what does hard water form?

what can soft water do easier than hard water?

what can form when hard water is heated?

how is scum formed?

what ions cause hard water?

what is Ca2+ good for in hard water?

what is Mg2+ good for in hard water?

what is temporary hardness caused by?

how can temporary hardness be removed?

what is the equation for temporary hardness?

what is permanent hardness caused by?

how can permanent hardness not be removed?

how can permanent hardness be removed using washing soda?

how does an ion exchange column work?

why is ok for the sodium ions to be in the water?

how can the ion exchange column be reused?

how is water treated to be safe for drinking?

why does the use of chlorine have to be carefully controlled when killing microbes?

why is fluoride compounds added to the water supplies and toothpaste?

what are one of the arguments against adding fluoride to water?

how is pure water made?

why is pure water not made very often?