Dropping Topaz fresh water tank

I need to change the drain tap on the fresh water tank on my Topaz. I guess I need to drop the tank.
 
Can I do this on a ramps?
 
What tap do I need?  I'd like to buy one before I start.
 
Any other advice?
 

Many thanks!

I'd find out firstly, how the tap is fitted.
It would be a shame to drop the tank, only to find that the nut behind, inside the tank was fixed/welded to the tank wall, and the new tap could have just been screwed in from the outside.    

logburner wrote:It would be a shame to drop the tank, only to find that the nut behind, inside the tank was fixed/welded to the tank wall, and the new tap could have just been screwed in from the outside.    

Heh, no, the nut inside isn't fixed - it spins with the tap.

Oopps !!             

I'm finding this a bit difficult to reconcile with my 2005 Topaz. The tap is on the outer end of a length of flexible pipe and not attached directly to the tank. There is also an access port in the bottom of the tank with a large diameter (approx. 4") screw cap.
CAK Tanks have an extensive stock which is well illustrated in a downloadable catalogue in PDF form. You should be able to recognise your fitting or tap from these illustrations.
Keith

I had this on my 2002 Topaz, I dropped the tank had trolley jack underneath to support tank, took out the tap, it is screwed inside, small hand needed to undo it, then I thoroughly cleaned the tank fitted new tap from screw fix, also renewed the tank hangers, didn`t want them failing  going down the road with a full tank of water.
Hope this is of some help.

It may sound daft, but worth a try, cut off the tap close to the tank without unscrewing it, this might create a space to insert a wire with two hooks to hold the nut within the tank, remove the tap leaving the nut held on wire so it does not drop into tank spread some sealant on the inside of tank with finger, gentle pull nut onto the tank and sealant, when dry, remove the wire and hopefully gentle screw the tap on to the captive nut.

It will be quite tricky doing that unless you have very small hands, when I changed my tap ,hubby couldn`t get his hand in to the tank hole far too small, that is why I did it, I take a size 6 glove, good luck with that anyway.