This uses chemicals that bind with other waterborne compounds to form larger particles, which creates a solid mass called floc. As floc is denser than water, it drifts to the bottom of the water treatment tank during a sedimentation process , settling in a removable layer.
Once the suspended floc has been removed, the residual clear water is passed through sand, gravel, or charcoal filters that take out dissolved particles , parasites, bacteria, viruses, and toxic chemicals. The final water treatment stage is disinfection with chlorine. This process not only removes remaining pathogens, but keeps the water supply clean as it passes through the pipeline.
While all municipal water supplies pass through a standard treatment process, your water may undergo different levels of treatment depending on where your water comes from. For example, surface water needs a higher level of coagulation, sedimentation, and filtration than groundwater because water taken from lakes, rivers, and streams is likelier to contain more sediment and higher levels of contaminants than naturally-filtered groundwater.
Every water supply also requires disinfection to guarantee the water becomes and remains safe to use. Typically, disinfection uses chlorination, chloramines, ozone, or ultraviolet light. The risks associated with chlorine have moved utility companies to look at alternative disinfectant options.
Ozonation is often to remove pathogens from the treated water supply. However, chlorine is still required as ozone cannot keep a supply contaminant-free once it has left the treatment plant.
Another disinfection option is ultraviolet light: UV from a lamp destroys viruses and bacteria. In , in Flint, Michigan , the city switched its primary water source to the Flint River. The water treatment services were not adequately set up to treat a highly corrosive water supply that caused health issues throughout the local population. The Flint River water was so corrosive it caused the heavy metal to leach into the supply after the water had passed through the main treatment facilities, highlighting the risks along any water system.
Then the water is treated with chemicals or ultraviolet light to kill harmful bacteria and viruses 4. Following this disinfection step, the water now is ready to flow through pipes to homes throughout a community 5. Different communities may tweak this process in some way. They may add chemicals at different stages to trigger reactions that break down chunky, toxic organic molecules into less harmful bits.
Some may install an ion-exchange system. This can separate contaminants by their electric charge to remove ions. It may also take out heavy metals, such as lead and arsenic, or nitrates from fertilizer runoff. Cities mix and match different processes. They also vary the chemicals used, based on the qualities chemical recipe of the incoming local water. Some water companies are streamlining their treatment process even more by installing technologies such as reverse osmosis Oz-MOH-sis.
This technique removes nearly every contaminant in water by forcing the water molecules through a selectively permeable membrane — one with really tiny holes. Reverse osmosis can replace a number of steps in the water treatment process or reduce the number of chemicals added to water. More than one in every seven U. These are not regulated by a federal law known as the Safe Drinking Water Act. First, it simply costs too much, and second, We start with the water that the municipal water suppliers call their final product!!
If society could take a step back in time and redesign its water supply systems — there would actually be two systems. One system would distribute very high quality water for drinking and cooking and the other system using a completely separate set of pipes would distribute much lower quality water for all of the other tasks.
So, back to the question — is purified water the same as tap water? The answer is most definitely no. I do not know of a single municipal tap water that meets the US Pharmacopeia definition for Purified Water. Our water not only meets the standard, we blow it away. It is very, very pure. Our process begins with municipal tap water in much the same way that paper begins from a tree or a steel beam begins from iron ore or cheese begins from milk or gasoline begins from crude oil.
Paper is not a tree. Steel is not iron ore. Cheese is not milk.
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