Handbook on Water Supply and Drainage (with Special Emphasis on Plumbing)

IS SP 35 (S&T) - 1987: Scope & Key Specifications

This handbook coordinates water supply and drainage design, referencing detailed IS standards for construction, testing, and maintenance.

Key Formulas & Tables:

1. Equivalent Pipes (Clause 4.14):
Pipes are equivalent if they carry the same flow rate with the same head loss.

2. Hazen-Williams Formula (for head loss in pipes):
[ h_f = K_1 \frac{L}{D^{4.87}} Q^{1.85} ]
Where:

• (h_f) = head loss (m)
• (L) = length of pipe (m)
• (D) = diameter (m)
• (Q) = flow rate (m³/s)
• (K_1), (K_2) = coefficients from tables based on pipe roughness and Hazen-Williams coefficient (C).

3. Table 4: Values of (K_1) and (K_2) for different (C) (Hazen-Williams coefficient):

4. Table 5: Roughness Coefficients (n) for Pipe Linings (Manning's n):

IS SP Part 35: Glossary of Terms & Key Specifications

1. Glossary Reference:

• Follow IS:10446-1983 for water supply and sanitation terminology.

2. Head Loss & Equivalent Pipes (Clause 4.14):

• Pipes are equivalent if they carry the same flow rate with the same head loss.

3. Hazen-Williams Coefficients (Clause 4.10 & Table 3):

4. Values of K₁ and K₂ for Different C (Table 4):

5. Roughness Coefficients (n) for Different Linings (Table 5):

IS SP:35 (S&T) - 1987: Water Supply Requirements & Design

Key Specifications:

• Continuous 24-hour supply is essential for adequate pressure and hygiene (Clause 5.1.5).
• Design pressures must ensure adequate pressure at all points; intermittent supply is discouraged.

Water Consumption for Buildings Other Than Residences (Table 12, Clause 5.1.4):

Note: For stations and airports, consider average daily passengers plus staff/vendors.

Design Formulas for Pipe Sizing:

• Pressure pipes: Use Hazen-Williams formula for head loss and diameter calculation.

  [ h_f = 10.67 \times \frac{L}{C^{1.852} \times d^{4.87}} \times Q^{1.852} ]

  Where:

  • (h_f) = head loss (m)
  • (L) = pipe length (m)
  • (C) = Hazen-Williams roughness coefficient
  • (d) = pipe diameter (m)
  • (Q) = flow rate (m³/s)

• Free flow conduits: Use **

Key Formulas for Flow of Water in Pipe Systems (IS SP Part 35)

1. Hazen and William's Formula (Flow under pressure)

[ V = 0.849 , C , R^{0.63} \times S^{0.54} ]

• V = velocity (m/s)
• R = hydraulic radius (m)
  For circular pipes, ( R = \frac{D}{4} ) where (D) = diameter
• S = slope of hydraulic gradient (m/m)
• C = Hazen and William's coefficient (depends on pipe material)

2. Manning's Formula (Free flow conduits)

Used for open channel flow (not detailed here, but important for free surface flow).

Table: Recommended Hazen and William's Coefficient (C) (Clause 4.10)

Resistance Coefficients (K) for Pipe Fittings and Valves (Clause 4.12.1)

Key Specifications for Water Treatment & Quality (IS SP Part 35)

1. Water Treatment Methods (Clause 5.3.1)

• Treatment depends on raw water quality & desired standards.
• Unit operations include:
  • Aeration
  • Flocculation
  • Clarification (Sedimentation)
  • Filtration (Slow sand, Rapid gravity)
  • Disinfection (Chlorination)
  • Softening (for hardness)
  • Deferrization, Defluoridation
  • Water conditioning
• Treatment examples:
  • Groundwater with turbidity <10 JTU: chlorination only.
  • Groundwater with iron/CO2: aeration → flocculation → sedimentation → filtration → chlorination.
  • Surface water turbidity <50 JTU: sedimentation → slow sand filtration → disinfection.
  • Highly polluted surface water: conventional treatment (pre-chlorination, aeration, flocculation, sedimentation, rapid filtration, post-chlorination).

2. Bacteriological Standards (Clause 5.1.6.2)

3. Physical & Chemical Standards (Table 13, Clause 5.1.6.1)

Key Formulas & Specifications for Plumbing Fixtures & Sanitary Appliances (IS SP Part 35, Clause 5.6.3.3)

1. Fixture Unit Concept

• 1 Fixture Unit (FU) = 1 cubic feet per minute (cfm) flow rate.
• Total discharge flow = Sum of fixture units × probability factor (Hunter's curve, Table 32).

2. Design Basis

• Based on:
  • Number & type of fixtures
  • Fixture unit flow rate
  • Simultaneous use probability

3. Fixture Unit Values & Branch Sizes (Table 30)

4. Fixture Unit Values Based on Drain/Trap Size (Table 31)

5. Special Notes

• Service sinks

IS SP Part 35: Drainage and Sewerage Systems – Key Points

1. Formulas for Pipe Design

• Hazen-Williams Formula (for pressure pipes):

  [ V = k \cdot C \cdot R^{0.63} \cdot S^{0.54} ]

  Where:

  • ( V ) = velocity of flow (m/s)
  • ( C ) = Hazen-Williams coefficient (depends on pipe material)
  • ( R ) = hydraulic radius (m)
  • ( S ) = slope of energy grade line (m/m)
  • ( k ) = conversion factor (usually 0.85 for SI units)

• Manning’s Formula (for free flow conduits):

  [ V = \frac{1}{n} R^{2/3} S^{1/2} ]

  Where:

  • ( n ) = Manning’s roughness coefficient
  • ( R ), ( S ) as above

2. Hazen-Williams Coefficient ( C ) for Different Materials (Table 3)

3. Design Considerations

• Use Hazen-Williams for pressure pipes (plumbing, sewer under pressure).
• Use Manning’s formula for open channel flow (free flow conduits).
• Refer to Tamil Nadu Water Supply and Drainage Board tables for detailed Hazen-Williams design charts.
• For septic tanks

IS SP Part 35: Pumping and Sewage Handling - Key Points

1. Pumping of Sewage (Clause 6.11 & 6.11.1)

• Sewage from low-lying areas or sub-basements often requires pumping due to gravity flow limitations.
• Pumps must be non-clogging and automatically controlled to handle solids and grit in sewage.
• Typical pump diameter range: 50 to 150 mm for small stations.

2. Design Formulas

• Pressure Pipes: Use Hazen-Williams formula for head loss calculation:

  [ h_f = 10.67 \times \frac{L}{C^{1.85} \times d^{4.87}} \times Q^{1.85} ]

  Where:

  • (h_f) = head loss (m)
  • (L) = length of pipe (m)
  • (C) = Hazen-Williams roughness coefficient
  • (d) = diameter (m)
  • (Q) = flow rate (m³/s)

• Free Flow Conduits: Use Manning's formula for velocity:

  [ V = \frac{1}{n} R^{2/3} S^{1/2} ]

  Where:

  • (V) = velocity (m/s)
  • (n) = Manning’s roughness coefficient
  • (R) = hydraulic radius (m)
  • (S) = slope of energy grade line

3. Specifications

• Pumps must be designed for sewage with solids and grit.
• Avoid food valves by using non-clogging pump designs.
• Pump stations should have automatic controls to prevent sewage accumulation.

Summary Diagram: Sewage Pumping System

flowchart LR
    A[Low-Lying Sewage Collection Point] --> B[Pumping Station]
    B --> C[Treatment Plant]
    C --> D[Stabilization Ponds / Disposal]
    B -.->|Automatic Control| A

For detailed design, refer to the appendices for septic tanks, water supply, and pipe design charts in IS

Maintenance of Sewerage Systems (IS SP Part 35 - Clauses 6.10.6.2 & related)

Key Points:

• Maintenance Types:

  • Preventive: Routine work to avoid breakdowns; economical and ensures reliability.
  • Corrective: Repairs after failure; necessary despite preventive efforts.

• Causes of Sewer Clogging:

  • Grit/detritus deposition → stagnation → odours/gases.
  • Grease deposits from kitchen wastes.
  • Root penetration through joints/cracks.
  • Fungal growth obstructing flow.
  • Stagnation due to pump failure or solid waste dumping.

• Safety Equipment for Maintenance:

  • Gas masks, oxygen apparatus.
  • Portable lighting, non-sparking tools.
  • Air blowers, safety belts, inhalators.
  • Use depends on gas detection & oxygen levels.

Design Consideration:

• Maintenance needs must be integrated during design and construction.
• Refer to Hazen-Williams formula for pressure pipes and Manning's formula for free-flow conduits for hydraulic design.

Important Formulas:

flowchart LR
    A[Maintenance of Sewerage System] --> B[Preventive Maintenance]
    A --> C[Corrective Maintenance]
    B --> D[Routine Cleaning & Inspection]
    C --> E[Repair & Rehabilitation]
    A --> F[Safety Equipment]
    F --> G[Gas Masks]
    F --> H[Oxygen Apparatus]
    F --> I[Non-sparking Tools]

Safety in Sewer Maintenance (IS SP Part 35, Clause 6.10.6.2)

Key Points:

• Maintenance Types: Preventive (routine) and Corrective (post-breakdown).
• Causes of Sewer Clogging:
  • Deposition of grit, grease, organic matter → odours, poisonous gases.
  • Root penetration through joints/cracks.
  • Fungal growth causing flow obstruction.
  • Stagnation due to pump failure or solid waste dumping.

Safety Equipment:

• Gas masks and oxygen breathing apparatus (for toxic/oxygen-deficient atmospheres)
• Portable lighting equipment (intrinsically safe)
• Non-sparking tools (to avoid ignition)
• Portable air blowers (ventilation)
• Safety belts (fall protection)
• Inhalators (emergency breathing aid)

Safety Procedure:

• Always detect gases and oxygen levels before entry.
• Use appropriate safety gear based on gas detection.
• Ensure ventilation and continuous monitoring during maintenance.

Hazen-Williams Formula (for pipe flow design reference):

[ V = k \cdot C \cdot R^{0.63} \cdot S^{0.54} ]

Where:

• (V) = velocity (m/s)
• (C) = Hazen-Williams coefficient (see table below)
• (R) = hydraulic radius (m)
• (S) = slope of energy grade line (m/m)
• (k) = conversion factor (usually 0.85 for SI units)

Recommended Hazen-Williams Coefficient (C) (Design Values):

flowchart TD
    A[Start Sewer Maintenance]

Key Formulas & Tables for Measurement and Testing of Water and Sewer Lines (IS SP Part 35)

1. Measurement of Sewer Lines (Clause 7.4)

• Measure sewer lines by length, diameter, and type of pipe.
• Include manholes, junctions, and special fittings separately.
• Volume or flow measurement typically involves pipe diameter (D) and velocity (V).

2. Measurement of Water Lines (Clause 7.3)

• Measurement based on pipe length, diameter, and type.
• Include fittings, valves, and appurtenances.
• Testing involves pressure tests and leakage tests per IS standards.

3. Hazen-Williams Formula for Flow in Pipes

Used for water flow under pressure:

[ V = k \cdot C \cdot R^{0.63} \cdot S^{0.54} ]

Where:

• (V) = velocity (m/s)
• (C) = Hazen-Williams coefficient (depends on pipe material)
• (R) = Hydraulic radius (m)
• (S) = Slope of hydraulic grade line (m/m)
• (k) = Conversion factor (usually 0.85 for SI units)

4. Recommended Hazen-Williams Coefficient (C) (Table 3, Clause 4.10)

Summary

• Use Hazen-Williams formula with appropriate (C

Installation and Protection of Pipes (IS SP Part 35)

Key Specifications (Clause 5.5.6.2)

• Handling: Use inclined planes or chain blocks to avoid impact during loading/unloading.
• Trench Width: Free working space on each side of pipe = max(1/3 pipe dia, 15 cm).
• Laying Direction: Pipes laid downhill; socket ends face upstream if spigot/socket joints.
• Foundation: Use concrete cradle if natural foundation inadequate:
  • Concrete depth below pipe bottom ≥ 1/4 internal diameter (10–30 cm range).
  • Concrete extends up sides ≥ 1/4 diameter for larger pipes.

Classification of Concrete Pipes (Table 19)

Hydraulic Design Parameters

• Hazen-Williams Formula:
  [ V = k \cdot C \cdot R^{0.63} \cdot S^{0.54} ] where (V) = velocity, (C) = roughness coefficient, (R) = hydraulic radius, (S) = slope.

• Recommended Hazen-Williams C values for new pipes:

Key Specifications & Formulas from IS SP:35 (S&T)-1987 for Valves, Meters, and Controls

1. Sluice Valves (Clause 5.5.12.2)

• Purpose: Stop or vary flow in pipelines; placed at summits or strategic points.
• Size:
  • Up to 300 mm mains: valve size = main size
  • Above 300 mm mains: valve size ≈ 2/3 main size (min 300 mm)
• Materials (Table 26):

• Operation: Internal or external screw; gearing (bevel, spur, worm) used for large valves.
• By-pass valves: Used to relieve upstream pressure for easier operation.

2. Automatic Valves (Clause 5.5.12.3 & Table 28)

3. Flow Resistance Coefficients for Valves (Table 7)

Key Formulas & Tables for Peak Flow and Hydraulic Considerations (IS SP Part 35):

1. Peak Flow Factors (Clause 6.10.3.6)

• Used to estimate peak flow in sewer design for self-cleansing velocities and avoiding deposition.

2. Hydraulic Formulas (Clause 4.11 & 4.12)

• Manning's Formula (for free flow conduits):

[ V = \frac{1}{n} R^{2/3} S^{1/2} ]

Where:

• ( V ) = velocity (m/s)

• ( n ) = Manning’s roughness coefficient

• ( R ) = hydraulic radius (m)

• ( S ) = slope of energy grade line

• Hazen-Williams Formula (for pressure conduits):

[ V = k \cdot C \cdot R^{0.63} \cdot S^{0.54} ]

Where:

• ( V ) = velocity (m/s)
• ( C ) = Hazen-Williams coefficient (depends on pipe material)
• ( R ) = hydraulic radius (m)
• ( S ) = slope (head loss per unit length)
• ( k = 0.85 ) (unit conversion factor)

3. Hazen-Williams Coefficient (C) (Table 3)

IS SP Part 35: Backflow Prevention & System Integrity - Key Points

1. Head Loss & Resistance Coefficients

• Head loss in pipes and fittings is critical for system integrity and preventing backflow.
• Use resistance coefficient ( K ) for fittings/appurtenances (Table 7):

2. Head Loss Calculation Formula

[ h_f = K \frac{v^2}{2g} ]

• ( h_f ) = head loss (m)
• ( K ) = resistance coefficient
• ( v ) = velocity of flow (m/s)
• ( g ) = acceleration due to gravity (9.81 m/s²)

3. Flow Capacity for Meters (Tables 9 & 10)

• Nominal meter sizes and discharges to avoid backflow and maintain system integrity: