The 4 “P”s are factors that should be considered when selecting water treatment gear. They can be applied in any scenario or application. These factors may overlap, and they may be interpreted differently by different people in different situations. There are often tradeoffs that must be made between the 4 Ps, but they provide a framework for making selections of water treatment equipment.
WATER TREATMENT BASICS
First, let’s take a quick technical dive into water hazards and treatment techniques. The basic categories of hazards include Crunchies, Chemicals, and Critters.
Crunchies are a range of objects from sticks and stones, and sand, sediment, and silt, and micro-plastics that are typically addressed with physical filtration. Filtration is a screen door process that physically blocks particles from remaining in the water.
Chemical hazard is any dissolved or mixed in molecular compound that is not H2O (water). The best way to remove unwanted chemicals is with a process called adsorption, which is most commonly performed by an activated carbon filter medium. Adsorption is the process where unwanted chemicals are attracted to, or bonded to the filter medium and sequestered from the water supply. Typical chemical hazards include pesticides, herbicides, lead, mercury, VOCs, and PFAS. For drinking water, often chlorine and chloramines are unwanted chemical contaminants, but can also be present to control microbiological hazards. Healthy minerals should typically not be labeled as unwanted chemical contaminants, as these are beneficial.
Critters are bacteria, protozoa, and viruses. These are microorganisms that will make you sick if you consume more than your immune system can cope with. When they get inside you, these microbes replicate and damage the cells that make up your body. Bacteria and protozoa are very small, and viruses are extremely small, so filtration methods to remove microbes need to be very fine, in the range of 0.2 microns or smaller. Other ways to remove microbes involve disrupting and inactivating their cell structure or DNA. This can (classically) be done with heat by boiling water, or with chemicals such as chlorine that physically damage the hazardous cells. UV rays will disrupt the DNA of microbes rendering them unable to reproduce. All water that is to be consumed must undergo some treatment to inactivate bacteria, protozoa, and viruses to avoid illness.
Keep in mind that treatment methods can affect each other. For instance, it is critical to have good filtration to remove sediment and organic material when using chlorine or UV treatment. Chlorine will react in unwanted ways with organic material, and excessive sediment will block UV rays from inactivating microorganisms.
So what equipment should someone choose to treat their drinking water? The following considerations may be applied to any situation, and may be evaluated, weighted, or interpreted differently by the individual. Keep in mind that these considerations overlap, and may be contradictory. Taken together, they can help you decide how to support your drinking water needs.
Read more in Part 2, the 4 P's of Selecting Water Treatment Gear