Cistern Inlet pipe leak

[Plankton678]

Hello,
I have replaced cistern and have minor leak at inlet pipe. It is at the nut next below the actual cistern nut, .i.e. the next nut after the one on the cistern itself.
I am thinking new washer - does anyone have any thoughts. Particularly any that avoid me disconnecting the cistern again.
Thanks.
Incidentally I am trying to stop Roca cistern link which seems quite common..............

 

[Burnerman]

If the inlet pipe is a typical copper tap connector, there's a fibre washer in there that needs renewing.....if its a flexy pipe, there's washers too - but they are thin flat rubber this time.
If the fill valve is nylon, don't overdo the tightening!
John

 

[Plankton678]

Thanks John,
It is a typical copper tap connector - I will renew washer.
The fill valve is what I am connecting to the inlet pipe I assume - this is nylon.
Will overtightening ruin the thread and hence create a leak? I must admit I am finding it tempting to keep applying the pressure!
I am not a plumber by trade as you can see.......
Paul

 

[Burnerman]

The problem with the plastic stuff is actually cross threading, rather than over tightening....Fluidmaster do a Pro fill valve with a brass thread which is good and prevents such nasties.
You may like to smear some sealant around the new washer, but don't let this be pushed deep into the valve.
John

 

[Plankton678]

Many thanks. I am tempted to get that fill valve - saw it on web. One thing puzzles me is why brass seems to be no more expensive than plastic.
Many thanks for the advice. More impressed by you than I am by Roca!