Soft Washing and Milwaukee-Area Water Quality
Where I stand on soft washing in the Milwaukee area
To be clear where I am coming from: I don't have anything against soft washing. It works, it has its place, and we can do it at EcoWash when it's the right call for a house.
However, I'm not comfortable with how much chemical goes into a typical soft wash in Milwaukee. I'm even less comfortable with how careless a lot of crews are about where that chemical ends up.
Most of the time, the runoff goes down the driveway, into the gutter, and into the storm drain at the curb. In the Milwaukee area, that storm drain usually leads to a creek or river, and from there a lot of it ends up in Lake Michigan. That's the same lake Milwaukee drinks from, and as of a few years ago, so does Waukesha. As someone who does a lot of fishing in Lake Michigan, I really do not like the idea of even more chemicals making it into the lake.
I wanted to write this so homeowners know what to look for, because most people never think about where that water ends up. Soft washing companies sell their service as the greatest thing, better than a pressure wash. But one question almost always gets left out: if you live near a creek, a river, or the lake, is the amount of chemical worth the risk?
How much chemical are we talking about?
The "soft" in soft washing is about water pressure. It has nothing to do with the chemicals.
The main ingredient in almost every soft wash mix is sodium hypochlorite (SH). Most crews buy it at 12.5% strength, which is roughly twice as strong as the bleach in your laundry room.
It gets watered down before it goes on the house, but roofs and heavy algae get a much stronger mix than siding does.
Crews add surfactants (it can be any dish soap) so the SH clings to the wall instead of running straight off. That helps it work, but it also means foamy, bleachy water coming off every surface of the house.
Now multiply that across a whole house, or a whole roof draining through the gutters. That's a lot of chemical landing on your property. Some of it soaks into the ground, and some of it breaks down, but the rest has to go somewhere.
Where it goes in Milwaukee and Waukesha
Milwaukee County
Most of the Milwaukee area has separate sewers. Your toilet and sink drain to a treatment plant, but the storm drain at the curb is a different pipe. According to MMSD, the storm water in those separate systems gets released to nearby waterways without being mixed with sewage, and it isn't treated along the way.
That means the Menomonee, the Milwaukee River, the Kinnickinnic, the Root River, and all the little creeks that feed them. Every one of them ends up in Lake Michigan.
There's one exception. About 6% of MMSD's service area, all in the City of Milwaukee and Shorewood, has combined sewers, where storm water and sewage share one pipe and normally go to the treatment plant. But when it rains hard, those pipes overflow straight into the rivers and the lake. That happened twice this year (2026) alone, including a six-day overflow in April that released 2.7 billion gallons.
Waukesha County
Waukesha is a little different. Much of the county drains to the Fox River, which runs south through Waukesha and into Illinois, not toward Lake Michigan. The eastern side of the county, around Brookfield, Elm Grove and Menomonee Falls, drains toward the Menomonee and on to the lake.
The Fox has been under the microscope for years. Back in 2000, the DNR named eight communities, including the City of Pewaukee, as significant sources of storm water pollution to the Upper Fox River.
And here's a detail that caught my eye. When Waukesha County inspects its storm sewer outfalls and sees foam or a strange color, two of the things it tests for are chlorine and detergents. That's exactly what's in a soft wash.
The rules
Waukesha County has an ordinance prohibiting illicit discharges to its storm sewers, and 29 municipalities in the county are required to have their own. Milwaukee-area communities work under the same state stormwater permits. The bottom line is the same everywhere: storm drains are for rain. Wash water doesn't belong in them.
What careless crews skip
Doing this right isn't complicated. It just takes extra time and some extra gear, and that's exactly why some crews don't bother. Here's what I see skipped most often:
Covering the storm drain. A mat or a few sandbags at the curb takes five minutes. Plenty of crews never do it.
Dealing with the downspouts. On a roof job, the gutters collect the strongest runoff of the day and dump it all in one spot. A good crew bags or diverts it.
Soaking the plants. Plants that are watered before, during and after the wash take up far less bleach. Dry plants drink it right in.
Mixing to the surface. Some crews run one strong mix on everything because it's faster. Siding doesn't need roof strength.
What that costs you
When a crew cuts these corners, it's your property that pays for it.
Your landscaping. Bleach breaks down plant tissue the same way it breaks down mold. Burned shrubs and dead patches of lawn can show up days later, long after the crew is gone.
Your name on the complaint. If wash water runs into the street, the neighbor or the city sees it coming off your house. You're the first one they'll ask about it.
Your liability. Soft washing means ladders, roofs and wet surfaces. If an uninsured worker gets hurt at your place, that claim can end up on your homeowner's policy. It's worth a call to your insurance agent before you hire anyone.
How we handle it at EcoWash
Our approach is simple: use the smallest amount of chemical that will actually get the job done. Most houses don't need a full soft wash. In my experience, on nearly every home we've worked on, maybe half of the north side needs chemical at all.
When we do use sodium hypochlorite, we soak the surrounding area before application, dilute heavily so the concentration stays low, and make up for it with extra applications or longer dwell time to let the chemical work. It adds a little time to the job. We're fine with that.
Questions to ask any soft washing company
Whoever you hire, ask these before they start:
Where does the runoff go? If the answer is "down the drain," find someone else.
Do you cover storm drains and deal with the downspouts?
How strong is the mix you'll use on my house? A good crew can answer this without guessing.
Can I see your certificate of insurance? Liability and workers' comp, with current dates.
If you're in Milwaukee, Waukesha, or anywhere in between and want a crew that takes this seriously, get a free estimate from EcoWash. We'll tell you straight whether your house even needs a soft wash.
Frequently asked questions
Does soft wash runoff reach Lake Michigan? It can. In most of the Milwaukee area, storm drains empty into local creeks and rivers like the Menomonee, Milwaukee and Kinnickinnic, which all flow to Lake Michigan.
Where does stormwater go in Waukesha? Much of Waukesha County drains to the Fox River, which flows south into Illinois. The eastern part of the county drains toward the Menomonee River and Lake Michigan.
Is it legal to wash soft wash water into a storm drain in Waukesha County? No. Waukesha County and its municipalities have ordinances that prohibit illicit discharges to storm sewers.
Will soft washing kill my plants? It can. Plants that are soaked with clean water before, during, and after the wash usually come through fine.
What should I do if I see a crew washing into a storm drain? Call your city or village public works department. They handle storm sewer complaints in most Milwaukee and Waukesha area communities.
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