Code of practice for plumbing in multi-storied buildings, Part 1: Water supply

IS 12183 Part 1 — Scope & Key Design Data for Piping Systems

Scope (Clause 4.1)

• Covers design of piping systems catering to various plumbing fixtures.
• Fixture types and their flow rates & units are tabulated for Residential, Offices, and School/Industrial buildings.

Key Table: Rate of Flow & Fixture Units (Table 1)

Design Considerations:

• Calculate probable demand (L/s) by summing fixture units on each line (see Figure 1 in the code).
• Round off final values per IS 2-1960 rules (Clause 0.3).
• Provide electrical/mechanical design data to concerned engineers (Clause 2.4).

Formula to Estimate Demand Flow Rate:

[ Q = \sum (FU_i \times \text{Unit Flow Rate}) ]

Where:

• ( Q ) = Total flow rate (L/s)
• ( FU_i ) = Fixture units for the ith fixture

flowchart TD
    A[Fixtures Installed] --> B[Assign Fixture Units (Table 1)]

IS 12183 Part 1: General Requirements - Key Formulas & Tables

1. Fixture Units & Flow Rates (Clause 4.1, Table 1)

• Note: Concentrated use fixtures marked with * have special considerations.

2. Rounding Off (Clause None: 0.3)

• Final calculated or observed values should be rounded per IS 2-1960.
• Number of significant digits retained = same as specified values.

3. Design Coordination (Clause 2.4)

• Provide electrical & mechanical system data to the concerned engineer for integrated design.

This table helps in calculating total fixture units and required flow rates for plumbing design, ensuring compliance with IS 12183 Part 1.

flowchart TD
    A[Identify Fixtures] --> B[Assign Fixture Units from Table 1]
    B --> C[Calculate Total Fixture Units]
    C --> D[Determine Required Flow Rate (L/s)]
    D --> E[Design Piping System]

**Use these fixture units and flow rates as a basis

IS 12183 Part 1: Estimation of Water Supply Demand

Key Population Projection Basis (Clause 3.5)

Demand Estimation Notes

• Population projection is based on building usage and user information.
• For probable water demand, use fixture units (Clause 4.4.5, Figure 1) to estimate flow in litres/second.
• Demand varies inversely with hours of supply (Clause 4.4.2):
  • 24-hour supply → minimum probable demand
  • Limited hours → maximum probable demand

Typical Formula for Population Projection (Example for Offices):

[ \text{Population} = \frac{\text{Plinth Area (m}^2)}{10 \text{ to } 15} ]

Diagram: Demand Estimation Flow

flowchart TD
    A[Building Type] --> B[Population Projection]
    B --> C[Water Demand Estimation]
    C --> D{Hours of Supply}
    D -->|24 hours| E[Minimum Demand]
    D -->|Limited hours| F[Maximum Demand]

This approach ensures accurate water supply sizing based on realistic usage patterns per IS 12183 Part 1.

IS 12183 Part 1 — Design Considerations for Piping Systems

Key Specifications (Clause 4.1 & Table 1)

Piping systems must accommodate fixture flow rates and units as per Table 1:

Note: Fixture units indicate relative load and frequency of use.

Additional Design Notes

• Clause 2.3: Structural engineers must be informed about additional loads (e.g., water tanks) for structural design.
• Clause 2.4: Mechanical/electrical design data should be coordinated with concerned engineers.
• Clause 7.7: Piping system design must consider flow rates, pressure losses, and fixture units.

Typical Design Formula

To estimate total flow rate Q (L/s):

[ Q = \sum (n_i \times q_i) ]

• (n_i) = number of fixtures of type i
• (q_i) = flow rate per fixture (L/s) from Table 1

flowchart TD
    A[Fixtures] --> B[Determine number of each fixture]
    B --> C

IS 12183 Part 1 - Water Supply Sources & Permissions: Key Points

Sources of Water Supply (Clause 5.2)

• Municipal filtered water from nearby mains.
• Sub-soil sources: open wells, tubewells.
• Surface sources: lakes, rivers, canals.

Surface Water Considerations (Clause 5.5)

• Collect data on:
  • Location & water levels (high/low).
  • Flooding conditions.
  • Pumping methods.
  • Chemical & bacteriological quality (seasonal).
  • Turbidity.
• Treatment methods depend on above data.

Design Flow Rate (Fig. 1, Loading Units)

• Water demand is based on loading units (number of users/fixtures).
• Flow rate is given in liters per second (L/s) per loading unit.

Typical Design Flow Rate Table (from IS 12183 Part 1)

Permissions

• Obtain municipal approval if using municipal supply.
• For sub-soil or surface sources, permissions from local water authorities and pollution control boards are mandatory.
• Ensure compliance with water quality standards (IS 10500).

flowchart LR
    A[Water Sources] --> B[Municipal Supply]
    A --> C[Sub-soil Sources]
    A --> D[Surface Sources]
    D --> E[Quality & Level Data]
    E --> F[Treatment Decision]
    B & C & F --> G[Distribution System]

Summary: Select source based on availability and quality; gather data for surface sources; design flow rate per loading units; obtain necessary permissions.

IS 12183 Part 1 (1987) — Distribution System Key Points

1. Distribution System Design (Clause 7.1)

• Aim: Provide equitable flow and pressure to all floors in multi-storeyed buildings.
• Achieved by proper sizing and layout of pipes and fittings.

2. Overhead Tank Distribution (Clause 6.5 & 6.5.4)

• Distribution is done by down takes from overhead tanks to fixtures.
• Fig. 4 illustrates the typical layout:
  • Domestic Supply Tank → Domestic mains (kitchen, bath)
  • Flushing Supply Tank → Flushing mains (WC, urinals)
  • Both tanks fed from City Water Mains or Underground Tank.

3. Important Specifications:

• Separate tanks and mains for domestic and flushing supply to avoid contamination.
• Pipes sized to maintain minimum pressure at the highest fixture.
• Use of gravity flow from overhead tanks ensures pressure without pumps.

Typical Design Formula for Pressure Head:

[ P = \rho g h ]

• (P) = pressure at fixture (Pa)
• (\rho) = density of water (1000 kg/m³)
• (g) = acceleration due to gravity (9.81 m/s²)
• (h) = height difference from tank water level to fixture (m)

Distribution System Flow Diagram (Fig.4 style):

flowchart TD
    CityWater[City Water Mains]
    UndergroundTank[Underground Tank]
    DomesticTank[Domestic Supply Tank]
    FlushingTank[Flushing Supply Tank]
    DomesticMains[Domestic Mains (Kitchen/Bath)]
    FlushingMains[Flushing Mains (WC/Urinals)]

    CityWater --> UndergroundTank
    UndergroundTank --> DomesticTank
    UndergroundTank --> FlushingTank
    DomesticTank --> DomesticMains
    FlushingTank --> FlushingMains

Summary:

• Separate tanks/mains for domestic and flushing.
• Gravity distribution via overhead tanks with down takes.
• Design for uniform pressure/flow at all floors.
• Refer Fig.4 for typical layout.

Piping Installation & Maintenance: Key Points from IS 12183 Part 1

1. Design Considerations (Clause 4.1 & Table 1)

• Piping systems must cater to different fixtures with specified flow rates and fixture units.
• Example from Table 1:

2. Design for Water Hammer (Clause 7.7.6)

• Pipes must be designed to withstand additional pressure from water hammer.
• Use pressure surge formulas or install air chambers/pressure relief valves to mitigate.

3. Maintenance Access (Clause 2.2)

• Pipes, valves, and accessories must be easily accessible for inspection, maintenance, and repair.

Quick Design Formula for Water Hammer Pressure Rise:

[ \Delta P = \rho \times a \times \Delta V ]

• (\Delta P): Pressure rise (Pa)
• (\rho): Density of water (≈ 1000 kg/m³)
• (a): Speed of pressure wave (m/s)
• (\Delta V): Change in velocity (m/s)

flowchart LR
    A[Fixtures] --> B[Determine Flow Rate & Units]
    B --> C[Design Piping System]
    C --> D[Check for Water Hammer Pressure]
    D --> E[Provide Access for Maintenance]

Summary: Use Table 1 for flow rates & fixture units, design pipes for water hammer pressure, and ensure easy maintenance access.

IS 12183 Part 1: Water Storage and Supply Systems - Key Points

1. Water Storage Quantity Calculation (Clause 8.1)

• Consider:
  • Hours of supply at adequate pressure to fill tanks/reservoirs.
  • Frequency of replenishment of overhead tanks within 24 hours.
  • Rate and regularity of water supply.
  • Criticality of storage exhaustion, e.g., hospitals need higher reliability.

2. Storage Capacities (Clause 8.4)

• Underground tank capacity = 50% of overhead tank capacity.
• For direct pump/hydro-pneumatic systems (no overhead tank), underground tank = 24 hours water requirement.
• Overhead tank capacity generally covers the demand for several hours, depending on replenishment frequency.

3. Piping Design (Clause 7.7.6)

• Pipes must withstand water hammer pressure (transient pressure surges).

Typical Storage Capacity Formula:

[ V_{OH} = D \times \frac{24}{n} ]

Where:

Summary Table

flowchart TD
    A[Water Demand] --> B[Calculate Daily Requirement]
    B --> C{Storage Type}
    C -->|Overhead Tank| D[Capacity based on refill frequency]
    C -->|Underground Tank| E[50% of Overhead Tank]
    C -->|Direct Pump System| F[24-hour Capacity]
    D --> G[Design Pipes for Water Hammer]
    E --> G
    F --> G

Note: Always refer to local water demand standards and consider building-specific criticality for storage sizing.

IS 12183 Part 1: Pumping Systems and Controls - Key Points

1. Direct Pumping Systems (Clause 6.1.2 & 6.3.2)

• Suitable for buildings with constant water use (e.g., centrally air-conditioned buildings).
• Provide continuous water supply, especially for cooling towers.

2. Pumping System Design (Clause 9.1 & 9.3)

• Pumps must meet peak flow demand.
• System arranged for automatic standby operation:
  • Primary pump runs first.
  • If insufficient, secondary pump starts.
  • One additional standby pump is mandatory.
• In areas with limited power supply hours, increase pumping rate accordingly.
• Emergency power connection recommended where available.

3. Typical Pumping System Arrangement

flowchart LR
    Start --> Pump1[Primary Pump]
    Pump1 -->|Meets Demand| End[System Demand Met]
    Pump1 -->|Fails| Pump2[Secondary Pump]
    Pump2 -->|Meets Demand| End
    Pump2 -->|Fails| Standby[Standby Pump]
    Standby --> End

4. Summary Table (Clause 9.3)

For detailed pump sizing, flow rates, and controls, refer to IS 12183 Part 1 clauses 6 and 9.

IS 12183 Part 1 (1987) — Inspection and Documentation Key Points

Though the code lacks a dedicated clause on Inspection and Documentation, the following essentials apply:

Inspection & Documentation Guidelines (General Practice)

• Record all tests and observations with clear, dated entries.
• Round off values as per IS 2:1960 to maintain consistency.
• Document:
  • Fixture types and quantities.
  • Flow rates and calculated fixture units.
  • Compliance with design flow rates (see Table 1 below).

Table 1: Rate of Flow & Fixture Units (litres/second)

Rounding Off Values (IS 2:1960)

• Round off test results to the same decimal places as specified values.
• Ensures uniformity in documentation.

Summary Diagram: Inspection & Documentation Flow

flowchart TD
    A[Start Inspection] --> B[Record Fixture Types & Quantities]
    B --> C[Measure Flow Rates]
    C --> D[Calculate Fixture Units (Table 1)]
    D --> E[Compare with Design Requirements]