House Drainage System By- Prajyoti P. Upganlawar Faculty, Civil engineering department, S.P.B Patel Engineering College. prajyoti.u@gmail.com

Introduction A system of conveyance of wastewater from all ( latrines, bathrooms, sinks and washbasin) to disposed into municipal sewer. This system is known as house drainage system.

Definitions Sullage – Wastewater coming from bathrooms and kitchens which doesnot contain fecal matter is known as sullage. Pumbling system – It is entire system of pipe line for providing water supply to the building or system of pipes for disposal of wastewater from building. Sewer – A pipe carrying sewage/wastewater is called sewer. Soil pipe – pipe carrying sewage from latrines.

Waste pipe – pipe carrying sullage from bathrooms, kitchen, sinks and wash basin etc. Sewerage system – a system of sewers of different types and sizes in a town collecting wastewater from the town and carrying it to wastewater treatment plant. Traps – traps are defined as fittings at the end of soil pipe or waste pipe to prevent foul gases coming out of soil pipe/waste pipe.

Principles of house drainage Location of lavatory box should be one above the another so that it requires minimum drainage line. Drainage line should be laid by side of building. Sharp bends and junctions should be avoided. Slope of drains should provide self cleansing velocity. Size of drain should be sufficient to avoid flooding while handling maximum discharge. Enough number of traps.

Intercepting trap should be provided between house drain and public sewer to avoid entry of foul gases. Connections should be water tight. Proper ventilation from starting to final point of disposal. All materials and fittings of drainage system should be hard, strong, and resistant to corrosive actions. Air locks, under deposists should be minimized.

Traps “A trap is a bent fitting which when provided in a drainage system, always remains full of water thus maintaining a water seal” It allows sewage and wastewater to flow through it and prevents entry of foul air and gases. Depth of water seal is vertical distance between crown and dip of a trap. Depth represents its strength and effectiveness. It varies from 25mm to 75mm.

Classification of traps According to shape :- p trap Q trap S trap b. According to use :- Floor or nahni trap Gully trap Intercepting trap Grease trap

p traps Legs are at right angles to each other

Q traps Two legs meet at an angle other than a right angle

S trap Both legs are parallel to each other

Nahni/floor trap Used to collect waste water from floors, kitchens and bathrooms. Made up of cast iron with grating at top to avaoid entry of solid matter of big size. Have small water seal.

Gully trap Disconnect sullage drain from main drainage system. Either made up of stone-ware or of cast iron. Square or circular in section. Water seal 60-70 mm It may have S-trap or P-trap. Provided at the external face of wall. Receives wastewater from bath,kitchen etc. and pass it on to the house drain carrying discharge from W/C etc.

Gully trap

Intercepting trap Provided at junction of house drain and public sewer. Water seal of 100mm. It has opening at top called cleaning eye having a tight plug for frequent cleaning of the trap.

Grease trap To remove oily waste from wastewater. Used in large hotels, restaurants or industries where large quantities of oily waste are expected to enter. Masonry or cast iron. Bent or tee pipe at the outlet.

Grease trap

Sanitary fittings Wash basin Sinks Bath tubs Water closets Urinals Flushing cisterns

Wash basin

Wash basin Made up of pottery, procelain, cast iron, pressed steel or plastic. Flat back pattern or angle back pattern In different shapes and size. Two taps, one for hot and other for cold. Oval shaped bowl, with an overflow at top. Waste pipe with strainer is provided at the bottom of bowl. Trap at bottom

Sink

Sink Used in kitchen or laboratory. Stainless steel, metal or pressed steel. Various shape and size. Rectangular is common shape. Outlet pipe provided with a grating of brass or nickel may discharge over floor trap.

Bath tubs Made up of iron or steel, coated with enamel, enamelled porcelain or of plastic material. Madeup of marble chips or terrazo. Length vary from 1.7 to 1.85 m width between 0.7m to 0.75m, depth 0.43 to 0.45. Provided with outlets and overflow pipe usually of 40 mm dia.

Water Closets Designed to receive wastewater from person using it. Connected to soil pipe by means of suitable trap. Connected to flushing cistern. 3 types- Indian type European type Anglo Indian type

Indian style W/C

European W/C

Anglo Indian w/c

Urinals

Urinals Two types- Bowl type Slab type Stall urinals has more than one units, with a c/c spacing of 0.6 to 0.7 m. Made up of stoneware, slate and cement. Discharging of waste into soil pipe through floor trap. Automatic flushing cisterns are generally provided in stall type which operates at regular interval of 10 to 15 mins.

Stall type Bowl type

Flushing Cisterns Cast iron (Indian type, fixed at about 2m above floor level) or procelain (European and Anglo indian type, fixed at about 60cm above floor level) Used for flushing out water closets and urinals. Two types of flushing cisterns Valveless siphonic type (bell type flushing cistern) Valve fitted siphonic type

Systems of plumbing Single stack system One pipe system Partially ventilated single stack syatem Two pipe system

Single stack system

One pipe system

Two pipe system