Smoke testing to identify inflow/infiltration areas of sewer system begins this month

posted on 8/13/2026

A city contractor will conduct smoke testing in sections of the city in effort to identify areas of inflow and infiltration of stormwater into the sanitary sewer system. The work is anticipated to occur the week of August 17, weather permitting.

Properties in the affected areas will receive a door hanger alerting them of the smoke testing with contact information. Testing will occur within 1-4 business days of receiving the notice.

Smoke will not enter homes unless there is defective plumbing or dried up plumbing traps. Those who receive the notice are encouraged to dump a gallon of water in plumbing drains, especially those that don't get used often. Defective plumbing may indicate sewer gasses are also entering the building.

When smoke testing occurs, the contractor, Wright-Pierce, will blow non-toxic smoke through a sewer maintenance hole into the sewer pipes. This smoke is similar to what may be used at concerts and theater performances. The field crew then observes where smoke may exit the system. The exiting smoke may indicate that drain maintenance holes, catch basins, roof gutters and/or foundation drains are connected to the sewer system. smoke testing identifies issues for repair, improving the overall efficiency of the sewer system.

The goal of the work is to reduce rain water from entering the sewer system. The work is necessary both for federal and state compliance, as well as ensuring the health and vitality of natural resources like the Great Bay Estuary.

For those with concerns are encouraged to contact Kristin Sullivan of Wright-Pierce at 603-570-7101 or City Engineer Jillian Semprini at 603-516-6450.