The demise of the Brita water filter jug was followed by a visit to
Costco, wherein we saw one of those under-sink water purifiers with
a reverse osmosis filter that feeds a small tap in the sink. For
a very reasonable $150 this device features a particulate filter,
two graded active charcoal filters, a storage tank and a "final
filter". Since our sink had a hole for such a tap, plugged these thirty
years, we figured that this was a good investment.
(I got a $129 air compressor complete with tank, valves, hose and car/bicycle adapter, so the going was fair.)
Once done, we sat back and checked for leaks. The gizmo came with a
snazzy tap that clamps over a water pipe and pierces it with a
lance built into the tap, which I did not trust at first. It came with
a similar device to access the drain. It needs this---an outlet for
waste water---as it continuously flushes the
reverse osmosis filter while filtering water.
The thing is evidently not water-economical,
but then it does not consume sodium chloride either---very American
in its thinking.
It has a lot of piping, all quarter-inch plastic, to interconnect
all the parts. These are joined by a variety of plastic and brass
fittings. Quite a rat's nest is the end condition of your cupboard.
Here you see the finished hardware.
The big tank behind the flood light holds the reserve of pure water.
The horizontal cylinder at the back is the silver-based (de-chlorinator?)
for the main water tap.
The small horizontal white cylinder above and behind the U-bend is the
final filter (purpose unclear); the three blue cylinders are the
mechanical and charcoal filters, and the horizontal cylinder above
them is the reverse osmosis membrane's house.
The black clamp on the small vertical length of drain pipe below
the RHS sink drain is the outlet device. The inlet device is invisible
behind that drain pipe, but you can see the green-coded pipe leading to it.