Basics of Plumbing, Water Supply, Drainage & Ventilation – AQE Reviewer

A comprehensive set of Q&A flashcards covering fundamental terms, systems, materials, and principles in water supply, plumbing fixtures, drainage, venting, storm water management, sewage treatment, and Philippine plumbing regulations.

What is the primary purpose of a Domestic Water System inside a building?

To deliver pressurized potable water for drinking, cooking, bathing, and other uses.

From where does a Domestic Water System typically receive its supply?

Either a city water main or a well system.

Into what two subsystems does potable water divide once inside a structure?

Cold-water subsystem and hot-water subsystem.

How is water converted from the cold-water subsystem to the hot-water subsystem?

Cold water is routed through a water heater before being distributed as hot water.

What does DWV stand for in plumbing?

Drainage, Waste and Vent.

Which plumbing system relies on gravity and is not constantly full of water?

The sanitary waste (DWV) system.

In DWV terminology, what type of water does the letter “D” represent?

Draining grey water from tubs, sinks, and washers.

In DWV terminology, what does the letter “W” denote?

Waste from water closets (black water).

What is the function of the “V” in DWV?

Venting—admitting air into and out of the system.

What is the typical diameter of a main soil stack?

3–4 inches (75–100 mm).

What is the usual diameter range for a secondary (vent or waste) stack?

2–3 inches (50–75 mm).

What material followed cast iron as the next common choice for drain stacks?

Galvanized steel.

What problem can porous main drain lines experience outdoors?

Blockage by tree roots.

Define Positive Air Pressure in plumbing drainage.

Air pushed ahead of falling waste in a pipe, helping move waste along the line.

List three typical contributors to plumbing wastewater.

Toilets, sinks, and washing machines (also tubs, showers, dishwashers).

What is ‘surface water’ in the context of plumbing?

Water collected on the earth’s surface such as rain runoff, rivers, lakes, or roof water.

What device marks the official start of a building’s water service?

The water meter.

Give the general definition of plumbing.

The system of pipes, valves, fixtures, and other apparatus for water supply or sewage.

What is an aquifer?

A geological formation that contains or conducts usable quantities of groundwater.

What Philippine law is known as the Plumbing Law of the Philippines?

Republic Act 1378.

What percentage of a building’s construction cost typically goes to plumbing and sanitary work?

8–10 %.

What is potable water?

Water fit for human consumption.

What is a water main?

A main conduit through which a public water system conveys water to service connections.

What is the purpose of a curb cock (curb stop)?

To shut off the water supply to a building in an emergency from outside.

Name two common materials used for potable water tanks.

Fiberglass and stainless steel (others: polyethylene, corrugated steel, etc.).

State one key difference between hard and soft water.

Hard water contains high calcium/magnesium salts and does not lather easily; soft water has little dissolved solids and lathers readily.

Why is an indirect water-supply system common in many Asian countries?

Municipal water pressure is low, so underground and overhead storage tanks plus pumps are used.

What distribution method uses a pressurized air tank to push water upward?

Pneumatic (up-feed) water supply system.

Describe a gravity (down-feed) water system.

Water is pumped to a rooftop tank and then flows by gravity to fixtures below.

What is the primary purpose of vent pipes in a DWV system?

To allow air circulation, eliminate gurgling, and protect trap seals from siphonage and back-pressure.

Define a stack in plumbing.

A vertical waste or vent pipe serving two or more floors.

What is a cleanout?

A fitting with a removable plug giving access to a soil or waste pipe for cleaning.

What does ‘fall’ mean in drainage design?

The downward slope of a pipe, expressed in inches per foot or as a percentage.

What is a wet vent?

An oversized pipe that functions as both a drain (soil/waste) and a vent.

Differentiate between a building drain and a building sewer.

Building drain is inside the building conveying waste to the point 900 mm outside; building sewer connects that point to the public sewer or septic system.

What is a trap seal?

The vertical depth of water retained in a trap preventing sewer gases from entering a building.

What is storm drainage responsible for?

Collecting and discharging stormwater (roof and surface runoff) to an approved disposal point.

Describe a detention pond.

A dry basin that temporarily holds stormwater and then releases it slowly.

What preliminary device in a wastewater treatment plant removes large debris?

Bar screen.

What is the purpose of an aeration basin in sewage treatment?

To biologically degrade organic matter using aerobic digestion.

Name two common disinfection methods after secondary clarification.

Chlorination and ultraviolet (UV) disinfection (also ozone).

Define a septic tank.

A watertight tank that separates and digests solids with anaerobic bacteria and allows clarified effluent to discharge for further disposal.

What is the minimum manhole access opening for a septic tank as per notes?

508 mm.

What is sludge in a septic tank?

Semi-solid sediment that settles at the bottom during treatment.

What is a transfer pump used for?

Moving water from an underground tank to an overhead tank.

When is a hydro booster pump typically installed?

To maintain pressure for upper floors of high-rise buildings.

What does a check valve do?

Allows flow in only one direction and prevents backflow.

Which valve type is primarily used to open or close a pipeline without throttling?

Gate valve.

Which valve is best for regulating flow and is common in faucets?

Globe valve.

What material is CPVC mainly chosen for?

Hot-water applications up to about 200 °F (93 °C).

Give one advantage of HDPE pipe in water systems.

Flexibility and suitability for mains, gas, sewer, or irrigation lines due to high durability.

What plumbing fixture unit (FU) value is assigned to a water closet?

6 fixture units.

How many fixture units are assigned to a lavatory?

1 fixture unit.

State typical normal water pressure for residential use.

About 80 psi or less (notes list 80 psi normal; 160 psi high).

What diameter trap is required for a kitchen sink (residential)?

1 ½ inch diameter.

What is a pipe hanger used for?

To support and suspend pipes, transferring their load to building structures.

What is gray water, according to the notes?

Wastewater from lavatories, sinks, showers, and laundry (no toilet waste).

Define black water.

Waste containing human excrement, typically from water closets and urinals.

What type of public sewer carries only rainwater?

Storm sewer.

Name the main pipeline that conveys water to Metro Manila consumers.

Aqueducts from Angat–Ipo system (Umiray River to La Mesa/Balara plants).

Which two concessionaires distribute Metro Manila’s water?

Maynilad (West zone) and Manila Water (East zone).

What Philippine agency oversees metropolitan waterworks and sewerage?

MWSS (Metropolitan Waterworks and Sewerage System).

What is a mixing valve used for?

Controlling and blending hot and cold water to a desired temperature.

Explain water hammer and one way to mitigate it.

A pressure surge when flow stops suddenly; install air chambers or hammer arrestors.

What is an air gap in a water-supply connection?

The unobstructed vertical distance between a faucet outlet and the flood-level rim of the receptacle.

Define back-siphonage.

Reverse flow of used or contaminated water into the potable supply due to negative pressure.

What is meant by ‘branch interval’ in a stack?

Vertical length (≥8 ft/2.4 m) between connections of horizontal branches on successive floors.

What is the minimum slope recommended for horizontal drainage pipes?

2 % (or 1 cm per meter).

Which vent type loops back to a stack vent instead of a vent stack?

Loop vent.

What is a sump pump used for?

Removing accumulated liquid from a sump or low pit.

How many gallons per minute does one fixture unit represent?

7.5 gallons or 1 cubic foot per minute.

What does ‘PPR’ stand for in piping?

Polypropylene Random Copolymer pipe.

Name three common sanitary fixtures made of vitreous china.

Water closet, lavatory, and urinal (also bidet, sink).

What plumbing drawing set must be signed by a licensed Sanitary Engineer or Master Plumber?

Plumbing (and sanitary) drawings for the project.

What is the principal advantage of UPVC pipe?

Corrosion resistance for supplying potable water.

Describe a wet vent’s dual function.

Acts simultaneously as a drain for one fixture and a vent for another.

What fitting is a Y-shaped connector joining a branch to a main at 45°?

Wye fitting.

What is a sanitary tee designed to do?

Guide flow from a branch into the main line smoothly with a slight curve.

Explain the term ‘dead end’ in plumbing.

A closed pipe extension permitting stagnation; prohibited in drains.

What is a backflow preventer on a sewer line called?

Back-flow valve or check valve for sewage.

Why are vent stacks sometimes provided with yoke vents every few floors?

To equalize pressure and relieve stress on long vertical stacks.

What causes trap seal loss by direct siphonage?

Rapid discharge from the same fixture without adequate venting pulling water out of its own trap.

Which trap type is built directly into a fixture such as a toilet?

Integral trap.

What minimum vertical rise must a plumbing vent extend above the roof?

At least 300 mm (approximately 12 inches).

Which valve type combines hot and cold water supplies to achieve a set temperature?

Mixing valve.

Give one defining feature of a globe valve’s body shape.

It has a globular body with an internal partition and disk seat.

Where is a foot valve installed and why?

At the bottom of a suction pipe to maintain pump priming by preventing reverse flow.

What is the chief reason to use a pressure-reducing valve?

To keep excessive municipal pressure (e.g., >50 psi) from damaging fixtures and pipes.

State one key requirement for locating public wells per notes.

No outdoor privy, cesspool, or septic tank within 45 m of the well.

What is the required minimum distance between a public well and residential areas?

100 meters.

Why should abandoned wells be sealed?

To prevent contamination of new wells.

What treatment step immediately follows coagulation and flocculation?

Sedimentation.

What is the main function of a grit chamber in a treatment plant?

Allow sand and fine particles to settle out before biological treatment.

What does ‘drawdown’ refer to in groundwater extraction?

The lowering of water table level due to pumping.

Name one water distribution layout method classified as ‘direct pressure’.

Direct pressure distribution—water is pumped directly from source to consumers without storage.

How does an overhead feed hot-water system distribute water?

Heated water rises to the highest point and flows by gravity down to fixtures.

What is the typical working pressure limit for a standard storage boiler per notes?

Not to exceed 85 psi unless designed for extra-heavy duty.

What is a siamese connection in fire lines?

A Y-connection allowing two hose lines to connect to a hydrant/nozzle.

Define ‘pressure drop’.

Loss of head or pressure between two points in a piping system due to friction.

What Philippine organization first promulgated the National Plumbing Code?

NAMPAP (National Master Plumbers Association of the Philippines).