Water supply systems are fundamental to all professional environments across Kenya, from hospitals and universities to banks and agricultural cooperatives. Accurate and clear plumbing drawings are essential in planning, installing, and maintaining these systems efficiently. This chapter focuses on developing skills to sketch simple plumbing drawings and interpret standard symbols, enabling students to communicate technical information effectively across diverse sectors.

2.1 Working drawings

Working drawings are detailed plans that guide the construction and maintenance of water supply systems. In Kenyan workplaces such as county referral hospitals, retail businesses, and government offices, these drawings ensure that plumbing installations meet safety, functionality, and regulatory standards. Different types of working drawings include pictorial, line drawings, and freehand sketches, each serving distinct purposes in design communication and documentation.

2.1.1 Pictorial drawings

Pictorial drawings present plumbing systems in a three-dimensional view, offering a realistic representation that is easy to understand by both technical and non-technical personnel. These drawings are especially useful in contexts like hotel maintenance departments and school facility management, where visual clarity facilitates decision-making.

Purpose of pictorial drawings

• Visual comprehension: They help stakeholders visualize the plumbing layout, reducing misunderstandings during installation.
• Client presentations: Useful in explaining designs to clients or non-technical managers in county government offices.
• Coordination: Facilitate coordination among different trades such as electricians and plumbers in university construction projects.
• Troubleshooting: Assist maintenance teams in retail businesses to identify and locate system components quickly.
• Training: Serve as educational tools for new technicians in cooperative water projects.

Characteristics of pictorial drawings

• Three-dimensional view: Displays height, width, and depth, providing a realistic perspective.
• Detailed components: Shows fixtures, pipes, valves, and fittings clearly.
• Scale representation: Usually drawn to scale but can be simplified for clarity.
• Color coding: Often uses colors to differentiate pipe types or flow directions.
• Annotation: Includes labels and notes for easy identification of parts.

Types of pictorial drawings used in plumbing

• Isometric drawings: Show the system at equal angles, maintaining scale and proportion.
• Oblique drawings: Emphasize the front face with receding lines drawn at an angle.
• Perspective drawings: Mimic human eye view, showing depth realistically but less commonly used in technical plumbing.

Steps to construct an isometric pictorial drawing

1. Identify the plumbing components: List all pipes, valves, and fixtures to be included.
2. Draw the isometric axes: Sketch three lines at 120 degrees from a point to represent height, width, and depth.
3. Plot the main pipes: Draw straight lines along the axes to represent pipes.
4. Add fittings and fixtures: Insert valves, taps, and other components at appropriate locations.
5. Include flow direction: Use arrows to indicate water flow.
6. Label components: Annotate each part with standard symbols and notes.

2.1.2 Line drawings

Line drawings are two-dimensional representations that use lines, symbols, and annotations to convey plumbing system details. In Kenyan banks and SACCOs, line drawings are essential for documenting water supply layouts in building plans, ensuring compliance with health and safety regulations.

Meaning and significance of line drawings

• Meaning: They are simplified technical drawings using lines to represent pipes and fixtures without three-dimensional perspective.
• Significance: Enable precise measurement and layout planning, essential for contractors and inspectors in county government offices.

Types of lines used in plumbing drawings

Common plumbing symbols used in construction/engineering drawings (Source: install_water_supply_syst (1))

• Continuous thick lines: Represent visible pipes and fittings.
• Dashed lines: Indicate hidden or underground pipes.
• Chain lines: Show centerlines of pipes or equipment.
• Thin lines: Used for dimensioning and annotations.
• Dot-dash lines: Represent insulation or special pipe coatings.

Standard symbols used in line plumbing drawings

• Tap/faucet: Symbolized by a circle with a line.

• Valve: Depicted as a bow-tie or diamond shape.

• Pump: Represented by a circle with a ‘P’ inside.

• Pipe junction: Shown by intersecting lines with dots.

• Drainage: Illustrated with a downward arrow and pipe line.

Procedure to create a plumbing line drawing

1. Gather system specifications: Obtain all necessary measurements and component details.
2. Draw the floor plan outline: Sketch the building or area layout to scale.
3. Plot the main water supply lines: Use continuous thick lines to indicate pipes.
4. Insert plumbing fixtures: Mark taps, valves, and pumps with standard symbols.
5. Add dimension lines: Indicate pipe lengths and distances between fixtures.
6. Annotate the drawing: Include notes on materials, flow direction, and pipe sizes.

2.1.3 Freehand sketching Scale drawings

Freehand sketching is a quick and informal method to capture plumbing ideas or modifications on-site. This skill is crucial for technicians and facility managers in agricultural cooperatives and hospitals who need to communicate changes or problems without formal drawing tools.

Importance of freehand sketches in water supply systems

• Speed: Allows rapid documentation of plumbing issues or proposals.
• Flexibility: Can be done anywhere without specialized equipment.
• Communication: Facilitates on-the-spot discussions among technicians and supervisors at retail business sites.
• Problem-solving: Helps identify faults or plan repairs in county government offices.
• Record-keeping: Provides a visual reference for future maintenance.

Characteristics of effective freehand sketches

• Clarity: Clear lines and symbols to avoid confusion.
• Proportion: Reasonably accurate sizes and spatial relationships.
• Labeling: Proper annotation of components and flow directions.
• Simplicity: Focus on key details without unnecessary complexity.
• Neatness: Legible and organized to aid interpretation.

Tools commonly used for freehand sketching

• Keep pencils sharpened for precision.
• Use erasers gently to avoid tearing paper.
• Rulers ensure straight lines for pipe representation.
• Colored pens distinguish different pipe types or flow directions.
• Maintain a dedicated sketch notebook for systematic records.

Steps to produce a freehand plumbing sketch on-site

1. Observe the plumbing system: Note the layout and components present.
2. Sketch the general layout: Draw the area outline including walls and major features.
3. Add main pipes and connections: Represent pipes with simple lines.
4. Include fixtures and valves: Mark with basic symbols or labels.
5. Indicate flow direction: Use arrows to show water movement.
6. Annotate with notes: Add brief descriptions or measurements as needed.

Chapter Summary

This chapter introduced various types of working drawings essential for plumbing design, including pictorial, line, freehand sketching, and scale drawings, each serving specific purposes in communication and accuracy. The differences between these drawing styles were highlighted to show their relevance in planning and executing plumbing installations. Interpretation of working pipework drawings was emphasized to enable accurate reading and understanding of plumbing layouts and connections. The chapter also covered measurements and symbols used in plumbing drawings, focusing on isometric pipework drawings which provide a three-dimensional view for clarity. Students learned how to interpret these working drawings effectively to ensure proper implementation on site. Overall, the chapter built foundational skills in sketching and understanding plumbing drawings necessary for successful water supply system design and maintenance.