Fuel tank sump drain?

[alaskaflyfish]

After reviewing fuel related posts from times past I decided to remove my 13 gallon diesel fuel tank and do some preventative maintenance. Due diligence was the order for the day and what I found was shocking. First, the amount of corrosion on the outside of the aluminum tank bottom where it sat on an elevated shelf, as well as the corrosion under the hold down straps. Sorry no pictures but imagine heavy pitting on .090 skin thickness. The inside bottom corrosion pitting was just as bad due to water contamination. The real shocker in all this was the amount of water I drained out. I estimate about 2 quarts of the ugliest bio-growth I have ever seen. I have been around jet fuel for a long time so I am worthy of my opinion on Bio-growth! So off the the weld shop for a new bottom and a slathering of Pro Seal fuel sealant on the top. So here I sit wondering why in the world does this tank not have a sump drain attached? This may not solve all my fuel tank problems but it could certainly solve one big problem which is water contamination. How else do you get water out? Aircraft have sump drains that seem to work very well, why shouldn't sailboats? What am I missing here? Any thoughts and musings on this subject by like minded sailors would be helpful. The tank is still out and can be taken back to the weld shop for a sump valve installation. Thanks ....Tim M