06 Outback LS tank question

[jparadis23]

I just recently purchased an 06 Outback LS and it’s been awesome. I was just cleaning it tonight and took the engine cover off just to check all the fluids and reattach the blower hose that fell off and noticed a piece of pvc piping with a ball valve that is open going into a fitting under the rear seat. I thought that the gas tank was located there. Any chance anyone would know what this pipe/valve would go too?

[james yarosz]

On my 03 outback ls there is a plastic tank that the rear seat sits on.It is not the gas tank.The gas tank is behind it.The tank under the seat has several fittings on it and could probally be plumbed in to be a ballast tank.I never plumbed mine in since we mostly water ski and dont want ballast.Someone may have piped yours in somehow where they could fill it with water for weight and the ball valve could be a drain which would drain into the bilge and the bilge pump would pump out the water.

[Jimm]

I would think that is plumbing for a ballast bag. My 04 has the bag under the rear seat and it is exactly as you described. Perhaps it was plumbed from the factory but wasn't purchased with the optional bag, or the prior owner took it out for some reason.
That said, should you ever want to add one, all the hard work has been done already.