps with proper outlet slopes and are ideally placed in separate bathroom compartments. Flushing cisterns should have a 10-litre capacity with controlled discharge rates. Bath fixtures should be constructed from smooth, non-absorbent materials, installed in well-ventilated spaces with ventilation meeting IS 1256 standards. Floors must be moisture-resistant, sloped for drainage, and equipped with brass gratings. Accessories such as soap holders and towel rails should be provided, and artificial lighting must ensure full visibility.
Preventive maintenance is prioritized, involving regular removal of grit, grease, and detritus to prevent stagnation and odor formation. Root intrusion should be controlled by sealing joints and repairing cracks promptly. Fungal growth must be monitored and controlled. Proper operation and upkeep of pumping equipment prevent sewage stagnation. Disposal of solid wastes in manholes is discouraged. Corrective maintenance includes repairs and clearing blockages as needed. Safety measures, including the use of gas masks, oxygen apparatus, and non-sparking tools, are essential during maintenance activities.
Due to the hazardous nature of sewer environments, safety equipment includes gas masks to protect against toxic gases, oxygen breathing apparatus for oxygen-deficient atmospheres, explosion-proof portable lighting, non-sparking hand tools to prevent ignition, portable air blowers for ventilation, safety belts for fall protection, and inhalators for emergency breathing support. The use of such equipment is determined based on prior atmospheric gas and oxygen level measurements. Ventilation and continuous monitoring are critical during maintenance.
Peak flow factors are applied to average flow rates based on population size to estimate maximum flows, essential for designing sewer capacities that maintain self-cleansing velocities and prevent solids accumulation. For populations up to 20,000, a peak factor of 3.5 is used; for 20,000 to 50,000, 2.5; for 50,000 to 750,000, 2.25; and for above 750,000, 2.0. Additionally, design flow depths vary with pipe diameter to ensure proper ventilation and avoid pressure sewer conditions.
Treatment selection depends on raw water characteristics. For low turbidity, odorless groundwater or protected surface water, chlorination alone suffices. Groundwater containing iron or carbon dioxide requires aeration, flocculation, sedimentation, filtration, and chlorination. Surface waters with moderate turbidity are treated via sedimentation, slow sand filtration, and disinfection. Highly polluted surface waters need conventional treatment including pre-chlorination, aeration, flocculation, sedimentation, rapid filtration, and post-chlorination. Hard water may require softening processes, while water with high dissolved solids may need demineralization techniques.
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