The use of bleach in pressure washing

The Use of Bleach in Pressure Washing

One of the most asked questions as a pressure washing contractor is about the use of bleach when pressure washing a house. No sane homeowner wants to do something harmful to their home or the environment on purpose. This question is very understandable with so much information, misinformation and disinformation presented as marketing by various chemical manufacturers. When a product claims to not only do a job, but also do a job without causing harm that another product does, it will raise questions such as this for me to answer for homeowners needing some understanding.

As a rule, manufacturers of materials that comprise the building of your home's exterior have specific recommendations for cleaning. That includes everything from different types of vinyl, brick, stucco, dryvit, aluminum and painted siding made of wood or cement and various roofing and decking materials as well. The general rule is to clean those materials however the manufacturer recommends. In doing so, there will be no harm done. Of all the materials used for building a home, cleaning with the use of high pressure is the least recommended, and that is only with certain types of stain removal on very limited materials. Bleach is most often recommended for removal of mildew stains along with the use of low pressure rinsing.

A quick lesson on bleach. The active ingredient in bleach is sodium hypochlorite. That ingredient is used from anything such as cleaning clothes and swimming pools to dental and hospital cleaning for fast and ensured disinfecting purposes. It is even used for treating the water we drink and yes, safe and effective low-pressure cleaning as well.

Is bleach environmentally safe? In the control of a technician trained in the use and handling of sodium hypochlorite, it most definitely is environmentally safe. Yet, just like most anything else, there can be too much of a good thing. There is little question to the dental assistant or water treatment operator as to the competence of their abilities, as well there should be little to no concern of the care and attention your pressure washing contractor should exercise while using it to make your home's exterior sparkling clean.

What about the exterior cleaning alternatives to bleach? Please bear in mind the nature of business for chemical providers is to ultimately make a profit. Marketing in it's very being can often times be misleading and confusing. Many chemical manufacturers have taken the eco-friendly thought and used it for promotion of their cleaners while defaming bleach for cleaning mildew stains. In the name of environmental friendliness, they promise results that sometimes won't be visible for months, hoping you will accept the delay in visible difference, if they even come at all. For me, even as an experienced and respected exterior cleaning specialist, it all boils down to using what is guaranteed to work within the manufacturers recommendations. As much as I love what I do, with as many satisfied and loyal customers as I have acquired over time, I still have role models in this industry that have led the way before I arrived. In my willingness to learn from leaders across the country in this industry as well as my own research otherwise as to the countless uses of sodium hypochlorite, I have a sound confidence there is simply no better alternative than the proper use of bleach while pressure washing a home's exterior to remove mildew stains.

The Ultimate House Wash

5013 Bowline Court
Southport , North Carolina 28461
Phone: (910) 278-1137
Email: [email protected]

Contact Us.

John Marston

Pressure Washing Rig UHW

The Ultimate House Wash - 5013 Bowline Court - Southport - North Carolina - 28461



46 Responses to The use of bleach in pressure washing

  1. Hello John, happy New Year. Could not agree more with your comments as I to saw the light
    and wash homes with simple cheery or elemonator as my soap and bleach to kill the mold and
    mildew. My percentage to the wall is less than 1% sodium hypoclorite and you are right prewet all plants, shrubs, grass never had an issue hurting anything.Anyone who has damaged
    or killed plants,etc simply do not know how to use sodium hypoclorite in proper dilutions.
    Google Window cleaning Halifax and find Bill’s Window Cleaning and Pressure Washing ad I
    discuss this issue in a video. Cheers!

  2. The important thing to remember is, as you said, that “there can be too much of a good thing.” I used pure bleach once to clean an absurd amount of mold from a ceiling. It worked really well, but got me sick. Pressure cleaning is more effective with the right amount of bleach, and it won’t have any consequence on the environment.

    • Completely agree. Thing about using bleach on exteriors, is pressure washing technicians will rinse the the mildew away after treating it first. On interiors, it’s a completely different beast. I usually recommend removing the surface that the mold is attached to altogether if it’s built up as bad as you say. The mold may be treated, but the matter itself will still remain and act as a breeding ground for regrowth. It’s also not safe with that much inside.

      Thanks for visiting and commenting.

  3. I use actual Clorox. But what is the best way to spray it on a large and tall 2 story home? Also, is the long tele-wands the best way to get up to the tall house? Or is there a better method. The tele-wands can be so tiring and difficult.

    • Telescoping wands, often referred to as yellow noodles in the pressure washing industry, are a sure way to give yourself a great shoulder and arm workout.

      The best way to get your house washing soap up to the higher areas is with safety in mind first. If the yellow noodle keeps you off of a ladder, then it’s better than nothing.

      The 3 most common ways pressure washing contractors get soap to higher areas is by either down-streaming, x-jetting or direct application with a chlorine resistant pump. For simple disinfection and removal of mildew stains on siding and trim, down-streaming is my preferred method. What is meant by down-streaming is, soaps are introduced into the system after the pump part of the pressure washer through the use of a chemical injector. The second part of what makes down-streaming effective is the use of proper tips on the end of your pressure washing wand. With the proper tips, you can then apply soaps to those higher peaks while still standing on the ground. A Pressure Washing Company - Downstreaming This image shows soap being applied via down-streaming around 30 feet high with less than only 100 psi.

      If you would like to learn more about down-streaming and how to get set up doing it yourself, feel free to ask and I will be happy to help.

      • I have a residential, non-bleach use, 3100 psi pressure washer. I’ve tried to get soap (using the standard soap tip) to the mildewed peaks over my garage. Can’t do it. Can’t reach it either with the standard 0 degree spray tip. How do you do it? And what is down-streaming? Help please!! I do have an 18″ extension wand. Got any ideas for better distance washing too? Curt Hawks; [email protected]

      • I’ve been interested in downstreaming. I have a little experience from working with a guy powerwashing decks and houses but we always used a 50/50 solution in a garden sprayer followed by a couple guys with with a brush and the powerwasher. Can downstreaming be done with the soap tips that come with the machines or is it much better with the custom tips.( Something like 040? I think I read).. I have a powerwasher that I use now but it’s a low gpm machine

      • I’m interested in doown streaming. And would like to get setup as well. As well as any info on soft washing. Thanks!

      • i was told buy the technician repairing my pressure washer not to use bleach in pressure washers it damages the O rings and voids pump warranty is that true?

        • This is likely good information your technician is giving you. The best way to use bleach with a pressure washer is to introduce bleach into the system after the pump rather than before. A downstream injector, x-jet or m-jet are the most common ways to bring soap that includes bleach into the line. Watch this video to get an in depth understanding of how downstream injection works. This should help you keep your pressure washer working much longer as well as make your job far easier and safer.

  4. Hi. My name is Jason and I live in Florida. As you can imagine mold and algae here runs rampant here. I have been traveling the net trying to learn as much as I can about the proper use of Sodium Hypocrite (aka. Clorox)and the proper mix ratio for as small as 5 gallons. To no avail I have not found a recipe for something that small. Any advice? Also I am using a down stream injector like the one in the picture. Anything you can send I would much appreciate it. Thanks.

  5. Thank you jon for taking your time out to write us these tips. I know pressure washing homes all day then coming home to give us tips isnt easy but you manage is thank you!

    • Soap as a whole is made up of different parts. For pressure washing, I use a soap with ingredients that emulsify all organic stains. In other words, the soap makes all organic matter such as mildew, dirt, spider webs, etc lift off of the surface in which it is attached and become one with the soap and water mixture. When this happens, light pressure is all that is necessary for rinsing everything away on most surfaces. This low pressure method makes it more likely that little or no damage to surfaces such as wood, vinyl, composite decking or painted siding will occur. Surfaces such as concrete or brick will often require higher pressures to provide a truly clean surface. Reason being is those concrete or brick surfaces are far more porous. Contaminates are less likely to be able to just rinse away without higher pressure. Those surfaces are also far more durable, and less likely to be damaged with higher pressure. Care should be taken even so, whereas most anything can be damaged with high pressure washing methods and no training.

  6. I live in Victoria BC Canada where people are terrified of bleach. I find it rather funny as i have always been a user of bleach, for it’s many, many uses.

    Nice to see there is someone who agrees and is not afraid to stand up and say something about it.

  7. im,just about to start soft washing,im going to use a power washer with a soap pipe,
    my mix will be 3 water 1 hyro,@15%,using a 24ft adjustable lance,
    leave on for 15 mins the rince off with water,any grass/plants will get a covering with water before and after i do the house,any comments good or bad would be greatfull,thnx
    “A KLEAN” in the uk

  8. Hi quick question, is there any non toxic alternatives that you would ever use on a house when soft washing. Thinking of starting up a pressure washing business here in Australia and would like to offer an alternative to Sodium Hypocrite for customers that dont want any chemicals used. I no Sodium Hypocrite is safe when used properly and will work best, unfortunately there’s plenty of people out there that wont want the job done as soon as they here bleach.

    • Hi Steve. Thanks for taking the time to ask my thoughts on this.

      I hope I can help, but this won’t be a simple answer that you may be looking for. You touched on quite a few items, and I would like to cover them.

      There is a solution. It is not the easy way, but it is the right way. It will involve integrity, self learning through research and educating others in the process. It will also take a realization that starting up a pressure washing business will provide you with many obstacles far greater than the debate of whether to use bleach or not.

      First of all, bleach is not considered toxic, even if ingested. I’m not saying it’s good to use for washing down that steak dinner or to breath in after a long run, but who does that anyway? 🙂 It all boils down to the way in which bleach is used. The one responsible for handling it determines the effects the bleach will have. As a professional pressure washing contractor, one should be expected to be able to practice safe handling methods to both persons and the environment.

      Water is a chemical. H2o. Oxygen o2. Carbon Dioxide Co2. I’m no chemist by any means. Even so, when conversing and a request comes up for ‘no chemicals’ to be used, it can be a head scratcher sometimes. I’ve said it before, and it’s just a fact of something we are up against in this industry. Manufacturers of cleansers of all sorts do all they can to promote their own product while defaming some other or just for nothing else other than to promote their own brand or blog. Even if it is the same thing but with a different label. These manufacturers target a group labeled as DIY or do it yourselfers with a constant onslaught of misinformation and disinformation. This targeted group genuinely cares about their cleaning enough to ask around and see what is best. Who can blame them? Little guys like us get to compete with that. Now, (emphasis added) this is where, as an operator of a business, you will have a choice of your own to make. Just as bad or even worse is when some professional users of those products (ie. a professional pressure cleaning company) enable the mis-representation of what is being used, even after learning the truth, to promote their own services. Do you want to just go with the flow of the next best thing and mislead what you offer as well, or do you take this newly found understanding and provide an honest service at a fair price for all parties involved? It may sound like a simple decision when presented in this way but yes, I have witnessed another pressure washing contractor brag about their non-use of bleach while pulling out of a Clorox bottle. When asked about it the response was, “It’s not bleach, it’s Clorox!’. I still find humor in this memory.

      As a professional, you are being sought after for your knowledge and experience. You are being sought after for your trustworthiness and work ethic more than anything I believe. All you can do is offer whatever your service is, promise to do your best and fix it if you make a mistake. What I am trying to say is, you will be looked upon to be the professional. You should know what will work best. Imagine me trying to tell my doctor how I think he/she should do things…. It’s okay if some people don’t want what you are offering. There is no one company that is for everyone.

      You say there plenty of people that won’t want the job done as soon as they hear the word bleach. There are plenty of people that will still, and in my area I receive a great many requests to use it or nothing else. This ties into your presentation of yourself, your company, what direction you are going to go with it and how much you are willing to sacrifice. It is not an easy thing to do. Your first years, you may very well have done better working at a grocery store. The payoff may never come if you can’t or won’t stick with it. 80 hour weeks and net income of less than if you worked 40 hours at fast food.

      Suggestion: Work for another company for a while, learn all you can. Become confident in your knowledge and abilities. I mean this in the nicest possible way.

      Feel free to ask away or respond.

  9. When applying bleach (ratios correctly) onto siding over a dormer or gable with a roof underneath, will that run off discolor the roof and look uneven?

    • The type and condition of roof will need to be known to say for sure. If the roof is cedar, chances are very great there will be a change in appearance when applying soap to the siding above the roof. If the roof is metal, asphalt or tile and full of organic staining, there may be an area of the roof that appears clean from the runoff initially applied to the siding.

      It would be a very special circumstance for this to be a concern. ie, Cedar roof. A way to mitigate this if it is a concern is to have a second person on site keeping the roof soaked by spraying it constantly with water at very low pressure. Wetting the roof before, during and after the application of soap. Even then, no promises. Another alternative is to cover the roof with plastic and still do the pre, during and after wetting with water just to be sure.

      Hope that helps

  10. Very good reading. I’m 60 and just getting started while I hold down my full time job. This will be extra money when I retire in 5 years. I’m in no rush so I’m watching videos and a lot of reading on soft washing. Thank you

  11. Thanks for publishing this awesome article. I’m a long time reader but I’ve never been compelled to leave a comment.
    I subscribed to your blog and shared this on my Facebook.
    Thanks again for a great post!

  12. How do you handle oxidized vinyl siding? Please don’t say a complete scub down. I’ve heard of using “ox” but have not ever used a acid.

  13. John,
    Hello. I spend lots of countless hours reading articles on the web. I myself own my own pressure washing business here in Eastern Iowa. The question I have is when downstreaming what is your mix ratio? The less bleach I can use the more money I can make. What works for you? I am using 13% sodium hypochlorite. My supplier tells me it’s actually 15% but guaranteed at 13%. Always wonder what the true ratio is coming out of the tip when downstreaming.

    • Use 2 buckets. One bucket @ 10 gallons, the other bucket @ 1 gallon.
      Put the downstream injector into the 1 gallon bucket. Spray water from your pressure washer into the 10 gallon bucket. When the 1 gallon container that the injector is in is empty, see how much water you have added to the 10 gallon bucket. Do the math from there.

      All it takes to disinfect mildew such as you will see on vinyl siding is a little less than 1% sodium hypochlorite.

  14. Thank you for sharing this information with us John. I work with a family owned pressure cleaning business here in Miami and I always seem to learn something new every day. I just bookmarked this blog and will be looking out for any new blogs you post! Thank you again!

  15. I am new to power washing and i have a vinyl siding house to wash with green mold from trees on it. On a scale from 01 to 10 (with 10 being the worse) i would rate the visible presence of the mold at a 03 to 04.
    I plan on down streaming using a 12% liquid chlorine from the pool store.
    My dilution ratio will consist of a 03 to 01 (three gallons of water to one gallon of liquid chlorine) which will be drawn from a 15 gallon barrel strapped to a dolly. Keeping in mind water will be pulled from my tank will this be a strong enough mix to cut the mold from the vinyl siding?
    I know there are products out there like Roof Snot but what would be the best household type of soap/detergent to add to the mix so it will foam up and cling to the vinyl surface?

  16. Hi John,
    I just ran across your website. I really appreciate your helpful advice! I’m just getting into pressure washing and low pressure house and roof washing. I have everything to learn and do not want to go any further than I “think” I know what what I’m doing. I have 4 gpm/4000 psi belt drive and 4 gpm 3500 psi direct drive in pressure washers. I have a Fatboy system from PressureTek.
    Let me ask you honestly, do I even need the Fatboy system, or can I get the same results by downstreaming, and then washing w/low pressure from a pressure washer? Will the downstreaming be as effective on roofs as a Fatboy system?


    • The Fatboy system from PressureTek is a great tool for exterior cleaning. It allows for a method referred to as ‘direct application’. The Fatboy allows you to apply a mixture stronger than would be possible via down-streaming or x-jetting to effectively clean a roof among other things as well.

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