Filter media is very critical in ensuring that tap water is safe, clean and useful to households.
In El Paso, its water utilities are designed accordingly to become an advanced purification plant where water is scrubbed through 5 additional steps before it goes into the main water supply. The following steps include:
• Membrane filtration – water is pumped through tubes filled with rolled filter media that has pores measuring one of three-hundredths the width of the human hair. The type of filter media used here can remove solids, bacteria and protozoa including some kinds of viruses.
• Nano-filtration and reverse osmosis – after membrane filtration, water is forced at high pressure into another type of filtration. Both processes can remove materials that are 50,000 times smaller than the smallest bacteria or virus that may be present in water. However, reverse osmosis has its drawbacks. It scrubs water so clean that it requires adding of certain minerals after the process.
• Ultraviolet light – when hydrogen peroxide is added to water, all contaminants that have remained in water will be destroyed once ultraviolet light passes through it.
• Carbon filtration – when water is passed through grains of carbon that have been activated or superheated, the vast number of tiny pores will open up so as to trap remaining particles contained in water. To make the process easier to understand for a typical individual, carbon filtration is like punching millions of additional holes on a block of Swiss cheese. This was how Daniel Olson, project engineer of Arcadis US Inc. explained the process.
• Water storage – water will then be stored so that if there is a glitch in the monitoring system, it will still be detected. Operators will be given enough lead time to stop feed from the advanced purification plant into the water system. Texas Commission on Environmental Quality requires one day lead time for a 10 million gallon tank but according to Gilbert Trejo, chief technical officer of El Paso Water Utilities, the water utility is trying to convince the commission that less time is needed and that a smaller storage tank will do in order to save on costs.