Water Treatment Basics: What You Need to Know
Adsorption
How It Works: Contaminants stick to a material like activated carbon, removing organic chemicals, chlorine, and hydrogen sulfide (which causes a “rotten egg” smell).
Common Uses: Pitcher-style kitchen filters, faucet-mounted filters.
Limitations: Does not remove bacteria, so only use with bacteriologically safe water.
Disinfection
Disinfection eliminates harmful bacteria, viruses, and parasites like E. coli, Cryptosporidium, and Giardia to ensure safe drinking water. Methods include UV light, which kills microbes without using chemicals, chlorination, a highly effective solution that leaves behind chemical by-products, and ozonation and hydrogen peroxide, which provide strong disinfection with minimal residue.
Distillation
Distillation purifies water by heating it to steam, leaving contaminants behind, and then condensing the steam back into liquid form. This method effectively removes most impurities, producing nearly pure water. However, it has drawbacks, including high energy consumption, a slow purification process, and potential concerns about stripping beneficial minerals.
Filtration
Filtration removes particles from water by passing it through porous materials. Its effectiveness depends on pore size, measured in microns (µ), with smaller pores filtering out more contaminants. Filtration is commonly used as the first stage of water treatment and is often combined with other purification methods for optimal results.
Ion Exchange
Ion exchange purifies water by swapping unwanted ions with beneficial ones using a resin bed. A common example is water softeners, which replace hardness minerals like calcium and magnesium with sodium. This process can also help remove low levels of iron, nitrates, and tannins, improving overall water quality.
Oxidation
Purpose: Converts contaminants into removable forms.
Example: Iron oxidation turns dissolved iron into a solid that can be filtered out.
Common Oxidizers: Chlorine, ozone, hydrogen peroxide, oxygen.
Reverse Osmosis (RO)
Reverse osmosis (RO) purifies water by forcing it through a semi-permeable membrane, effectively removing metals like lead and arsenic, nitrates, pesticides, and disinfection by-products (THMs). While highly effective, RO systems require multiple filtration stages, produce wastewater (2-4 gallons per gallon purified), and are more suitable for point-of-use applications rather than whole-home treatment.