How Do We Treat the Water So That You May Drink It?

Like the majority of water utilities in the U.S., we use a multi-step treatment process at all three of our drinking water treatment plants.  This Water Treatment Process diagram provides a brief description of drinking water treatment in Philadelphia.

The River The source water comes from either the Delaware or Schuylkill River.

Natural Settling Water is stored in reservoirs or basins after it has been pumped from the river to allow sediments to settle.

Disinfection Chlorine is added to kill disease-causing organisms.

Coagulation The river water is "coagulated."Chemicals are added to the water to cause smaller particles in water to join together . This makes them heavier so that they will settle to the bottom of the basin.

Flocculation The water mixed to make sure the added chemicals are well blended and react with all of the smaller particles. The particles combine to form "floc" which settle to the bottom of the basin.

Sedimentation The newly joined particles or "floc" settle by gravity and are removed from the bottom of the mixing tanks.

 

Filtration The water is drawn through filters, which remove finer particles still in the water for additional purification.

Final Treatment Fluoride is added to help prevent tooth decay, while zinc orthophosphate is added to minimize corrosion activity between water and piping materials. Ammonia is added to reduce chlorine-like tastes and to maintain the chlorine in the water.

Distribution