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100+ Free Sanitary Engineer Licensure Exam Practice Questions
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2026 Statistics
Key Facts: Sanitary Engineer Licensure Exam Exam
6
Board Subjects
PRC Board of Sanitary Engineering
70%
Passing Average
PRC
50%
Minimum Per Subject
PRC
270
Jan 2026 Examinees
PRC
CBLE
Computer-Based
PRC 2026
RA 1364
Governing Law
Sanitary Engineering Law
The Sanitary Engineer Licensure Examination (SELE) is the PRC objective board exam for registration under RA 1364, now delivered as a computer-based licensure examination (CBLE). Candidates must obtain a 70% weighted general average with no grade below 50%. The January 2026 CBLE had 270 examinees with results released immediately after testing. Coverage spans six subjects: Water Supply, Wastewater and Urban Drainage, Environmental Engineering, Sanitary Science as Applied to Buildings, Public Health Engineering, and allied Civil Engineering, with about a 70% objective and 30% problem-solving split.
Sample Sanitary Engineer Licensure Exam Practice Questions
Try these sample questions to test your Sanitary Engineer Licensure Exam exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1In the conventional water treatment train, chemical coagulants such as alum are added during which unit process to destabilize colloidal particles?
A.Slow flocculation
B.Rapid mixing (coagulation)
C.Sedimentation
D.Disinfection
Explanation: Coagulant chemicals like aluminum sulfate (alum) are introduced and dispersed during rapid mixing so the resulting metal hydroxides neutralize the negative surface charge of colloids, allowing them to agglomerate. This destabilization step must occur before gentle flocculation builds settleable floc.
2A surface water source is to supply a community of 50,000 people at an average rate of 150 liters per capita per day (lpcd). What is the average daily demand in cubic meters per day?
A.3,750 m3/day
B.750 m3/day
C.75,000 m3/day
D.7,500 m3/day
Explanation: Average daily demand equals population multiplied by per-capita demand: 50,000 persons x 150 L/person/day = 7,500,000 L/day. Dividing by 1,000 L/m3 gives 7,500 m3/day. Per-capita demand multiplied by population is the standard basis for sizing water supply works.
3Which Philippine law is the principal statute regulating the practice of sanitary engineering and creating the Board of Sanitary Engineering?
A.Republic Act No. 1364
B.Presidential Decree No. 856
C.Republic Act No. 9275
D.Republic Act No. 9003
Explanation: Republic Act No. 1364 is the Sanitary Engineering Law; it regulates the practice of sanitary engineering in the Philippines and created the Board of Examiners (now the Professional Regulatory Board) for Sanitary Engineering. The licensure examination is administered under this act.
4Free residual chlorine is generally preferred over combined chlorine (chloramines) for primary disinfection of drinking water mainly because free chlorine is:
A.A weaker oxidant requiring longer contact
B.Incapable of inactivating viruses
C.A more powerful and faster-acting disinfectant
D.Only effective above pH 9
Explanation: Free residual chlorine (hypochlorous acid and hypochlorite ion) is a stronger, faster-acting disinfectant than combined chlorine, achieving the required CT (concentration x time) more quickly. Chloramines act more slowly and are typically used to maintain a stable residual in the distribution system rather than for primary kill.
5A rectangular sedimentation basin treats 4,320 m3/day with a surface area of 180 m2. What is the surface overflow rate (surface loading rate)?
A.24 m3/m2/day
B.12 m3/m2/day
C.8 m3/m2/day
D.240 m3/m2/day
Explanation: Surface overflow rate equals flow divided by plan surface area: 4,320 m3/day / 180 m2 = 24 m3/m2/day. This loading rate, equivalent to the settling (critical) velocity, governs which particles are captured; typical design values for plain settling fall well within this range.
6Hardness in water is primarily caused by the presence of dissolved:
A.Calcium and magnesium ions
B.Sodium and potassium ions
C.Chloride and sulfate ions
D.Iron and manganese only
Explanation: Hardness is caused mainly by polyvalent cations, predominantly calcium (Ca2+) and magnesium (Mg2+). It is usually expressed as mg/L of equivalent CaCO3 and causes scaling and excessive soap consumption, which is why softening removes these ions.
7In a rapid sand filter, the process used to remove accumulated solids and restore filter capacity is called:
A.Flocculation
B.Aeration
C.Backwashing
D.Coagulation
Explanation: Backwashing reverses the flow upward through the sand bed at a velocity high enough to fluidize the media, dislodging trapped solids that are carried to waste. Rapid sand filters are backwashed periodically when head loss becomes excessive or effluent quality declines.
8The ratio of the maximum day demand to the average day demand for a municipal water system is commonly assumed to be about:
A.1.5 to 1.8
B.1.0
C.0.5
D.5.0
Explanation: Peaking factors account for demand variation; the maximum-day to average-day ratio is typically taken as roughly 1.5 to 1.8 in design practice. Treatment plants are often sized for maximum-day demand, while distribution mains and pumps consider the higher peak-hour factor.
9Water flows through a 0.30 m diameter pipe at a velocity of 2.0 m/s. What is the volumetric flow rate?
A.0.071 m3/s
B.0.566 m3/s
C.0.018 m3/s
D.0.141 m3/s
Explanation: Flow rate Q equals velocity times cross-sectional area: A = (pi/4)(0.30)^2 = 0.0707 m2, so Q = 2.0 x 0.0707 = 0.141 m3/s. The continuity equation Q = AV is fundamental for sizing pipes and channels in water supply.
10Under Philippine drinking-water standards, the most important microbiological indicator organism whose absence signals the likely absence of fecal contamination is:
A.Total dissolved solids
B.Escherichia coli / thermotolerant coliforms
C.Pseudomonas aeruginosa
D.Algae
Explanation: Thermotolerant (fecal) coliforms, especially Escherichia coli, are the standard indicator organisms for fecal contamination of drinking water. Their absence in a sample strongly suggests the water is free of recent fecal pollution, which is why potable water standards require zero E. coli per 100 mL.
About the Sanitary Engineer Licensure Exam Practice Questions
Verified exam format metadata for PRC Sanitary Engineer Licensure Examination (SELE) is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.