How H₂S Corrodes Concrete Sewer Infrastructure
Hydrogen sulfide in the headspace of a wet well is oxidized by Thiobacillus bacteria into sulfuric acid, which then attacks the concrete crown. Untreated wet wells lose ¼ inch of wall per year.
How to know if you have it
Look for white crystalline efflorescence at the waterline and a chalky, soft surface above it. Cores tested by a structural engineer confirm depth of attack.
Coating versus treatment
Calcium aluminate coatings buy time but the acid will eventually find a defect. Continuous H₂S treatment at the source prevents formation.
Why it matters
Concrete deterioration can weaken the support around access frames, pipe penetrations, and equipment anchors. Loose material can fall into the wet well and interfere with pumping equipment. A quieter odor complaint log does not establish that corrosion has stopped: gas conditions change with wastewater loading, temperature, and ventilation. Keep condition records separate from odor reports so maintenance decisions reflect the structure, not just what occupants notice.
Practical steps
Review inspection photographs alongside pump alarms, cleaning records, and dosing interruptions. From a safe location outside the opening, document cracks, exposed reinforcement, damaged joints, and deterioration around penetrations. Use consistent photo locations so changes are easier to compare. Check accessible dosing equipment for an empty reservoir, leaking tubing, blocked injection fittings, or loss of power. Record pump operation and unusual wastewater conditions for the service contractor. Do not lean into the opening or enter the wet well to investigate.
When to call a professional
Call a structural engineer if concrete is falling away, reinforcement is exposed, anchors are loosening, or cracking appears around load-bearing areas. Have a qualified wastewater contractor assess pumping and treatment problems alongside the structural review. Wet-well entry requires confined-space procedures and atmospheric testing; smell cannot establish safe conditions. Ask the repair contractor to document substrate preparation and coating compatibility before work begins.
How Luften handles it
Luften offers a free on-site survey and written treatment recommendation. Its managed service programs use metered chemical dosing, with service checks of dose rate, reservoir level, and pit condition. Documented visits help building staff track treatment operation. Treatment management does not replace a structural assessment or concrete repair.
Wastewater hydrogen sulfide controlFrequently asked questions
- Can I repair without taking the station offline?
- Pump-around setups allow recoating without shutdown but add significant cost.
Have this problem in your building?
Free on-site survey across NYC and the tri-state area.
Request a survey