Philippine Plumbing Code: Exam Review Notes (Questions 1–25)

Exam Overview

• Master Plumbing Licensure Exam

  • 100-item multiple–choice test

  • Time allotment: 2 hours

  • Overall weight: 10 % of total board rating

  • Subject breakdown includes “Plumbing Code” (focus of this review)

• Revised National Plumbing Code of the Philippines (NPCP) contains 22 Basic Principles—candidates are expected to memorize and understand all of them.

Key Acronyms & Organizations

• ECC – Environmental Compliance Certificate

  • Government document affirming that a project complies with Philippine environmental regulations.

• ANSI – American National Standards Institute

  • Sets international product, material & safety standards referenced by the NPCP.

• DTI – Department of Trade and Industry

  • Government agency that certifies conformity of plumbing materials to Philippine Product Standards.

• NAAP – National Master Plumbers Association of the Philippines (professional organization)

• PRC Resolution No. 962

  • Issued by the Board of Master Plumbers to adopt & promulgate the 1999 revised NPCP.

Units, Symbols & Conversions

• psi = pounds per square inch; unit of pressure.

• mm/h (millimetres per hour) = rainfall intensity.

• GPH (gallons per hour) = hot-water demand rate.

• Temperature references are in °C.

Selected Basic Principles Cited

• Principle 1 – Pure & wholesome water supply; prevent backflow/back-siphonage.

• Principle 5 – Buildings abutting a street/alley/easement with a public sewer MUST connect to that sewer.

• Principle 10 – Every fixture directly tied to the drainage system needs a water-sealed trap.

• Principle 13 – Entire plumbing system must be tested to disclose leaks & workmanship defects.

• Principle 16 – No water closet in a room lacking proper light & ventilation.

• Principle 20 – Fixtures must be properly spaced to remain accessible.

Question–by–Question Notes (1 - 25)

Q1 – ECC

• Correct answer: Environmental Compliance Certificate (ECC).

• Significance: Required for most building projects; plumbing installations must often show ECC compliance during permitting.

Q2 – Pressure Relief Valve Threshold

• PRV required when system pressure > $80\,\text{psi}$.

• Prevents damage to piping, heaters & fixtures by relieving excess pressure.

Q3 – Inspection Scheduling

• Inspection request must be filed 3 working days before intended date.

• “Administrative Authority” = city/municipal building official or local water district.

Q4 – ANSI

• Provides referenced standards (e.g., ANSI B16 for pipe fittings). Candidates must recognize standard-setting bodies.

Q5 – Conformance Agency for Plumbing Materials

• DTI oversees Philippine Product Standards – ensures faucets, valves, pipes carry correct PS/ICC marks.

Q6 – Hot-Water Demand for Private Hotel Lavatory

• Recommended supply rate: 2 GPH per fixture.

• Used in sizing of water heaters and storage tanks.

Q7 – NAAP

• Professional umbrella organization; liaison with PRC, TESDA, LGUs.

Q8 – Principle 1 Detailed

• Water supply must:

  • Be from a safe source.

  • Remain uncontaminated by cross-connections.

  • Be protected with devices such as double-check valves, air-gaps, vacuum breakers.

Q9 – Principle 5 Detailed

• Mandatory sewer connection eliminates individual septic tanks where a public sewer exists – helps prevent groundwater pollution.

Q10 – Principle 10 Detailed

• Water-seal depth usually $50\;\text{mm}$ (2 in.).

• Prevents sewer gas from entering occupied spaces.

Q11 – Principle 20 Detailed

• Examples of proper spacing:

  • Minimum clearances: WC centerline to side wall $=\,375\;\text{mm}$.

  • Lavatory to adjacent fixture $=\,750\;\text{mm}$ front clearance.

Q12 – Principle 16 Detailed

• Lighting may be natural or artificial; ventilation may be window, louver, or mechanical exhaust.

• Avoids odor build-up and damp conditions conducive to mold.

Q13 – Principle 13 Detailed

• Typical tests:

  • Water test on drainage: 3 m head for 15 min, no drop.

  • Air test on DWV: $38\,\text{kPa}$ (5 psi) for 15 min.

  • Hydrostatic test on water lines: 1.5× working pressure.

Q14 – Rainfall Intensity (Metro Manila)

• Design value: 102 mm/h.

• Used in sizing storm drains, roof leaders, culverts.

Q15 – PRC Resolution Number

• Resolution 962 (1999) – officially enforces the revised NPCP nationwide.

Q16 – Fitting for Vertical-to-Horizontal Transition

• Combination Y & 1/8-bend ("combo Y") only if stack is truly vertical.

• Provides smoother flow with less turbulence compared to 90° elbows.

Q17 – Vent Pipe Sizing Factors

• Determined by:

  • Total developed length (distance from fixture to vent header or roof termination).

  • Number of connected Fixture Units (FU).

  • Longer runs require larger diameter to reduce friction loss & protect trap seals.

Q18 – Shower Curb Elimination

• Allowed when complying with accessibility standards (e.g., BP 344, ADA).

• Produces wheelchair-accessible “roll-in” showers.

Q19 – Cleanout Exemption

• Urinal horizontal drain < 1.5 m need not have cleanout.

• Other fixtures (bathtub, sink) must still comply.

Q20 – Sealing Pipe Sleeves Through Slabs

• Void between pipe & sleeve sealed with bitumen (petroleum-based waterproof mastic).

• Prevents water or gas migration & insect entry.

Q21 – Shower Water Heater Temperature Limit

• Max delivery temperature: 48 – 88 °C.

  • NPCP often recommends $\approx49\,°C$ to prevent scalding.

  • Higher limits accommodate thermostatic mixing valves.

Q22 – Seepage Pit Excavation Depth

• Bottom of excavation must be ≥ 3 m above the water table.

• Prevents direct contamination of groundwater.

Q23 – CES (Chemical or Compact Effluent System) Conditional Use

• Allowed when public sewer will be available in < 2 years (w/ administrative approval).

• Temporary measure for subdivisions or developments awaiting sewer extension.

Q24 – Substitute for Upper-Terminal Cleanout

• Two-way cleanout can replace a straight upper terminal cleanout on building drain/sewer.

• Provides bi-directional rodding access.

Q25 – Siamese Connection Diameter

• Three-way Siamese fire-department connection, standard diameter: 125 mm.

• Facilitates simultaneous hose hookup from three fire trucks/pumpers.

Practical & Ethical Considerations

• Ensuring safe water temperature (≤ 49 °C) protects users from scalds—an ethical duty of the designer.

• Mandated sewer connections & seepage-pit limits protect public health & the environment.

• Proper inspections (3-day filing rule) uphold workmanship quality and code compliance.

Cross-References / Real-World Links

• Pressure relief valve threshold (80 psi) aligns with AWWA recommenda­tions and common residential PRV settings in the U.S.

• Rainfall intensity (102 mm/h) corresponds to PAGASA 5-year return period data for Metro Manila.

• Accessibility shower curb removal mirrors BP 344 (Philippine Accessibility Law) & ADA-ICC A117.1 requirements.

Quick Memory Aids

• “80 psi—Time to PRV”

• “3 Days Notice to Inspect”

• “Principle 10 → Trap 10 (rhymes)”

• “102 mm/h—Manila pours”

• “Resolution 962—NPCP to you”

Exam Overview Questions

Multiple Choice: How many items are on the Master Plumbing Licensure Exam?
a) 50
b) 75
c) 100
d) 120
Answer: c) 100

Fill-in-the-Blank: The Master Plumbing Licensure Exam has a time allotment of 2 hours and accounts for 10 % of the total board rating.

True/False: The Revised National Plumbing Code of the Philippines (NPCP) contains 20 Basic Principles that candidates are expected to memorize.
Answer: False (It contains 22 Basic Principles.)

Key Acronyms & Organizations Questions

Definition: What does ECC stand for and what is its significance?
Answer: ECC stands for Environmental Compliance Certificate. It is a government document affirming that a project complies with Philippine environmental regulations and is required for most building projects.

Matching: Match the organization/resolution with its description:
a) ANSI
b) DTI
c) NAAP
d) PRC Resolution No. 962

i) Government agency that certifies conformity of plumbing materials to Philippine Product Standards.
ii) Sets international product, material & safety standards referenced by the NPCP.
iii) Professional organization for master plumbers.
iv) Issued by the Board of Master Plumbers to adopt & promulgate the 1999 revised NPCP.

Answers:
a) ANSI - ii)
b) DTI - i)
c) NAAP - iii)
d) PRC Resolution No. 962 - iv)

Units, Symbols & Conversions Questions

Symbol Identification: What do the following units and symbols represent?
a) psi
b) mm/h
c) GPH
d) $°C$

Answers:
a) psi = pounds per square inch; unit of pressure.
b) mm/h = millimetres per hour; rainfall intensity.
c) GPH = gallons per hour; hot-water demand rate.
d) $°C$ = Temperature in Celsius.

Selected Basic Principles Questions

Basic Principle Recall: Which Principle states that every fixture directly tied to the drainage system needs a water-sealed trap?
Answer: Principle 10

Basic Principle Application: According to the NPCP, if a building abuts a street with a public sewer, what is the mandatory action regarding drainage?
Answer: The building MUST connect to that public sewer (Principle 5).

Question–by–Question Notes (1 - 25) - Quiz

Q1 – ECC

What is the acronym for "Environmental Compliance Certificate" and why is it required for most building projects?
Answer: The acronym is ECC (Environmental Compliance Certificate). It is required because plumbing installations must often show ECC compliance during permitting.

Q2 – Pressure Relief Valve Threshold

Under what condition is a Pressure Relief Valve (PRV) required in a plumbing system?
a) System pressure < $40\,\text{psi}$ b) System pressure > $80\,\text{psi}$
c) System pressure = $60\,\text{psi}$
d) System pressure = $0\,\text{psi}$
Answer: b) System pressure > $80\,\text{psi}$

Q3 – Inspection Scheduling

How many working days before an intended inspection date must an inspection request be filed?
Answer: 3 working days

Q4 – ANSI

Give an example of a standard provided by ANSI that is referenced in plumbing.
Answer: ANSI B16 for pipe fittings.

Q5 – Conformance Agency for Plumbing Materials

Which government agency oversees Philippine Product Standards and ensures plumbing materials carry correct PS/ICC marks?
Answer: DTI (Department of Trade and Industry)

Q6 – Hot-Water Demand for Private Hotel Lavatory

What is the recommended hot-water supply rate for a private hotel lavatory per fixture?
Answer: 2 GPH (gallons per hour)

Q7 – NAAP

What is the role of NAAP as a "professional umbrella organization"?
Answer: NAAP serves as a liaison with PRC, TESDA, and LGUs (Professional Regulation Commission, Technical Education and Skills Development Authority, and Local Government Units).

Q8 – Principle 1 Detailed

List three ways water supply must be protected according to Principle 1.
Answer: The water supply must: be from a safe source, remain uncontaminated by cross-connections, and be protected with devices such as double-check valves, air-gaps, and vacuum breakers.

Q9 – Principle 5 Detailed

What is the benefit of mandatory public sewer connections as detailed in Principle 5?
Answer: It eliminates individual septic tanks where a public sewer exists, which helps prevent groundwater pollution.

Q10 – Principle 10 Detailed

What is the usual water-seal depth for a trap, and what does it prevent from entering occupied spaces?
Answer: The usual water-seal depth is $50\;\text{mm}$ (2 inches). It prevents sewer gas from entering occupied spaces.

Q11 – Principle 20 Detailed

Give two examples of proper spacing requirements for plumbing fixtures mentioned in Principle 20.
Answer: Examples include: Minimum clearances for WC centerline to side wall $=\,375\;\text{mm}$, and Lavatory to adjacent fixture $=\,750\;\text{mm}$ front clearance.

Q12 – Principle 16 Detailed

What conditions regarding light and ventilation are required for a room containing a water closet?
Answer: Lighting may be natural or artificial; ventilation may be a window, louver, or mechanical exhaust. This avoids odor build-up and damp conditions conducive to mold.

Q13 – Principle 13 Detailed

Describe a typical water test on drainage systems, including the required pressure head and duration.
Answer: A typical water test on drainage involves a $3\,\text{m}$ head for 15 minutes, with no drop allowed.

Q14 – Rainfall Intensity (Metro Manila)

What is the design value for rainfall intensity in Metro Manila, and what is it used for?
Answer: The design value is $102\,\text{mm/h}$. It is used in sizing storm drains, roof leaders, and culverts.

Q15 – PRC Resolution Number

What specific PRC Resolution number officially enforces the revised NPCP nationwide?
Answer: Resolution 962 (1999)

Q16 – Fitting for Vertical-to-Horizontal Transition

Which fitting is recommended for a vertical-to-horizontal transition in a stack to ensure smoother flow and less turbulence?
Answer: Combination Y & 1/8-bend ("combo Y") only if the stack is truly vertical.

Q17 – Vent Pipe Sizing Factors

What two factors determine the sizing of a vent pipe?
Answer: Vent pipe sizing is determined by the total developed length (distance from fixture to vent header or roof termination) and the number of connected Fixture Units (FU).

Q18 – Shower Curb Elimination

Under what conditions is the elimination of a shower curb allowed?
Answer: It is allowed when complying with accessibility standards (e.g., BP 344, ADA), leading to wheelchair-accessible “roll-in” showers.

Q19 – Cleanout Exemption

For which fixture is a horizontal drain of less than $1.5\,\text{m}$ exempted from needing a cleanout?
Answer: Urinal

Q20 – Sealing Pipe Sleeves Through Slabs

What material is used to seal the void between a pipe and its sleeve when passing through slabs?
Answer: Bitumen (petroleum-based waterproof mastic)

Q21 – Shower Water Heater Temperature Limit

What is the NPCP recommended maximum delivery temperature for a shower water heater to prevent scalding?
Answer: The NPCP often recommends $\approx49\,°C$ (within the 48 – 88 °C range) to prevent scalding.

Q22 – Seepage Pit Excavation Depth

How far above the water table must the bottom of a seepage pit excavation be?
Answer: The bottom of the excavation must be $\ge 3\,\text{m}$ above the water table.

Q23 – CES (Chemical or Compact Effluent System) Conditional Use

When is a Chemical or Compact Effluent System (CES) conditionally allowed for use?
Answer: It is allowed when a public sewer will be available in less than 2 years (with administrative approval).

Q24 – Substitute for Upper-Terminal Cleanout

What type of cleanout can replace a straight upper terminal cleanout on a building drain/sewer?
Answer: Two-way cleanout

Q25 – Siamese Connection Diameter

What is the standard diameter for a three-way Siamese fire-department connection?
Answer: 125 mm

Practical & Ethical Considerations Questions

From an ethical standpoint, why is ensuring safe water temperature (e.g., $\le 49\,°C$) important for designers?
Answer: Ensuring safe water temperature protects users from scalds, which is an ethical duty of the designer.

How do mandated sewer connections and seepage pit limits protect public health and the environment?
Answer: Mandated sewer connections and seepage-pit limits help prevent groundwater pollution and protect public health and the environment.

Cross-References / Real-World Links Questions

The pressure relief valve threshold of $80\,\text{psi}$ aligns with recommendations from which organization?
Answer: AWWA (American Water Works Association)

Which Philippine law is mirrored by the allowance for accessibility shower curb removal?
Answer: BP 344 (Philippine Accessibility Law)

Quick Memory Aids Questions

What memory aid is provided for the PRC Resolution number related to the NPCP?
Answer: “Resolution 962—NPCP to you”