Eventually all taps drip. It's fate, like toast falling
butter side down. The traditional style of tap forms a
seal using a ring of rubber screwed down onto the end of
the metal feed pipe. In time the rubber, either becomes
brittle and splits, or just wears through and it will then
no longer properly seal. If the washer is not replaced
immediately, water seeping through the gap will erode the
valve seat. The choice then is to either, replace the tap,
or re-grind the valve seat, assuming of course, that you
have a valve seat re-grinder handy. Not good either way.
But, these days there is now an alternative. Ceramic disc
taps.


How They Work

Instead of blocking the pipe by squeezing a piece of
rubber onto the end of it, there are two slotted ceramic
discs held down over the water supply pipe. The bottom disc
doesn't move, while the upper disc is rotated over it by the
tap mechanism. When the slots align the the tap is on, and
when the slots don't align, the tap is off.


Advantages

This arrangement has numerous benefits. The main one is
due to the ceramic discs being very hard and thus highly
resistant to the erosion caused by the seepage of water pass
the discs. This results in the discs having a greatly
extended life before replacement is required. Also, because
the flow of water is between the discs, erosion occurs in
the discs not in the metal valve seat. Additionally,
because of method of operation, the taps are turned on fully
by just a one quarter turn and only light pressure is
required. This has the benefit of the taps being simple to
turn on with the back of the hand if they are dirty and for
those people who have restricted hand or finger movement.


Disadvantages

There are a number of disadvantages to this type of tap.
They are more expensive and the discs do eventually wear
out. However, manufacturers seem to all use standard sizes,
so it is usually easy to get replacements. Because basin
taps are sometimes handed and sometimes not, it can be
annoying to have to find out which way to turn the tap to
get the water flowing. They are also not suitable for very
low water pressure. The last disadvantage is that if you
are used to traditional style taps, which use a number of
turns to go fully on, you may accidentally turn on the tap
far more than you intended. This can lead to an unexpected
full-flow jet of water, going everywhere. Not Good!


Where they are Used

The ease of operation and the long life mean that most good
quality sink mixer taps have been made using ceramic discs
for a while, but basin taps with ceramic discs are
surprisingly less common. The more use a tap gets, the more
attractive the use of ceramic disc technology becomes. This
is doubly true in hard water areas, which can be murder on
traditional taps.