Looking for a 15-20 gallon water storage container

[cheeto]

I live in an old house in New Orleans, and it is about 3 feet above the ground on stilts, under the house is exposed to the outside. A couple of days of ago I noticed a plugged hole going through my floor about 1/2" in diameter and pushed the plug out. So now I have a small hole that I could fit a pice of PVC pipe through. Since I am running out of room under my tank and the 5 gallon trash is taking up most of that I was thinking of using my spare mag 7 hooked up to a storage container under the house to pump my top off water into my tank. The container will have to be well sealed to keep outside critters and stuff out of it but also have some type of opening so I can pump water into it when I need to fill it. I also realize that I will have to run some time of air line out of it and into the house to allow air to enter when I am pumping water out of it. Also would a mag 7 do fine under my house ? It would probally be about 2 feet from the side of the house so it would not be directly exposed to any of the elements.

Any suggestions on where I can fine such a container ? Would have to be < 24"H.

[cheeto]

I am currently thinking of using a 30 gallon rubbermaid tub with the lid siliconed on and some bulkheads to get water in and out of it. My only problem would be how to tell when it was getting empty... I guess I could always just kinda shake it and see how light it was.

The actual water storage containers I found on ebay are around 80$ for a 30 gallon plus shipping =( So much more expensive then my current 3$ garbage can.