{"id":37583,"date":"2022-11-07T16:14:13","date_gmt":"2022-11-07T08:14:13","guid":{"rendered":"https:\/\/3t-insulation.com\/plumbing-system-design\/"},"modified":"2026-01-27T13:16:49","modified_gmt":"2026-01-27T05:16:49","slug":"plumbing-system-design","status":"publish","type":"post","link":"https:\/\/3t-insulation.com\/en\/plumbing-system-design\/","title":{"rendered":"Plumbing System Design"},"content":{"rendered":"

Plumbing System Design<\/h1><\/div><\/div><\/div>

<\/i><\/i><\/span>Read more<\/span><\/a><\/h4><\/div>
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<\/div><\/div>\n<\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div>

Key Considerations in Plumbing System Design<\/h3><\/div>
    \n
  1. Water Quality and Quantity<\/li>\n<\/ol>\n

    Water supplied to buildings must be of suitable quality for consumption and use, with sufficient quantity for operational needs.<\/p>\n

      \n
    1. Pipe Materials<\/li>\n<\/ol>\n

      Plumbing pipe materials are standardized for water distribution. Building plumbing typically uses Galvanized Steel Pipe, Black Steel Pipe, Copper Pipe, Cast Iron Pipe, or Plastic Pipe (PE, PVC).<\/p>\n

        \n
      1. Building Plumbing System<\/li>\n<\/ol>\n

        As a principle, pipes should be installed in straight lines to achieve the shortest distance (for cost efficiency).<\/p>\n<\/div>

        \"Plumbing<\/span>
        <\/div>

        Plumbing System for Buildings up to 3 Floors<\/p><\/div><\/div><\/div>

        \"Plumbing<\/span>
        <\/div>

        Plumbing System for Buildings up to 10 Floors<\/p><\/div><\/div><\/div>

        Types of Building Water Distribution Systems<\/h3><\/div>

        Building water distribution systems can be divided into 2 types based on design:<\/p>\n

          \n
        1. Upfeed System<\/li>\n<\/ol>\n

          The upfeed system distributes water upward through the building height, suitable for buildings up to 10 floors and less than 10,000 square meters.<\/p>\n<\/div>

          \"Upfeed<\/span>
          <\/div>

          Upfeed System<\/p><\/div><\/div><\/div>

            \n
          1. Downfeed System<\/li>\n<\/ol>\n

            The downfeed system distributes water downward from the top floor, suitable for tall buildings and large buildings.<\/p>\n<\/div>

            \"Downfeed<\/span>
            <\/div>

            Downfeed System<\/p><\/div><\/div><\/div>

            Water distribution in high-rise buildings can be divided into multiple zones for easier maintenance and pressure management.<\/p>\n<\/div>

            \"Downfeed<\/span>
            <\/div>

            Downfeed System with Multiple High Tanks<\/p><\/div><\/div><\/div>

            In downfeed systems with rooftop water tanks, plumbing fixtures and water-using equipment on upper floors may have insufficient water pressure and volume. Therefore, the upper floor water system is separated and a “pressure tank” is added to increase pressure and water volume for adequate usage.<\/p>\n<\/div>

            \"Plumbing<\/span>
            <\/div>

            Combined System<\/p><\/div><\/div><\/div>

            Water Hammer<\/h3><\/div>

            Water hammer occurs when flowing water is suddenly blocked (by closing valves or faucets). When water cannot continue flowing, it creates impact and backflow, causing pipe vibration, noise, and accelerated pipe damage.<\/p>\n

            Water hammer pressure can be calculated using the formula:<\/p>\n

            P = 14.8V<\/p>\n

            Where:<\/p>\n

            P = Pressure increase from water hammer (unit: bar)<\/p>\n

            V = Water velocity (unit: meters\/second)<\/p>\n

            We can see that internal pipe pressure increases 4-8 times normal operating pressure.<\/p>\n<\/div>

            \"Water<\/span>
            <\/div>

            Water Hammer<\/p><\/div><\/div><\/div>

            Water Hammer Prevention<\/h3><\/div>

            We can prevent water hammer by installing devices that “absorb pressure wave energy” (water hammer arrestor) in the pipe system. The simplest device is called an Air Chamber, which is a water pipe extended beyond the fixture connection.<\/p>\n<\/div>

            \"Air<\/a><\/span>
            <\/div>

            Air Chamber (from dongilmt.com)<\/p><\/div><\/div><\/div>

            \"Water<\/span>
            <\/div>

            Using Air Chambers for Multiple Fixtures<\/p><\/div><\/div><\/div>

            Flow Rate and Pressure Requirements for Plumbing Fixtures<\/h3><\/div>

            Each type of plumbing fixture requires specific pressure and flow rates as recommended by manufacturers. Minimum pressure and flow rates for common fixtures can be found in the table below.<\/p>\n<\/div>\n

            \n

            Table showing pressure and flow rates for common plumbing fixtures<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
            \n

            Plumbing Fixtures<\/p>\n<\/th>\n

            		\n

            Pressure
            bar (psi)<\/p>\n<\/th>\n

            		\n

            Flow Rate
            Lps (gpm)<\/p>\n<\/th>\n<\/tr>\n<\/thead>\n

            Ordinary basin faucet<\/td>\n\n

            0.55 (8)<\/p>\n<\/td>\n

            		\n

            0.19 (3)<\/p>\n<\/td>\n<\/tr>\n

            Self-closing basin faucet<\/td>\n\n

            0.84 (12)<\/p>\n<\/td>\n

            		\n

            0.16 (2.5)<\/p>\n<\/td>\n<\/tr>\n

            Sink faucet (15 mm.)<\/td>\n\n

            0.35 (5)<\/p>\n<\/td>\n

            		\n

            0.28 (4.5)<\/p>\n<\/td>\n<\/tr>\n

            Bathtub faucet<\/td>\n\n

            0.35 (5) <\/span><\/p>\n<\/td>\n

            		\n

            0.38 (6)<\/p>\n<\/td>\n<\/tr>\n

            Laundry tub cock<\/td>\n\n

            0.35 (5)<\/p>\n<\/td>\n

            		\n

            0.32 (5)<\/p>\n<\/td>\n<\/tr>\n

            Shower<\/td>\n\n

            0.84 (12)<\/p>\n<\/td>\n

            		\n

            0.32 (5)<\/p>\n<\/td>\n<\/tr>\n

            Ball cock for closet<\/td>\n\n

            1.00 (15)<\/p>\n<\/td>\n

            		\n

            0.19 (3)<\/p>\n<\/td>\n<\/tr>\n

            Flush valve for closet<\/td>\n0.7-1.4 (10-20)<\/td>\n\n

            0.9 – 2.5 (15 – 40)<\/p>\n<\/td>\n<\/tr>\n

            Flush valve for urinal<\/td>\n\n

            1.00 (15)<\/p>\n<\/td>\n

            		\n

            0.95 (15)<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

            Due to varying pipe pressure, installing flow control devices for fixtures provides these benefits:<\/p>\n

              \n
            1. Can limit necessary flow rates for each type of fixture<\/li>\n
            2. Enables more precise pipe design<\/li>\n
            3. Saves energy in the water system<\/li>\n<\/ol>\n<\/div>
              \"Flexible<\/a><\/span>
              <\/div>

              Flexible Orifice (image from bertfelt.com)\n<\/p><\/div><\/div><\/div>

              Daily Water Demand<\/h3><\/div>

              Different types of buildings have varying daily water demands, typically ranging from 75-300 liters (20-80 gallons). Daily water demand for buildings can be found in the table below.<\/p>\n<\/div>\n

              \n\n\n\n\n\n\n\n\n\n\n\n\n
              Building Type<\/th>\nWater Demand
              Liters\/Person\/Day<\/th>\n<\/tr>\n<\/thead>\n
              Residential Buildings\/Apartments<\/td>\n\n

              100 – 300<\/p>\n<\/td>\n<\/tr>\n

              Office Buildings<\/td>\n\n

              40 – 70<\/p>\n<\/td>\n<\/tr>\n

              Hospitals<\/td>\n\n

              600 – 1200<\/p>\n<\/td>\n<\/tr>\n

              Schools<\/td>\n\n

              50 – 80<\/p>\n<\/td>\n<\/tr>\n

              Hotels<\/td>\n\n

              200 – 400<\/p>\n<\/td>\n<\/tr>\n

              Dormitories<\/td>\n\n

              200 – 300<\/p>\n<\/td>\n<\/tr>\n

              Laundries<\/td>\n\n

              20 – 40<\/p>\n<\/td>\n<\/tr>\n

              Airports<\/td>\n\n

              15 – 25<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

              Pipe Sizes for Plumbing Fixtures<\/h3><\/div>

              Plumbing pipe sizes for different fixtures are specified to ensure adequate water supply and appropriate pressure, as shown in the table below.<\/p>\n<\/div>\n

              \n

              Table showing minimum pipe sizes for each type of fixture<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
              \n

              Type of Fixture<\/p>\n<\/th>\n

              		\n

              Pipe Size mm. (inches) <\/p>\n<\/th>\n<\/tr>\n<\/thead>\n

              Bathtub<\/td>\n\n

              15 (1\/2)<\/p>\n<\/td>\n<\/tr>\n

              Drinking fountain<\/td>\n\n

              10 (3\/8)<\/p>\n<\/td>\n<\/tr>\n

              Dishwasher<\/td>\n\n

              15 (1\/2)<\/p>\n<\/td>\n<\/tr>\n

              Lavatory<\/td>\n\n

              15 (1\/2)<\/p>\n<\/td>\n<\/tr>\n

              Shower<\/td>\n\n

              15 (1\/2)<\/p>\n<\/td>\n<\/tr>\n

              Urinal with angle valve<\/td>\n\n

              15 (1\/2)<\/p>\n<\/td>\n<\/tr>\n

              Urinal with flush valve<\/td>\n\n

              20 (3\/4)<\/p>\n<\/td>\n<\/tr>\n

              Water closet with flush tank<\/td>\n\n

              15 (1\/2)<\/p>\n<\/td>\n<\/tr>\n

              Water closet with flush valve<\/td>\n\n

              25 (1)<\/p>\n<\/td>\n<\/tr>\n

              Hose bib<\/td>\n\n

              15 (1\/2)<\/p>\n<\/td>\n<\/tr>\n

              Service sink<\/td>\n\n

              20 (3\/4)<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

              Maximum Water Demand Estimation<\/h3><\/div>

              In pipe system design, we must consider:<\/p>\n