The Philippine National Plumbing Code

By the end of this episode, you will be able to answer three main questions. First, what three systems make up a complete plumbing installation? Second, what is the standard slope for horizontal drainage? And finally, which color-coded copper tubing is the thinnest? You are listening to PodThis and Study Session. The National Plumbing Code defines it as the art and technique of installing pipes and fixtures.

We're starting with the core definitions and the legal history of plumbing in the Philippines, which provides the framework for all the technical standards you'll study. To understand the rules, we first have to define what plumbing actually is. It's the system of pipes, drains, fittings, valves, and fixtures used to distribute potable water and remove waterborne waste. Potable water simply means water that's safe for drinking, heating, and washing. The word itself comes from the Latin word plumbum, which means lead. This is because lead was the primary material used for pipes in ancient times. If we look at the National Plumbing Code of 1999, Section 217.6 defines plumbing as the art and technique of installing these pipes and fixtures. It's not just about the hardware; it's about the skill involved in the assembly. Section 217.12 expands on this by listing what the system includes. It covers the potable water supply, the fixtures themselves, traps, and the drainage systems for both sanitary waste and storm water. It also includes the vent pipes that keep the system working and the sewers that carry everything away. You can view the entire plumbing setup as being made of three distinct parts. First, there's the Water Supply and Distribution System. This part carries water from the main source to the various points of use throughout a building. Second, we have the Plumbing Fixtures. These are the receptacles, like sinks or toilets, that receive the water and discharge the waste. Finally, there's the Drainage, Waste, and Vent system, often called the DWV. This is the network of piping that moves waste from the fixtures to a treatment facility or a sewer. The profession has a long history in the Philippines, beginning in the 17th century during the Spanish colonial period. Intramuros served as the model for these early systems. The Friar Engineers of that time followed European standards for their builds. By the 18th and 19th centuries, Filipino plumbers were handling the maintenance and remodeling of these systems. When the 20th century arrived, health and hygiene became a major priority due to various epidemics. This shift happened alongside the arrival of the Americans. In 1902, the role of the master plumber was officially recognized. John F. Hass became the first Chief of the Division of Plumbing Construction and Inspection in Manila. Have you ever wondered when the first professional organization for plumbers began? That happened in 1935, when seventeen master plumbers organized the National Master Plumbers Association of the Philippines, or NAMPAP. The laws we follow today were built on several key milestones. On June 18, 1955, RA 1378, known as the Plumbing Law of the Philippines, was signed into law. This was followed by the promulgation of the National Plumbing Code of the Philippines on January 28, 1959. Later, in 1975, NAMPAP became the 14th professional organization accredited by the PRC. The rules were modernized again. Jaime M. Cabase led the effort to draft the Revised Plumbing Code starting in 1996. The PRC adopted this revised code in December 1999, and it was approved by the President. Today, the Board of Master Plumbing oversees the profession. This board consists of Chairperson Jaime Jajay E. Cruz and members Jason Magos and Samuel M. Paete. This legal structure ensures that every pipe and fixture installed meets a specific standard for public safety.

The National Plumbing Code contains twenty-two basic principles that apply the legal rules we previously discussed to real-world construction. These principles were updated and revised on December 21, 1999. Every building intended for human habitation must have a reliable water supply. This supply needs to provide enough pressure and volume to keep the fixtures working properly. The code also says you should use the minimal amount of supply possible. Safety is a major priority, particularly regarding how we heat water. Any system that heats water must be designed to prevent an explosion. When it comes to waste, any building meant for people to live in must connect to a public sewer. If there is no public sewer nearby, you are required to use a septic tank or a treatment system. For a private sewage unit to be sufficient, it must include at least one water closet and one kitchen sink. The physical quality of the fixtures matters just as much as the pipes. Every fixture must be made of smooth, non-absorbent material so it stays sanitary. To keep the air inside a building safe, each fixture needs a water-sealed trap. A trap is a fitting that holds a small pool of water to block sewer gases from coming into the room. These traps require adequate air circulation to prevent siphonage. Siphonage is when air pressure pulls the water seal out of the trap. This is why the code mandates vent terminals that lead to the outer air. The 1999 revision that established these principles was overseen by the Members of the Board. This group included Chairperson Jaime Jajay E. Cruz. It also included Jason Magos and Samuel M. Paete. Durability is another core requirement for every part of the system. You must use materials that are lasting and perform your work with high-quality craftsmanship. The drainage design should prevent clogging and must include a cleanout for maintenance. A cleanout is a specific fitting with a removable plug that allows you to clear a clog without cutting the pipe. You cannot allow any substances into the system that might explode, destroy the pipes, or cause a blockage. To protect food from contamination, the system must include an air break. An air break is a physical separation between a waste pipe and the drain it flows into. This gap prevents waste from backing up into food preparation areas. Every water closet requires proper ventilation to keep the air fresh. The system must also be designed to prevent fixtures from overflowing and causing water damage. Once a project is finished, the plumbing must be tested to prove it is watertight and gas-tight. This testing ensures that every joint and connection is secure before the system is used. Even after the building is occupied, you must maintain the system in a serviceable condition. The code also requires that fixtures are properly spaced so they are easy to use and clean. During installation, you must be careful to preserve the structural strength of the building. No harmful waste can be discharged into the ground. These rules ensure that plumbing remains a science of health and safety for the entire community. Question. What law is known as the Plumbing Law of the Philippines and when was it signed? Answer. RA 1378 is known as the Plumbing Law of the Philippines and it was signed on June 18, 1955.

Drainage piping grade and direction changes apply the general rules of waste removal to the specific geometry of a building's pipe network. The grade of a pipe refers to its downward slope. A uniform slope means the pipe maintains the exact same angle throughout its horizontal run toward the disposal point. The National Plumbing Code requires a minimum slope of 20 millimeters per meter for horizontal drainage. This is equivalent to a 2 percent grade. This specific angle ensures that water flows with enough speed to carry waste solids along with it. Sometimes a 2 percent slope is not possible due to the depth of the building or the shape of the local terrain. The code refers to these difficult situations as impracticable. If a 2 percent slope is truly impracticable, there's an exception for larger pipes. Pipes with a diameter of 102 millimeters or greater may use a slope of 10 millimeters per meter. This is a 1 percent grade. If the environment prevents even a 1 percent slope, you must use a Vacuum Foul Sewer System as an alternative method for moving waste. Changes in the direction of drainage flow are also strictly controlled to prevent clogs. You're permitted to use specific angles for these turns. These angles include 22 and a half degrees, 45 degrees, and 60 degrees. You may also use longer sweeps. A sweep is a fitting designed with a gradual curve to allow for a smoother transition of water and waste. When you move from a horizontal pipe to a vertical one, you must use specific fittings to manage the change. These include a 45-degree wye, a 60-degree wye, or a combination wye and one-eighth bend. A wye is a fitting that connects two pipes at an angle. A combination wye and one-eighth bend is a single fitting that joins a 45-degree wye with an additional curve to create a very smooth path. A sanitary tee is another option for this transition. It's a fitting with a slight internal curve that helps direct horizontal flow downward into a vertical stack. There's a specific rule for using double sanitary tees. A double sanitary tee allows two horizontal pipes to enter a single vertical pipe from opposite sides. The barrel is the main vertical section of this fitting. The code requires the barrel to be two pipe sizes larger than the largest side inlet. This extra space prevents waste from one inlet from shooting across and interfering with the flow of the other. The standard pipe sizes used for these calculations are 2 inches, 2 and a half inches, 3 inches, and 3 and a half inches. The list continues with 4 inches, 4 and a half inches, 5 inches, and 6 inches. If your largest side inlet is 2 inches, you look at this list and move two sizes up. One size up from 2 inches is 2 and a half, and the second size up is 3 inches. Therefore, a double sanitary tee with a 2-inch inlet must have a 3-inch barrel. Following these specific sizing and grading rules ensures that the system remains self-cleaning and functional. Question. According to the 22 basic principles, what is required for human habitation regarding waste disposal? Answer. A connection to a public sewer is required.

Supporting the physical weight of a plumbing system ensures that the precise slopes and angles of your pipes remain stable over time. Every hanger or anchor you use must be strong enough to hold the weight of the pipe itself. It must also support the weight of the water or waste flowing inside. Vertical plastic pipes require supports at one-meter intervals. An interval is simply the distance between two points where the pipe is held up. For horizontal cast iron pipes, you need to place a support every one point five meters. If a single pipe section is longer than one point five meters, the maximum distance between hangers can be three meters. You must also place a support within zero point four five meters of every hub or joint. This prevents the connections from sagging or leaking. Screwed pipes have different requirements based on their size. For pipes nineteen millimeters and smaller, you space hangers at three-meter intervals. For larger pipes of twenty-five millimeters or more, the spacing increases to three point six meters. Copper tubing also needs regular support. You should place hangers every storey or at three-meter intervals for vertical copper lines. Copper tubing is categorized by its wall thickness. It's identified by a color-coded system so you can choose the right material for the job. Type K uses green markings. It's the thickest variety and is designed for underground burial or use under streets. Type L is blue. It's thinner than Type K and is commonly used for residential or commercial water supply. Type M uses red markings and is even thinner than Type L. The thinnest type is DWV, marked in yellow or orange. DWV stands for Drain, Waste, and Vent. This type is only for unpressurized systems. Hard drawn copper is significantly stronger than annealed copper. It has one hundred and fifty percent more tensile strength. When you use lead for safe pans, the material must weigh nineteen point five six kilograms per square meter. Lead flashing used for vent terminals is slightly lighter at fourteen point six three kilograms per square meter. Fittings must also meet specific quality standards. Caulking ferrules are sleeves used for joining pipes. They must be made of red cast brass, bronze, or copper. Closet rings, also called closet flanges, connect a water closet to the drainage system. These are one hundred and seventy-eight millimeters in diameter. Each ring requires four bolts to secure the fixture properly. Gate valves are used to completely stop or allow the flow of water. If a gate valve is smaller than one hundred and two millimeters, it should be made of cast brass or bronze. For larger sizes, the bodies are typically made of cast iron. Trenching for pipes requires specific safety measures to protect the materials. If you dig a tunnel for a pipe, it must be at least zero point six meters above the pipe. The maximum length for these tunnels is two point four meters. This length should be no more than half the depth of the overall trench. When pipes pass through walls, you must use metal pipe sleeves to protect them from damage. Question. What is the minimum uniform slope required for horizontal drainage piping? Answer. Horizontal drainage piping requires a uniform slope of not less than 20mm/m, which is a 2% grade toward the point of disposal.

Traps and interceptors are the final line of defense for your plumbing. They build on the material standards we already covered for pipes and hangers. A trap is a fitting that creates a liquid seal. This water seal is the liquid held between the overflow and the dip of the trap. It acts as a physical barrier to keep sewer gases out of your living space. There are two main categories for these seals depending on how deep they are. A Common Seal is five centimeters deep. If a system needs more protection, you use a Deep Seal. Those measure between seven point five and ten centimeters deep. The general rule in the code is that a trap cannot be larger than the fixture outlet it serves. Most of the time, you need one trap for every fixture arm. But there are exceptions where a single trap can handle multiple fixtures. You might use one trap for two laundry trays and a kitchen sink, or even for three separate lavatories. To keep these traps working, you have to protect the vent. The developed length of a trap arm must be at least twice its own diameter. This spacing makes sure air flows properly without pulling the water out of the trap. For a water closet, the maximum length of the trap arm is one point eight meters from the closet ring to the vent. The distance from the fixture outlet to the trap weir also has a limit. This is called the tail piece. It can be no longer than zero point six meters. If you change the direction of a trap arm smaller than seventy-six millimeters, you are limited to a ninety-degree turn unless you add a cleanout. For larger arms of seventy-five millimeters or more, you need a cleanout if the change in direction is more than twenty-two and a half degrees. A trap can lose its protective water seal in four main ways. The first is Trap Siphonage, which is caused by negative pressure in the pipes. The second is Back Pressure, which is the opposite effect. The third is simple Evaporation. This usually happens in fixtures that are not used very often. The final way is Capillary action. This happens when a foreign object, like a piece of string, acts as a wick to pull water over the edge of the trap. In some cases, you will need a Drum Trap. These are used for floor fixtures like bathtubs because they handle high water discharge effectively. Some systems also require specialized traps called interceptors or clarifiers. Industrial interceptors must have a seal of at least one hundred and fifty-two millimeters. For sand interceptors, the code requires an opening of at least zero point two square meters and a depth of six hundred and ten millimeters below the outlet pipe. To prevent contamination, the code requires an air gap for direct connections. This is a vertical distance through the open air that prevents backflow. This gap must be at least two pipe diameters high, with a minimum distance of twenty-five millimeters. Finally, we have backwater valves. These stay open during low flow but must not restrict the system during peak loads. They provide one more layer of protection for the drainage network. Question. Which color-coded type of copper tubing is the thickest and used for underground burial? Answer. The thickest type of copper tubing is Type K, which is color-coded green.

We're starting the recap quiz now. Try to answer each question in your head before you hear the answer. Question. What specific law is recognized as the Plumbing Law of the Philippines? Answer. RA 1378 is known as the Plumbing Law of the Philippines. Question. According to the twenty-two basic principles, what must be installed on fixtures to prevent sewer gas from entering the building? Answer. Every fixture must be equipped with a water sealed trap. Question. If a standard two percent slope is impracticable, what slope is allowed for drainage pipes that are 102 millimeters or larger? Answer. Pipes of this size may have a slope of 10mm/m, which is a 1% grade. Question. At what intervals must vertical plastic piping be supported? Answer. Vertical plastic pipes require support at 1m intervals. Question. What is the minimum required developed length for a trap arm in relation to the diameter of the pipe? Answer. The trap arm must have a developed length that is at least twice the diameter of the pipe.

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