I doubt that it would be build-able in a form that doesn’t leak. Six feet tall would mean about 3 psi at the bottom. 432 pounds per sf. An eight foot span would have tens of thousands of pounds of force between the two sides pushing them apart.
Why not just have a cistern? Much cheaper and reliable.
13,000 gallons of water would be quite a flood if something were to breach such a water fence. Perhaps a falling fir tree or an earthquake would do it. Even a small leak would be a disaster because how do you plug such a leak?