Plumbing Nightmare

[sphelps]

I would just preform a small test.

Glue an extra fitting to some extra pipe using the same ABS glue you used on the tank. Let it sit overnight and see if you can pull it apart.

If you can't pull it apart or it takes a lot of force to do so you'll be fine. Typical PVC pipe applications usually see pressure in the range of 40 to 60 psi. Your tank shouldn't expose it to more than 3 psi so it's a very low pressure application. Also if a leak does start it'll start as a slow drip, the fittings aren't going to just explode open.