Your well water smells like rotten eggs, especially hot water. You stopped noticing it months ago, but the guests at Thanksgiving did not, and your kids' friends will not drink from the tap. Lift the lid and there is slime in the toilet tank (rusty-brown, gray or black) that grows back a week after you scrub it. That pairing, sulfur odor plus slime, is the signature of a Silurian dolomite well in eastern Iowa, and it is exactly what ozone water treatment was built for: an ozone generator, a contact tank and a backwashing filter that oxidize the sulfur, the dissolved iron and the bacteria feeding on both, with no chlorine drum and no chemical pump in your basement. Midwest Water Solutions installs and services ozone systems for wells around DeWitt, the Quad Cities and across Clinton, Jackson and Scott counties, and a free in-home water test is available before you buy.
Rotten-egg water: well, water heater, or bacteria?
Two questions decide the fix before anyone talks equipment.
Is it every tap, or only the hot water? Run the cold kitchen tap into a glass and smell it. If the cold water is clean and only the hot water smells, the well is innocent. Inside a tank water heater, the magnesium sacrificial anode rod reacts with naturally occurring sulfate-reducing bacteria and makes hydrogen sulfide right there in the tank. An ozone system on the well line will not fix that. The fix is an aluminum-zinc or powered anode, a tank flush and a sanitizing cycle. We cover the whole diagnosis in why well water smells like rotten eggs. If both hot and cold smell, and the cold is worst first thing in the morning after the water has sat in the pipes, the gas is coming up the well with the water.
Is there staining or slime too? Orange or rust stains in the toilet and tub alongside the smell mean dissolved iron is riding along with the sulfur; the staining chemistry and the single-tank options are on our iron filter page. Slime is a different tell. Rusty-brown, jelly-like growth in the toilet tank, black or gray slime in the tank or on aerators, and a musty or oily sheen on the water mean iron bacteria or sulfur bacteria have colonized the well casing, the pressure tank and the plumbing. They are not a health hazard on their own, but they feed on iron and sulfur, produce more hydrogen sulfide as a byproduct, and clog screens, valves and softener resin. An oxidizer that also kills them is the only thing that stops the cycle.
The geology explains why this is so common here. Private wells on the uplands around DeWitt, Welton, Low Moor and Grand Mound draw from fractured Silurian dolomite 100 to 300 feet down, where low dissolved oxygen keeps iron in solution until it hits air. Grand Mound's municipal wells in that same rock run about 1.7 mg/L iron and 0.10 mg/L manganese according to Iowa DNR, nearly six times the 0.3 mg/L iron guideline, and a private well next door gets the same water. Raw well water in the Eldridge area carries 0.7 to 2.1 mg/L ammonia, which is why some acreage wells there read as musty or ammonia-like rather than purely eggy; the test tells those apart. Across the river, Fulton's own Well 4 pulls 1.3 to 1.5 mg/L iron and about 0.6 mg/L manganese out of the Mississippi bottoms before the city's plant strips it out; a shallow sand-and-gravel well on Cattail Road gets it all.
How ozone water treatment works
Ozone is O3: an oxygen molecule with a third atom bolted on that it badly wants to give away. That extra atom is what does the work. A corona-discharge generator makes ozone on site from the air in your mechanical room, and every time the well pump runs, a venturi injector on the line pulls that ozone into the water stream. Some systems feed the gas into the contact tank through a diffuser instead; either way, nothing is delivered and nothing is refilled.
The contact tank is where the reactions happen. Water gets a few minutes of retention with the ozone, and in that time hydrogen sulfide is oxidized to odorless sulfate and elemental sulfur, dissolved ferrous iron becomes ferric iron particles (rust you can filter), and manganese drops out as manganese dioxide. Bacteria cell walls rupture on contact. Excess ozone vents off the top of the tank through an off-gas line, and whatever is left in the water breaks back down to ordinary oxygen within minutes, so nothing reaches your faucet but oxygen and water.
The backwashing filter is the third piece, and it is not optional. Oxidation turns dissolved contaminants into particles; a tank of catalytic filter media with a control valve on top catches them, then every few days it reverses flow and flushes the accumulated rust and sulfur to the drain. Skip the filter and you have traded a smell for rusty water.
Sizing is the part that separates a system that works from one that only works at a trickle. Sulfur demands several times the ozone dose per ppm that iron does, so a well with 2 ppm of hydrogen sulfide needs a very different generator than a well with 2 ppm of iron. We size from the actual ppm numbers and from the pump's flow rate in gallons per minute, so the smell is gone with two showers and the washer running, not just at the kitchen sink.
Ozone vs air-injection vs chlorination vs UV
Ozone is not the only way to oxidize a well, and it is not always the right one. Here is how we think about it.
Air-injection iron filter. One tank, a pocket of air trapped at the top, water falling through it, catalytic media underneath, a backwash every few days. This is the iron and sulfur filter most people price first, and for moderate iron and light sulfur on a well with decent flow it is the simplest system that truly works. Its limits are heavy sulfur, manganese, and bacteria: slime fouls the air pocket and the media, and air alone does not kill what is growing.
Chlorination with retention and filtration. A chemical feed pump doses chlorine, a retention tank gives it contact time, a filter catches the solids, and usually a carbon filter follows to take the chlorine taste back out. It handles the heaviest loads and it leaves a residual in the plumbing, which matters when a well has a confirmed bacteria problem. The cost is a solution tank to refill, a pump to maintain and a chlorine taste if the carbon stage lags.
Ozone. A stronger oxidizer than chlorine, it handles sulfur, iron, manganese and the slime-forming bacteria in one contact tank with nothing to buy. The honest limitation is the flip side of its advantage: ozone leaves no residual. It treats the water as it passes through, and it does not keep protecting the pipes downstream. A well with a lab-confirmed coliform or E. coli hit needs continuous disinfection (chlorination or UV), and we will say so rather than sell an ozone system as a bacteria cure.
UV. People ask about ozone vs UV water treatment as if it were a choice, and it usually is not. UV disinfects and does nothing else: no smell removal, no iron, no staining. It also needs clear water, because iron and turbidity shield bacteria from the lamp. The common stack on a problem well in this area is an ozone or air-injection filter first, a water softener second, and UV last if the county lab says bacteria are present.
What an ozone system needs
An ozone install has more pieces than a softener, and each has a job.
- The generator and air prep. Corona-discharge cells make ozone from dry air; Iowa basements in July are anything but dry, so a good system includes an air dryer or desiccant cartridge that gets checked at annual service.
- The venturi injector and check valves. The injector pulls ozone in as water flows past. Check valves on that line keep water from backing up into the generator. That is the single most common failure on a neglected system, and the first thing we look at on a service call.
- The contact tank with an off-gas vent. Retention time is what lets the chemistry finish; the vent lets excess ozone escape safely.
- The backwashing filter and the drain. The filter's control valve needs enough flow to lift and rinse the media during backwash. A low-yield well or an undersized pump changes the tank diameter we specify, and the backwash line has to reach a legal drain. On a septic acreage, that is a question we answer before the install, not after.
- Placement ahead of the softener. Iron and oxidizers both foul softener resin. The contact tank and filter come first so the softener sees clean, ozone-free water.
Worth knowing
Maintenance is light but not zero: an annual check of generator output, desiccant, check valves, the filter's backwash frequency and the contact tank, plus a retest of the water. We do that on every brand of ozone and oxidizing system, including ones we did not install.
Where we install
Midwest Water Solutions is based just east of DeWitt and installs ozone systems on private wells throughout Clinton, Jackson and Scott counties and on the Illinois side of the river: the farm and acreage belt around DeWitt, Welton and Grand Mound; the rural wells south toward Eldridge, Long Grove and Park View; Jackson County karst country up to Maquoketa, where shallow wells go turbid after storms and the free county bacteria test matters as much as the smell; and the Fulton Township and Cattail Road bottoms outside Fulton. Farm shops, ag buildings and small commercial accounts on wells get the same approach as a house.
If your well water smells like rotten eggs, the free in-home test is a no-cost way to find out why, and Carson will tell you whether the answer is an anode rod, an air-injection filter or an ozone system. Already know you want ozone? Ask for the estimate. Call (563) 221-9009 or request a free estimate.