Properties of Water & Water Treatment

Vocabulary flashcards covering key terms and processes related to water properties, quality issues, purification methods, and the Metropolitan Cebu Water District’s treatment systems.

Water Cycle

The continuous process in which water evaporates, condenses, and precipitates, naturally purifying itself through evaporation and condensation.

Evaporation

Phase change of liquid water to vapor, leaving salts and solids behind and helping purify water.

Condensation

Conversion of water vapor to liquid droplets, producing fresh water unless airborne pollutants are absorbed.

Relative Humidity (RH)

The ratio of actual water vapor in air to the maximum it can hold at that temperature, expressed as a percentage.

Impervious Layer

A soil or rock layer that does not allow water (H₂O) to pass through.

Purified Water

Water that has undergone a process in which pollutants are removed or rendered harmless.

Polluted Water

Water containing impurities that make it unsuitable for a desired use.

Gray Water

Wastewater drained from lavatories, sinks, laundry trays, and showers that contains minor pollutants.

Black Water

Wastewater from water closets and urinals carrying body wastes and major pollutants.

Storm Water

Rainwater collected from roof gutters and downspouts.

Acidity (in water)

Water containing dissolved carbon dioxide that corrodes non-ferrous pipes and rusts steel piping.

Hardness

Water characteristic caused by calcium and magnesium ions, leading to pipe clogging and hindered laundering.

Turbidity

Cloudiness caused by suspended silt or matter picked up in surface flow, resulting in discoloration and bad taste.

Water Color Problem

Discoloration due to dissolved iron and manganese, staining fixtures and laundry.

Water Pollution (quality problem)

Contamination by organic matter or sewage that can transmit disease.

Zeolite

A greenish granular water-softening material used to remove hardness-causing ions.

Water Softener

A device or substance (often zeolite-based) that replaces calcium and magnesium ions with sodium to reduce hardness.

Water Purification

Any method that removes materials making water unsuitable for a given use.

Settling (Sedimentation)

Allowing suspended solids to sink by gravity to clarify water.

Filtration

Passing water through a porous medium to remove remaining suspended matter, microbes, and colloids.

Adsorption / Coagulation-Flocculation

Chemical-physical process where small particles destabilize (coagulation) and agglomerate (flocculation) into larger settleable flocs.

Aeration (treatment)

Spraying or mixing water with air to release gases and add oxygen, improving taste and aiding iron removal.

Distillation

Purification method where water is evaporated and condensed, leaving impurities behind.

Disinfection / Chlorination

Addition of controlled chlorine to kill pathogenic organisms and ensure sanitary water quality.

Coagulation

Chemical step using a coagulant (e.g., alum) to neutralize particle charges, enabling floc formation.

Flocculation

Gentle mixing stage that encourages destabilized particles to collide and stick, forming larger flocs.

Sedimentation (plant stage)

Holding coagulated water in basins so flocs settle before filtration, reducing filter load.

Metropolitan Cebu Water District (MCWD)

Sole commercial water provider for Metro Cebu, tasked with supplying adequate, safe, and affordable water.

Groundwater (MCWD)

Water naturally filtered through deep sands and rocks; MCWD treats it only by chlorination before distribution.

Surface Water (MCWD)

Runoff stored in a dam and subjected to aeration, coagulation-flocculation, sedimentation, filtration, and chlorination.

Buhisan Dam

Cebu’s first and only dam supplying MCWD’s Tisa filter plant with up to 600 m³/hour of surface water.

Alum / Tawas (Aluminum Sulfate)

Coagulant added to surface water to aid coagulation of organic particles.

Soft Water

Water low in calcium and magnesium, preferable for boilers, laundering, and preventing pipe scaling.

Hard Water Correction

Use of ion-exchange water softeners containing zeolite to replace hardness ions with sodium.

Acidic Water Correction

Passing water through crushed marble/limestone or adding sodium silicate to achieve alkalinity.

Chlorine Gas

Disinfectant MCWD injects into water to eliminate coliforms and other bacteria before storage and distribution.