Despite popular belief, municipal water treatment does not remove all particles from a city’s drinking water. Green Water Technologies explains what treatment does and does not do in the following brief Q&A.
Q: What are coagulation and flocculation?
Green Water Technologies: These are often the first stages of water treatment and involve adding chemicals that provide a positive charge to water and a negative charge to dirt and other undesirable particles. The dirt particles then bind together and form larger groups known as floc.
Q: How is water filtered at a treatment center?
Green Water Technologies: Since floc is heavier than water, it settles at the bottom of a large tank; this is the sedimentation process. This sediment is left in the tank while the lighter, cleaner water is pumped through a series of filters made of charcoal, sand, and gravel to remove other, smaller particles.
Q: Does filtration also disinfect?
Green Water Technologies: While filtering does remove some parasites and bacteria, water is disinfected with chlorine like what is used in bleach. This kills many of the remaining contaminants but only while the water remains in the treatment plant. Once it leaves the facility and enters the city’s distribution channels, it may become affected again. Water is also usually fluoridated before being released to the public.
Q: What are some factors that can affect water at this stage?
Green Water Technologies: Failing infrastructure and outdated piping materials can leech contaminants back into water. For instance, a pipe with a small crack may introduce organic compounds (bacterial, parasites) into water as it flows from the water plant throughout the city. While the chlorine typically continues to eliminate many health concerns, minerals and dirt often remain and are either consumed or filtered out by a home’s private treatment system.