Newport’s sewer system has a long history. Built starting in the 1870s under Colonel George Waring, the original system was combined — one set of pipes carried both sewage and stormwater to Narragansett Bay without treatment. Beginning in the 1970s, the City implemented a sewer separation program to reduce discharges to the Bay. Most of the system was converted, but some combined portions remain in the southern part of the city.

During dry weather, combined sewers carry only sanitary flow and move it to the plant. During heavy rain, flow can exceed the capacity of the pipes and the treatment plant. To protect the plant and prevent raw sewage from backing up into homes, the system is designed to allow excess flow to discharge through Combined Sewer Overflow (CSO) points.

CSO events occur only during significant wet weather when system capacity is exceeded.

Newport operates two CSO treatment facilities:

• Wellington Avenue CSO Treatment Facility (constructed 1978)
• Washington Street CSO Treatment Facility (constructed 1991)

CSO discharges are directed through treatment facilities that screen, store, and disinfect flow prior to discharge. Since their completion and subsequent upgrades, CSO volume has been reduced by more than 80 percent — an estimated 35 million gallons per year — compared to pre-facility operation. Despite significant reduction, CSOs remain an inherent part of legacy combined systems.

Wastewater treatment at Newport’s plant follows a standard multi-stage sequence:

• Preliminary treatment. Bar screens and grit chambers remove large solids, sand, and grit that would damage downstream equipment.
• Primary treatment. Wastewater sits in primary settling tanks. Heavier solids settle to the bottom as sludge; grease and oils float to the top and are skimmed off.
• Secondary treatment. Secondary treatment removes the majority of organic pollution and suspended solids before disinfection. Microorganisms break down dissolved organic matter in aeration tanks. The water then moves to secondary clarifiers where the biological solids settle out.
• Disinfection. Pathogens are inactivated before the effluent is discharged. The Newport plant uses chemical disinfection.
• Solids handling. The sludge removed at primary and secondary stages is thickened, digested, and dewatered for disposal. Solids management is a major operational component and is increasingly influenced by regulatory requirements related to PFAS and biosolids disposal.
• Monitoring and reporting. Effluent quality is continuously monitored and verified through routine laboratory sampling. Results are reported to RIDEM and EPA under the NPDES permit.

The plant was last modernized in a major capital project completed around 1991, with ongoing improvements since. Primary clarifier rehabilitation is the subject of an active capital bond program.

Newport’s wastewater system operates under several overlapping regulatory frameworks:

• Clean Water Act (federal). Administered by EPA. Sets discharge standards and the NPDES permit framework.
• RIPDES permit. RIDEM administers the RIPDES program as the state implementation of the federal NPDES program. The permit specifies what the plant may discharge, in what quantities, and under what monitoring.
• Rhode Island Department of Environmental Management (RIDEM). Administers the RIPDES program, reviews plant operations, and enforces compliance. Compliance is based on permit defined sampling, reporting, and performance standards.
• EPA/RIDEM Consent Decree. Newport operates under a consent decree that sets requirements for CSO control and wastewater infrastructure investment. Much of the capital program over the past two decades has been structured around consent decree milestones.
• CSO Long-Term Control Plan (LTCP). Approved by RIDEM, the LTCP defines Newport’s long-term strategy for managing combined sewer overflows. The CSO Annual Fixed Fee is the ordinance-restricted funding mechanism for this program.
• Industrial Pretreatment Program. The Department regulates industrial users that discharge into the sewer system to protect the treatment plant from loads it cannot handle.

Only three things should go down the drain or toilet: human waste, toilet paper, and the water used to rinse them. Everything else creates operational problems somewhere in the system.

Never flush:

• Wipes of any kind, including those labeled flushable — they do not break down and cause sewer blockages
• Grease, fats, and cooking oils — they harden in pipes and cause backups
• Paper towels, tissues, hygiene products, diapers
• Medications — they can pass through treatment and reach the Bay
• Chemicals, paints, solvents, motor oil
• Dental floss, hair, or anything stringy

Blockages caused by inappropriate items result in backups into homes, overflows to the environment, and repair costs that are eventually passed to all ratepayers.