Wiring from Forward Storage on 458

I have a copy of the deck and hull cable routes.

This shows the cables for nav lights, chain counter and windlass running aft at the port hull-deck joint level.  They reach a junction point (DG2) which is in the position of the forward cabin heads compartment forward wall.  I imagine that they continue to run at high level aft to the navigation table area.  Unfortunately this is behind the inner molding.

In my experience the conduits are too full and follow too twisty a path to get much through them.

I have had success getting wiring from the mast back to the void behind the mirrored heads cupboard then down to the bilge and aft to the nav area.

I have just fitted an additional water tank under the floor of my bow locker and have a pump fitted to transfer the contents of this to the main tank.  I have not yet worked out how I will power this, but in the absence of anything else I will piggy-back onto the existing cables for the windlass control.  I have already uncovered these (positive, negative, up and down) to fit a wireless control unit for the windlass.

What do you require power for?

[Edit: Transferred 150l from my bow locker tank to main tank using the wiring from the windlass to power the pump.  5l/m so took about 25 minutes, but it will only be done occasionally to extend time on anchor. Very happy with the low cost (approx €100) solution.]

We are anchoring most nights so decided to try to extend our water storage.  We have a Plastimo 150l flexible tank / bag which I have placed under the grating floor of the bow locker.  I lined the locker with foam mats to minimise chafe and the bag has attachment points at either end.  

I cut the 38mm filling hose to the main tank and inserted a Y valve to allow me to divert the filling to the new tank as required.

This was something of an experiment and I wasn't convinced it would work so I just got a budget pump from China/eBay.  This takes the 12mm outlet from the bag and it just pumps into another hose that I insert into the deck filler when I need to transfer.  It runs at 6l a minute so takes a while.

We have just spent 15 nights anchored, swimming and showering every day so I declare it a success.