Glossary of terms relating to water supply and sanitation
1983 Edition

IS 10446 standardizes the terminology linked to water supply and sanitation. It aims to foster consistent comprehension among engineers, architects, and contractors. The glossary aligns with international standards, notably BS 4118-1967, and focuses exclusively on defining technical terms without including design formulas or tables. This resource serves as a reference guide for terms related to water supply, sanitation, drainage, and sewage systems and complements design codes such as IS 456 and IS 1172.

This section offers standardized definitions for terms commonly used in water supply and sanitation to promote uniform understanding. It covers terminology related to distribution networks, pressure heads, sewage, stormwater, effluent, measurement units like liters per capita per day (lpcd), and fixtures such as potable water, greywater, and sanitary fittings. Although it excludes specific formulas, this glossary is vital for clear communication during planning, design, and execution of related projects.

The Air Gap is defined as the vertical space between the lowest point of the water supply inlet pipe and the overflow edge of an appliance, designed to prevent contamination by backflow. The standard specifies a minimum air gap typically not less than 25 mm. It also defines related concepts such as the depth of the water seal in traps, water seals acting as air barriers, and pipe interrupters that allow air admission to prevent siphoning.

Air Release Valves, either manual or automatic, discharge trapped air from pipelines to avoid air pockets. Variants include large orifice valves for rapid air evacuation during filling or emptying, and small orifice valves for continuous release of smaller air volumes during operation. Design considerations include orifice sizes relative to valve balls and use of discharge flow formulas to size the valves appropriately.

Air testing assesses the integrity and leak tightness of drainage pipework by applying controlled air pressure, usually between 0.5 and 1.0 bar above atmospheric pressure. The test duration is typically five minutes, during which pressure stability and absence of leaks confirm system soundness. Safety precautions and appropriate pressure ranges are emphasized to prevent damage.

Back Pressure refers to air pressure within drainage pipes exceeding atmospheric levels, potentially impeding flow. Calculations involve pressure head derived from pressure and water density. The standard outlines prevention methods including anti-vacuum valves, check valves, and vent pipes sized according to system pressures to ensure smooth drainage and avoid contamination.

A Bedpan Sink is an open appliance designed for emptying and cleaning bedpans and urine bottles. It features smooth, non-porous surfaces, flushing rims for rinsing, traps to prevent odors, and dimensions suitable for standard hospital equipment. Materials used are hygienic such as porcelain or stainless steel, with hot and cold water supply connections and proper drainage.

Bottle Filling Taps have tapered nozzles engineered to deliver a smooth, splash-free stream ideal for filling bottles. Installed typically 850 to 900 mm above floor level, they offer moderate flow rates generally between 4 to 8 liters per minute. This design contrasts with other tap types like bib taps or spray taps primarily used for washing or general usage.

Cisterns are fixed containers for water storage at atmospheric pressure, often equipped with float valves. Variants include storage cisterns, flushing cisterns designed for rapid discharge during flushing, and feed cisterns supplying cold water to hot water systems. Design involves calculating capacity based on flush volumes and maintaining water levels to prevent overflow.

The Cross Vent or Yoke Vent is a short vent pipe linking the main discharge pipe to the main ventilating pipe. Its role is to balance pressure, preventing trap siphoning and maintaining water seals. It must be short, with diameter at least half that of the main pipe, positioned near base stacks, and airtight to prevent gas leaks.

A Deep Seal Trap is characterized by a water seal depth exceeding 50 mm, serving as a barrier against sewer gases while allowing wastewater flow. Recommended seal depths range from 75 to 100 mm for effectiveness. The trap is designed to maintain the seal even under negative pressure conditions, with sizing depending on expected flow rates.

The Ferrule Key is a tool used to operate screwdown ferrule valves that control water flow from mains. Screwdown ferrules incorporate a 90° bend and a built-in valve, while swivel ferrules add a joint allowing flexible pipe orientation. The key fits the valve head to open or close flow, with dimensions and materials specified for durability.

Hot Water Tanks are pressurized vessels storing heated water for domestic or industrial use. Types include cylinder hot water tanks, indirect cylinders heated by separate circuits, and water heaters. Design follows pressure vessel codes (e.g., IS 2825), calculating shell thickness based on pressure, diameter, material strength, and joint efficiency. Insulation and corrosion resistance are also important considerations.

A Lifting Key is a tool designed for safely removing covers of manholes, inspection chambers, or surface boxes. Typically made from steel or cast iron, it must fit securely into lifting slots, provide adequate leverage, and accommodate cover weights ranging from 50 to over 100 kilograms. Ergonomic design facilitates handling.

Pipe Clips are curved clamps with fixing ears used to secure pipes to walls or structures. Variants include buffer clips with rubber inserts protecting flush pipes, saddles used for reinforcement or branching, and pipe rings which are split clamps bolted around pipes. Materials generally include galvanized steel or stainless steel, with dimensions tailored to pipe sizes.