Local Ordinances or Permits

Publicly - Owned Treatment Works (POTWs) as described in the "Down the Drain Disposal" section of this manual have the authority to establish their own discharge limits and often set more stringent limits on your facility than the Federal government through their own ordinance. It is imperative that you review your local POTW ordinance and instruct laboratory workers as to the local discharge requirements.

The National Pretreatment Standards were revised and strengthened on July 24, 1990 (55 FR 30082). Owing to these changes, it is likely that your POTWs ordinance will be revised within the next year.

POTW's often set limits on many pollutants (e.g., metals, pesticides, solvents) in the 5-25 mg/l range. For example, discharging 10 ml of a solvent may require over 1,000-fold dilution to meet the limit. If you discharge regulated substances you should calculate concentrations of pollutants in your discharge using estimates of substances discharged and your facility's water consumption rates. Be conservative!