Water tank exit hose for 1998 Symphony

Hi
I am new to this so any advice greatly appreciated.
Just bought a 1998 Symphony and the previous owner said 'water tank needs new exit hose. a very good dealer said its about £40'. 
Can i find one anywhere? No!
Took it to the garage and they cant find one that works either.
Any ideas what exactly I'm looking for?
Surely it cant be that hard, I'm sure you need to replace these things over time.

Looking for help, advice and ideas and maybe somewhere that sells used parts or something? 

Update: it's for the white water into blue tank
Thanks :)

I had a 97 Symphony  but can't remember  the pipe. I know its clips under the sill. Have you got the old pipe? If it's like newer models its simply 1" (25mm) diameter convoluted pipe with a barrel tap on end. As long as you have the spigot on the tank to attach it to , its simple to replace. Pipe is available  from CakTanks or AS spares, grey colour but you can get black from garden centres who stock garden pond supplies. Sold by the metre. Hopefully  a current Symphony owner can confirm.

Micky

Someone will answer later.