2.1 Demanddesign Water Supply System

A water supply system is analogous to the human circulatory system. The heart pumps blood through the arteries, veins, and capillaries to supply oxygen to all part of the body. A water pump supplies water through primary, secondary, and distributor water mains to supply water to consumers and for fire. Acknowledgments This is the fourth edition of the Water System Design Manual.Many Department of Health (DOH) employees provided valuable insights and suggestions to this publication.

• Demand Supply And Price
• 2.1 Demanddesign Water Supply System
• 2.1 Demanddesign Water Supply Systems
• Example Of Supply And Demand

WSFU is used to calculate water supply service systems

The design process of the CWQM system is a multi-objective task that requires informed decision-making, using optimisation tools and making various assumptions for different objectives. Water utilities must weigh the costs and benefits of various designs and understand the significant public-health and cost trade-offs. DWSS - Part 2 Ch1 – Water Demand Ch1 - 1/14 Chapter 1. Water Demand What you will learn Estimate the different information needed to define precisely the water demand of a community. Why This will give the term of reference for the complete Water Supply System, make it working or not, sustainable or not. Duration of chapter 1.

The WSFU (Water Supply Fixture Units) is defined by the Uniform Plumbing Code (UPC) and can be used to determine water supply to fixtures and their service systems.

• 1 WSFU = 1 GPM = 3.79 liter/min
• 1 in = 25.4 mm

Note that this conversion is only true for one or a few fixtures. Since all fixtures in a system are never used at the same time, the total units achieved by adding the numbers for all fixtures must be compensated for their intermittent use.

For supply pipe lines this is taken care of in the sizing tables.

For manifolds or special equipments sizing, a formula or a table can be used.

Related Topics

• Water Systems - Hot and cold water service systems - design properties, capacities, sizing and more

Related Documents

• Cold Water Storage Capacity - Required cold water storage capacity - commonly used fixtures and types of buildings
• Cold Water Storage per Occupant - Cold water storage for occupants in common types of buildings as factories, hospitals, houses and more
• Cross-Contamination Control - It is fundamental to keep the potable water in the water supply systems uncontaminated
• Domestic Hot Water Service Systems - Design Procedure - Design procedure for domestic hot water service systems
• Drainage Fixture Unit Values - DFU - DFU are used to determine the drainage from fixtures and required capacity of sewer service systems
• Drainage Fixtures - Unit Loads and Sanitary Piping - Maximum Drainage Fixture Unit - DFU - loads for sanitary piping
• Drains and Sewers - Drainage Fixture Units (DFU) connected to building drains and sewers
• Farm Livestock - Water Consumption - Farming and animal required water supply
• Fixture Units - WSFU vs GPM and Liters/sec - Converting WSFU - Water Supply Fixture Units - to GPM
• Hoses - Water Flow and Pressure Losses - Water flow and pressure loss due to friction in hoses
• Hot and Cold Water Pipe Sizing - Recommended dimensions of hot and cold water pipes
• Hot Water Circulation Return Pipe - Hot water can be circulated through a return pipe if it's instantly required at the fixtures
• Hot Water Consumption per Occupant - Consumption of hot water per person or occupant
• Hot Water Content in Fixtures - Content of hot water in some common used fixtures - basins, sinks and baths
• Main Vents in Draining Systems - Vents in draining systems protects traps against pressure differences that could cause them to siphon or blow out
• Online Design of Water Supply Systems - Online design tool for a water supply system
• PE Water Supply Pipes - Properties - Nominal pipe size, outside diameter, wall thickness, weight and working pressure
• Plumbing Codes - Plumbing or sanitation codes are a set of rules and regulations imposed by cities, counties or states
• Sizing Water Supply Lines - Sizing water supply service and distribution lines based on Water Supply Fixture Units (WSFU)
• Water Distribution Pipes - Materials used in water distribution pipes
• Water Supply - Calculating Demand - Calculating expected demand of water supply in service lines
• Water Supply Pipe Lines - Sizing - Sizing of water supply pipe lines
• Water Supply to Public Buildings - Required water supply to public buildings
• Yard Fixtures - Water Consumption - Water consumption in garden fixtures

Calculating expected demand of water supply in service lines

Demand Supply And Price

The total theoretical demand for a water supply system can easily be calculated by adding known maximum demand for all fixtures in the system. Due to the nature of intermittent use this will unfortunate add up to unrealistic demands for the main supply service lines. A realistic demand for a supply system will always be far less than the total theoretical demand.

Expected demand in a water supply system can be estimated as

q_et = q_nl + 0.015 ( Σq_n - q_nl ) + 0.17 ( Σq_n - q_nl )^1/2 (1)

where

q_et = expected total water flow (l/s)

q_nl = demand of largest consumer (l/s)

Σq_n = total theoretical water flow - all fixtures summarized (l/s)

Note that minimum expected total water flow can never be less than the demand from the largest fixture. This equation is valid for ordinary systems with consumption patterns like

• homes
• offices
• nursing homes
• etc.

Be aware when using the equation for systems serving large groups of people where the use is intermittent, like in

• hotels
• hospitals
• schools
• theaters
• wardrobes in factories
• etc

For these kind of applications, like a wardrobe, it is likely that all showers are used at the same time. Using the formula blindly would result in insufficient supply lines.

Example - Main Water Supply to a Nursing Home

If the theoretical demand from all fixtures in a nursing home adds up to 50 l/s and the larges fixture requires 0.4 l/s, the expected water supply demand can be estimated like

q_et = (0.4 l/s) + 0.015 ((50 l/s) - (0.4 l/s)) + 0.17 ((50 l/s) - (0.4 l/s))^1/2

= 2.3 (l/s)

Total Theoretical Water Flow and Expected Flow

2.1 Demanddesign Water Supply System

Expected demand for a supply system at different total theoretical demand can based on the formula above be expressed as

The maximum fixture load is 0.2 liter/s.

Related Topics

• Water Systems - Hot and cold water service systems - design properties, capacities, sizing and more

Related Documents

• Cross-Contamination Control - It is fundamental to keep the potable water in the water supply systems uncontaminated
• Domestic Hot Water Service Systems - Design Procedure - Design procedure for domestic hot water service systems
• Fixture Units - WSFU vs GPM and Liters/sec - Converting WSFU - Water Supply Fixture Units - to GPM
• Fixture Water Requirements - Water outlets demand
• Online Design of Water Supply Systems - Online design tool for a water supply system
• PE Water Supply Pipes - Properties - Nominal pipe size, outside diameter, wall thickness, weight and working pressure
• Sizing Water Supply Lines - Sizing water supply service and distribution lines based on Water Supply Fixture Units (WSFU)
• Water - Human Activity and Consumption - Activity and average water consumption
• Water Distribution Pipes - Materials used in water distribution pipes
• Water Service Pipe Lines - Water service pipe lines extends from the potable water source to the interior of buildings
• Water Supply - Fixture Units WSFU - WSFU is used to calculate water supply service systems
• Water Supply Pipe Lines - Sizing - Sizing of water supply pipe lines
• Water Supply to Public Buildings - Required water supply to public buildings

2.1 Demanddesign Water Supply Systems

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