Leaking valve under sink

[SRJDIY]

Hi, novice here. Yesterday evening I discovered that a valve underneath my kitchen sink is leaking. To give an idea of the leakage rate, I dried off the valve and the area underneath it last night, and a puddle a couple of inches wide formed over 12 hours or so.

I've attached a couple of pictures of the valve - the drip forms at the bottom of the white-ish plastic ring (where the arrows are). Both the blue hose and the copper pipe it's attached to go out the side of the cabinet, not up to the sink. I'm assuming one is for the washing machine next to the cabinet and one is for the garden tap on the other side of the wall.

Does anyone know what this bit of plumbing is and how best to fix it please? Given I know nothing about plumbing, is it best to attempt a fix myself or play it safe and pay for a plumber?

 

[Fred Blogs]

Those white connectors have a rubber washer inside that gets deformed and or perished over time Assuming it is the white plastic fitting that is leaking buy a couple of suitable washers from B&Q or somewhere like that, these are from Screwfix https://www.screwfix.com/p/flomasta-washing-machine-hose-washers-3-4-10-pack/53909 don't forget to turn the blue tap off before you undo the white plastic fitting. If it's the brass fittings that are leaking and you are not competant with plumbing then I would suggest you call a plumber in.

 

[SRJDIY]

Those white connectors have a rubber washer inside that gets deformed and or perished over time Assuming it is the white plastic fitting that is leaking buy a couple of suitable washers from B&Q or somewhere like that, these are from Screwfix https://www.screwfix.com/p/flomasta-washing-machine-hose-washers-3-4-10-pack/53909 don't forget to turn the blue tap off before you undo the white plastic fitting. If it's the brass fittings that are leaking and you are not competant with plumbing then I would suggest you call a plumber in.

Thanks for the advice! Just a few questions please:

1.) If the white plastic connector is stiff, is it ok to use a monkey wrench to loosen it, or will this just crack the connector and necessitate a new hose?
2.) When I'm screwing the connector back on, how tight should it be tightened? I've heard that over-tightening can damage the connector.
3.) Do I need to use plumbers tape when screwing the connector back on?
4.) Is it safe to run the washing machine before this is fixed? I don't want to flood my kitchen by accident!

 

[terryplumb]

The hose connector would usually only need to be hand tight ,but a pair of grips can be used to nip it up a tad tighter if need be ( or to loosen it).
No PTFE tape required ,only a new 3/4 hose washer.
Appliance can be used ,the dripping connection will still drip !

 

[JohnD]

It depends how strong your hands are, but often a pair of rubber household gloves will give enough grip on the plastic nut. Hold the hose so the fitting is perfectly straight before you screw it on.