| Hi,
I am not a plumber, just a sometimes do it yourselfer around our home.
I would replace the valve that's leaking. The seals inside might be worn out, and no amount of tightening will stop it normally.
If the knob and it's assembly "screws into" the part attached to the pipes, it might be possible to unscrew it, (after turning off the water, of course!), and buy just that part. I did that with a "metal" valve feeding water to one of our toilets.
But, if the whole valve assembly is plastic, it would be easier to replace it all. |