On 21 Apr 2006 07:34:10 -0700, "z" wrote:

off topic, but i saw an interesting idea yesterday;
put a gate valve in the drain line, then below it run a line through a
valve to the cold water supply; so in case of a clog, shut the gate
valve, open the supply valve, and let the water supply blow the clog
downstream and out. from a 1952 mechanix illustrated mag.


DWV systems are not normally designed or tested to high-pressures.
You could easily pop a joint someplace hidden, trying that trick.

Perhaps more to the point, if you're adding extra bits to the
system to deal with clogs, just sticking an extra cleanout 'Y'
wherever you can't get a snake is cheaper and more reliable.