Is Our Water Safe to Drink?

The quality of our drinking water is one of the most important subjects and is usually on the mind of everyone, including federal and local government agencies. There are drinking water standards that must be met by water treatment facilities or their plants could be shut down until the standards are met. In addition to bacterial or viral contamination, there are also parasites like giardia or cryptosporidium that need to be removed. As if these aren't problem enough, much of the natural water supply is also laced with a variety of heavy metals like lead or copper. While small amounts of these metals or bacterial might be acceptable to the human body, larger amounts definitely are not. Some elements that are removed from the water are to enhance taste or smell, and are not necessarily for health reasons. However, a set of maximum allowances are set to protect the consumer against the contaminants that are harmful.

There are several effective methods of removing contaminants from the water supply depending on the origin of the water. Public supplied water comes from underground aquifers or from surface water, and while some cities are employing the use of reuse or recycled water, it is generally only used for landscaping. A lot of groundwater is relatively pure, but it can sometimes be contaminated with bacteria or metals that have leached down from the surface. Obviously, the purer the water, the less expensive and easier it is to treat. Almost all surface water requires significant treatment to get it to drinking water standards. There are many pollutants and contaminants that can affect surface water due to the fact that it is exposed, unlike groundwater. The problem with using groundwater is that the aquifers are generally limited in the amount of water they contain and rely on recharge to refill the aquifer. Recharging a deep aquifer could take thousands of years, so depleting it isn't wise. Even spring water, which is groundwater that naturally surfaces from a spring, still must be tested for purity.

Once water is transported to a treatment facility, it goes through an initial screening and filtering which removes large things like trash, animals or insects. Groundwater generally wouldn't need to be screened or filtered since it was not exposed to the outside. There is usually a sedimentary tank so that particles can settle out onto the floor of the tank, and then it passes into large tanks were a flocculation process takes place. A type of material like aluminum sulfate, known as alum is added to the water and causes fine materials to join together, collecting into clumps known as floc, that are then easily scraped from the surface. The next step of the process is the disinfection stage. This can be done with chlorine or even ultra violet light. Either way is effective in killing bacteria and some viruses. The water is always randomly sampled before it is discharged into the public water supply. Depending on how contaminated the water supply is, it may need a secondary treatment or even a tertiary treatment until it reaches the health standards.