27 CFR §22.93

1. (a)Location. All equipment used to recover and restore tax-free alcohol for reuse shall be located on the permit premises.
2. (b)Construction.
   1. (1)Distilling apparatus, pipelines and other equipment used for recovery and restoration of tax-free alcohol shall be constructed and secured in such a manner as to prevent unauthorized access and so arranged as to be readily inspected.
   2. (2)Storage tanks shall be provided for the collection of recovered tax-free alcohol. Each storage tank shall—
      1. (i)Be durably marked as to use and capacity;
      2. (ii)Be equipped with, or for, an accurate means of measuring the spirits; and
      3. (iii)Be equipped for locking to control unauthorized access to the spirits.