Water Treatment Glossary


Compensated Hardness
A measure of water condition used for determining water softener capacity. It takes into account the amount of iron present in water as well as hardness. To determine compensated hardness, add twice the iron content to the actual hardness.

Example: Actual hardness = 20 gpg Twice the iron content (2x3) 6
  Iron Content = 3 ppm Plus the actual hardness   + 20
  Equals the compensated hardness   26

Grains per Gallon. A measurement of the amount of dissolved material in water. One grain per gallon (gpg) equals 17.1 parts per million (ppm).

Greywater, simply put, is washwater. Greywater is all wastewater, with the exception of toilet waste and food waste from garbage disposals, which is considered blackwater. Greywater treatment and greywater recycling are growing in popularity and use as a way to recycle and conserve water. These methods are very environmentally friendly. These methods, which can be used in both residential and industrial or commercial environments, create an opportunity to not only conserve water, but also conserve costs. In a typical setup, all water from sinks, showers, washing machine, etc. is sent to the greywater treatment system, where it is cleaned and then this water is held in a holding tank until it is needed. Typically, treated greywater is used to flush toilets and also for outside water needs, such as watering the lawn or flower beds. Greywater can be treated so that it is safe for human consumption with the correct treatment system.

Electrically charged particles that form when any mineral is dissolved in water. For example, when common table salt (NaCl) is dissolved in water, it forms positively charged ions (Na+) and negatively charged ions (Cl-). The positively charged ions are called cations and the negatively charged ions are anions.

Term used to express the acidic or basic strength of water. The pH scale ranges from 0 to 14. A pH of 7 is neutral, indicating a balance between acidic and basic elements. Values below 7 indicate increasing acid strength as the pH approaches 0. Values above 7 indicate increasing basic strength as the pH approaches 14. Note: Waters with a pH below 5.5 require special attention. Send a water sample to our laboratory for analysis and recommendations for treatment.

Parts per Million. A common term used in water analysis. One part per million (ppm) equals one pound per million pounds of water. Parts per million may be converted to grains per gallon by dividing by 17.1. One part per million is equal to one milligram per liter.


Rainwater Harvesting
Rainwater Harvesting is the process of gathering rainwater, typically runoff from the roof of a building. After it is gathered it is stored in a large container, either on top of the ground, or buried underground. Rainwater can be saved and used to water plants and gardens, or it can be treated and used inside the house. Typically, rainwater is not used for human consumption, although it can be with the proper water filtration and processing system. Stored rainwater is usually used for flushing toilets, washing clothes, etc., as well as its' use outside (watering grass and flower gardens, washing cars, filling swimming pools). Only 1% of the water than an average person uses in a day is used for human consumption. This means that harvested rainwater could potentially make up 99% of the water that is used in your household or business. And with the proper filtraiton, 100% of the water that is used could be from harvested rainwater.


"Ultraviolet" is a form of light that can be harnessed and used for water disinfection, killing even the most dangerous bacteria and viruses commonly found in drinking water. The ultraviolet range is ideal for killing micro-organisms such as e-coli, coliform, cholera, legionaires disease, hepatitis, etc. And PURA's 5.0 micron EPCB (Extended Pass Carbon Block) filter also removes crytosporidium and giardia cysts, and cleans the water by eliminating sediments, chlorine and chlorine byproducts. We recommend PURA's patented water treatment systems which provide water disinfection, through the combination of ultraviolet technology and carbon filtration.