Can I discharge arsenic or uranium (and other radionuclide) wastewater from my drinking water treatment system into a dry well on my property?
All discharges from water treatment systems require a MassDEP approved UIC registration (see discussion for preceding question regarding exemption for certain reverse osmosis (RO) reject water for POU systems). In order to approve a UIC registration application for water treatment system discharges, MassDEP assesses whether the discharge has the potential to result in a violation of the drinking water standard in the receiving groundwater. Due to dilution effects, MassDEP may approve of discharges to a dry well that exceed the public drinking water standards, but there is no set limit and each application is considered on a case-by-case basis. MassDEP can not approve of any discharges of water in which arsenic exceeds the federal hazardous waste threshold (Toxicity Characteristic) of 5 milligrams per liter (mg/L) or 5 parts per million (ppm) or in which uranium exceeds 0.600 mg/L or 600 parts per billion (ppb).
