Help with a leak...

[veritycupcake]

Good morning.
My 1990 1.6tdi Westfalia Atlantic has developed a leak.
The last few days I've been noticing puddles on my drive..I initially thought it was the waste water from the sink or a leak from the water tank but I had a look under the van last night and saw this.
It's on the drivers side (left hand) in the middle, the other side of water tank/gas box.
A constant drip...of diesel or mechanical fluid.
Can someone tell me what it is? Appreciate any help.
Thank you in advance.

[multisi]

Thats the fuel pipe return going into fuel tank, could just need a new rubber pipe onto the tank or the metal pipe end of the tank has rusted.

[veritycupcake]

Thank you Multisi.
Appreciate your help.