sf wrote:
>
> On Thu, 05 Dec 2013 08:44:07 -0500, "Pete C." >
> wrote:
>
> >
> > Ed Pawlowski wrote:
> > >
> > > On 12/3/2013 2:52 PM, Helpful person wrote:
> > >
> > > >
> > > > Unfortunately the water where I live is horrible so I am forced to use bottled,.
> > > >
> > >
> > > Either an RO system or proper filters will pay for itself over bottled.
> > > You do have choices.
> >
> > The $150 or so under counter RO systems work very well and are very easy
> > to install.
>
> What is the "waste ratio" all about and why do the lower cost units
> have a higher one?

The reverse osmosis membrane essentially passes only clean water, which
means that the contaminants stay on the input side of the filter. This
water with concentrated contaminants generally needs to be disposed of
as "reject water" to keep the crud from building up and preventing new
water to be filtered from getting to the RO membrane. Higher end units
have better designs to allow for less reject water and thus less water
consumption.

A key thing to keep in mind is that the under sink RO systems only
produce up to ~10 gal/day of filtered water, and the reject water is
only produced in proportion to the filtered water produced. Thus if the
ratio of reject water to filtered water is 1:3 the unit only "wastes" up
to 3.3 gal/day of water, and if you only use 1 gal of filtered water in
a day it only wastes .3 gal of reject water.

If you are particularly frugal that reject water can be collected for
other uses such as watering non-food plants or flushing toilets or
similar where the increased concentration of contaminants won't be an
issue. This would require some work on your part to do since such
reclamation setups aren't commercially available for a small home unit.