Venturi

A tube with a tapered throat which causes an increase in velocity thus a decrease in pressure of the fluid passing through it. It is the common item used to educt or suck a regenerant into a water conditioning system.

Virus

The smallest form of life known to be capable of producing disease or infection, usually considered to be of large molecular size. They multiply by assembly of component fragments in living cells, rather than be cell division, as do most bacteria. Being parasitic infectious microbes, they are much smaller than bacteria.

Volatile Organic Compounds (VOC's)

Synthetic organic chemicals that vaporize at relatively low temperatures.

Void area

The space between the resin beads in an ion exchange bed or the space between the particles of filter media bed. Also can be defined as the space between the chunks of salt in a brine tank.