Hi there, it's Lio.

I followed the link you sent me and I'm now logged in under your ID!?

Anyway, here's my 0.2Euro opinion on the water storage subject:

When travelling with kids in a 4x4, the trunck tends to fill really fast (as you know ;o) but it's a strategic place for everyday life on the piste so should be loaded adequately.
In priority, I would use the trunck for things I cannot fit anywhere else on the vehicle and should be easily and quickly accessible (clothing, cookware, food, wine, kid toys, ...). In my case, all the roof is taken by the family rooftent so tools, recovery gear and the like need to find a place in the vehicle - and not under the car as they need to be accessible even if the vehicle is stuck - so they'll end up in the trunck.
This leaves very little palce in the trunck (unless comfort is compromised) an quiet some space under the vehicle. Space to be used in priority for things that are easy to "put" in and out (liquids? ;o) and are heavy (liquids? ;o).
=> For that matter, I'll statch all the liquids I can (water, fuel, oils, more wine ;o) under the vehicle.
It's easy to take it out with a submerged pump or inline pump that will not have to be installed/removed everytime water is needed.
It's a little more difficult to get it in but it's only water so you can poor it as slow as you want (unlike fuel) and can bear spilling a bit. My friend Franck who made his own under-body tank on the opposite side of the front muffler (LandCruiser HDJ80) fills it in thanks to a filer pipe that comes up under the bonnet, by the brake booster. The filler being so high, you could make several small tanks and fill them all up from the same filler. I know some people also use the space available when you remove the main muffler (HDJ80).
If this solution is the best to my eyes, I agree it's not ideal (but is there one ideal solution?) as the tanks are not transportable and not easily washable. That's why I'd still carry with me a empty 10L jerrycan (or the swiss army bags?) to carry the water from the source to the truck if needed.

Hope this help.

Lio
HDJ80 - France

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Cheers,

Julian Voelcker
Overland Cruisers - Specialising in Land Cruiser preparation and servicing.