GUIDE

Does Hydrogen Sulfide Corrode Pumps, Pipes and Wet Wells? Yes. Here Is How.

Hydrogen sulfide (H2S) gas corrodes concrete and steel indirectly: it dissolves into the moisture film above the waterline in a wet well, a manhole or a pipe crown, and bacteria living in that film oxidize it into sulfuric acid, the acid that does the actual damage. The industry term for that two-step process is microbially induced corrosion. The acid eats concrete first, leaving exposed aggregate and a pitted surface, then moves on to steel ladders, rails, pump housings and impellers, and even the wiring inside an electrical box. Coatings, liners and ventilation slow the damage, but only preventing H2S upstream, before the wastewater ever reaches the wet well, stops the acid from forming at all. DRP Accelerator itself is not an oxidizer and does not attack metals; it is consumed by the bacteria it feeds. This guide covers what the corrosion actually eats, how to spot it early, what protects equipment, and how the protection options compare.

The gas does not eat metal directly. The acid it becomes does.

Hydrogen sulfide gas becomes corrosive when it dissolves into the moisture film on concrete and steel above the waterline in a wet well or a sewer pipe.
Bacteria living in that moisture film oxidize dissolved hydrogen sulfide into sulfuric acid, a process the wastewater industry calls microbially induced corrosion.
Sulfuric acid dissolves the cement paste in concrete, leaving the aggregate exposed and eventually eating through the crown of a pipe or the walls of a wet well.
Steel ladders, rails, pump housings, impellers and wiring inside electrical boxes are all vulnerable to the same acid film.
Coatings and liners slow hydrogen sulfide corrosion but do not stop the gas that causes it from forming.
A pump moving thick grease and settled solids draws more current than a pump moving clear wastewater.
An inorganic compound that is not an oxidizer and does not attack metals cannot be the source of pump or pipe corrosion caused by sulfuric acid.

Published September 24, 2026

What happens when hydrogen sulfide meets a wet surface?

Hydrogen sulfide (H2S) gas does not corrode concrete or steel directly, not as a gas moving through open air. The corrosion starts when that gas dissolves into the thin film of moisture that coats a pipe crown, a wet well wall or the underside of a manhole lid above the waterline. A separate population of bacteria lives in that moisture film, the kind that thrive above the water rather than in it, and they oxidize the dissolved hydrogen sulfide into sulfuric acid. The industry term for this two-step process, gas dissolving into moisture and bacteria turning it into acid, is microbially induced corrosion. It is biological before it is chemical: remove the gas and the acid-forming bacteria have nothing to convert.

This matters for where a facility looks for damage. The corrosion is not happening in the flowing wastewater below the waterline. It is happening above it, on any surface the gas can reach and moisture can hold, which is why a wet well can look sound below the water and badly eaten above it.

What does hydrogen sulfide corrosion actually eat?

Sulfuric acid formed this way attacks whatever sits above the waterline in a wet well, a manhole or a stretch of concrete sewer pipe carrying septic flow. Concrete goes first: the crown of the pipe and the upper walls of a wet well lose their cement paste and leave the aggregate exposed, then pitted, then gone. Steel corrodes too, ladders, rails, guide rails, pump housings and impellers all pit and thin under the same acid film. Wiring inside electrical boxes and conduit fittings corrodes from the inside, which is how a gas problem becomes an electrical fault. Roofing over a wet well or a lift station building corrodes from underneath, and even a fence near a vent stack can show the same pitting and staining if gas vents past it often enough.

How do you spot it before it becomes a structural repair?

Concrete crown loss and exposed aggregate on the upper walls of a wet well or a manhole are the clearest signs, and progress from a rough, sandblasted-looking surface toward exposed rebar over time. Orange and black staining on concrete or steel marks where the acid has been active. Pitted, thinning steel on ladders, rails and pump components is a mechanical sign, not just a cosmetic one. Electrical faults that trace back to corroded wiring inside a junction box are a less obvious sign of the same gas problem, playing out on copper instead of concrete. An operator who inspects a wet well and sees any of these should treat it as an H2S question first, not only a structural one.

What protects equipment from hydrogen sulfide corrosion?

Coatings and liners on concrete buy time. They slow how fast the acid eats through, but a coating does not stop the gas from forming, and it does not reach bare metal at every joint, fitting or unlined surface. Ventilation moves gas out of a confined space and dilutes what is in the air, which helps worker safety and can slow the corrosion rate, but it does not change how much hydrogen sulfide the wastewater is generating in the first place. The only way to stop the acid from forming at all is to keep the gas from forming upstream, in the water, before it ever reaches a wet surface. That is a different kind of protection than a coating or a fan: it addresses the water, not the structure above it. For a wet well or a collection system where septic wastewater is the real cause, that is worth reading further on H2S removal and prevention.

Does a grease-loaded wet well affect pump load?

A wet well carrying heavy grease and thick, settled solids makes a pump work harder: the motor draws more current moving thick, viscous material than it does moving clear water. At a dairy we treated, the pump amperage fell once the grease and solids sitting in the wet well broke down, because the pump was moving thinner water afterward. That is a mechanical side effect of the same biological process that prevents H2S. Bacteria supplied with usable oxygen digest fats, oils, grease and organic solids, and a wet well that used to hold sludge and grease holds wastewater instead.

Does DRP Accelerator itself corrode anything?

No. DRP Accelerator is not an oxidizer and does not attack metals, concrete or coatings. It is an inorganic compound that carries usable oxygen to the bacteria already living in the wastewater, and the bacteria consume it as they use that oxygen. Nothing of the accelerator is left in the water to reach a pump, a pipe or a wet well wall downstream. What reduces the corrosion is not the compound acting on metal, it is the bacteria that never have to scavenge sulfate in the first place, so the sulfide, and the sulfuric acid it becomes, is never made.

How do the protection options compare?

Coatings, liners and ventilation each have a real place, and for a structure that already has extensive corrosion damage or limited water and power for a dosing point, they may be the only practical option in the near term. Where a site can reach the wastewater far enough upstream, addressing the gas at its source removes the reason the other options exist at all.

Option	What it does	What it does not do
Coatings and liners	Physically separate concrete or steel from the acid film	Stop the gas from forming, or reach every joint and fitting outside the coated area
Ventilation	Moves gas out of a confined space and dilutes the air	Change how much hydrogen sulfide the wastewater generates upstream
Preventing H2S upstream	Supplies the bacteria already in the wastewater with usable oxygen so sulfide is not made	Repair damage that already exists before treatment starts

Summary

Hydrogen sulfide gas corrodes concrete and steel indirectly: it dissolves into the moisture film above the waterline, and bacteria there convert it into sulfuric acid, a process called microbially induced corrosion.
The acid eats concrete crowns and walls, steel ladders, rails, pump housings and impellers, and electrical wiring, and shows up as exposed aggregate, staining, pitting and electrical faults.
Coatings, liners and ventilation slow the damage; only preventing the gas from forming upstream, which is what DRP Accelerator is built to do without acting on metal itself, stops the acid from forming at all.

COMMON QUESTIONS

Straight answers.

Does hydrogen sulfide actually corrode pumps and pipes?+

Yes, hydrogen sulfide gas corrodes pumps, pipes and wet well structures, though not by touching metal directly as a gas. It dissolves into the moisture film above the waterline, and bacteria in that film convert it into sulfuric acid, which is the acid that eats concrete and steel. The process is slow enough that it often goes unnoticed until an inspection or a rehabilitation project finds the damage.

What is microbially induced corrosion?+

Microbially induced corrosion is the industry term for the process by which hydrogen sulfide gas becomes sulfuric acid inside a sewer or a wet well. Bacteria living in the moisture film above the waterline oxidize dissolved hydrogen sulfide, and the resulting acid attacks concrete and steel. It is a biological process before it is a chemical one, since it depends on that bacterial population being present and fed by the gas.

What does hydrogen sulfide corrosion damage besides concrete?+

Hydrogen sulfide corrosion damages more than concrete. Steel ladders, rails, pump housings and impellers pit and thin under the same acid film, wiring inside electrical boxes corrodes from the inside, and roofing over a wet well or a lift station building can corrode from underneath. Even a fence near a vent stack can show pitting if gas vents past it often enough.

How can an operator spot hydrogen sulfide corrosion early?+

An operator can spot hydrogen sulfide corrosion early by watching for crown loss and exposed aggregate on concrete, orange and black staining, pitted steel on ladders and rails, and electrical faults that trace back to corroded wiring. A wet well that looks sandblasted on its upper walls is showing the same damage. Catching these signs early turns a structural emergency into a planned repair.

Do coatings and liners stop hydrogen sulfide corrosion?+

Coatings and liners slow hydrogen sulfide corrosion but do not stop it, because they protect a surface without changing how much gas the wastewater is generating. Every joint, fitting or unlined surface a coating misses is still exposed to the acid film. Preventing the gas from forming upstream, before the wastewater reaches the wet well, is the only way to stop the acid from forming at all.

Does DRP Accelerator corrode pumps or other equipment?+

No, DRP Accelerator does not corrode pumps or other equipment. It is not an oxidizer and does not attack metals, and it is consumed by the bacteria it supplies with oxygen, so nothing of it is left in the water to reach a pump or a pipe downstream. What reduces the corrosion is the hydrogen sulfide that never forms in the first place, not the compound acting on metal.

Does treating hydrogen sulfide also help a pump's motor load?+

Treating hydrogen sulfide can help a pump's motor load when the same wet well also carries heavy grease and settled solids, because a pump moving thick material draws more current than a pump moving clear water. At a dairy we treated, the pump amperage fell once the grease and solids in the wet well broke down. That is a side effect of the biological process, not a guaranteed result at every site.

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