Life's Dirty. Clean Easy.

How To Clean A Sidewalk

By Wet & Forget
Find out how to clean a sidewalk without a pressure washer!

A sidewalk is many things: a running track, a chalk canvas, and even a storefront for a lemonade stand. At the end of the day, though, a sidewalk is usually dirty. 

From organic growths like moss and algae to simple, everyday detritus like mud and dirt, keeping your sidewalk clean is manageable when you have the right tools and information at your side. So, check out our guide on how to clean a sidewalk to keep your do-everything walking path free of permanent stains and potential damage. 

What’s Growing On Your Sidewalk? 

While you can remove dirt and mud with a hose, a little bit of Dawn dish soap, and a broom, organic growths can be a little more challenging to tackle. Those dark stains may not always be caused by dirt, but the majority of the time they are actually caused by organic growth.  Knowing what type of growth you’re dealing with is the first step in getting rid of it: 

  • Algae thrive in sunlight, feel slimy, and are usually green or sometimes black or red. 
  • Lichen requires sunlight, have stem-and-leaf-like growths, and are green when wet but can be a variety of colors when dry. 
  • Mold and mildew prefer dark and damp environments, can be slimy or powdery, and are typically black but may also be brown, green, or yellow. 
  • Moss needs sunlight but are often found in shaded areas, have tiny leaflets, and are usually green but can also be black, brown, or yellow. 

Keeping your sidewalk in good structural shape requires removing these growths whenever you spot them. If left untouched, they can make a sidewalk dangerously slippery, cause permanent staining, or even affect the durability of the concrete. 

Wet and Forget Outdoor makes sidewalk cleaning easy.

How to Clean a Sidewalk 

As pernicious as organic growths can be, you don’t need to invest in heavy-duty tools and equipment to remove them from your sidewalk. Instead, you’ll need Wet & Forget Concentrate and a few minutes of free time to get the ball rolling. 

Wet & Forget Outdoor products contain no bleach, acid, or phosphates. This allows the spray to clean gently and over time by working with wind and rain. 

Unlike bleach, which has a high pH level of 13 and can damage outdoor surfaces, Wet & Forget Outdoor has a more neutral pH of 8. This makes it safe to use on almost any outdoor surface, including concrete, stone, or other materials often used in sidewalks. 

For Wet & Forget Outdoor products to be effective, you should use them on days with the right temperature and weather conditions: 

  • A temperature of at least 32 degrees Fahrenheit during application and for at least five hours afterward. 
  • A forecast without rain within four to five hours after application. 
  • A day that’s not too hot or sunny. 

If you find those conditions are met, you can remove your sidewalk of obnoxious and unsightly organic growth. 

We tested Wet and Forget by spelling “GUMP” with the product on the sidewalk to see what would happen!

How to Remove Algae, Mold, and Mildew From a Sidewalk 

If you’re dealing with algae, mold, or mildew, follow these instructions: 

  1. Mix the Wet & Forget Concentrate in a pump up sprayer using a 1 part Wet & Forget to 5 parts water dilution ratio. If you have a one gallon sprayer, add 20 oz (2 ½ cups) of Wet & Forget to your sprayer, then fill the rest with water.  
  2. Spray onto a dry surface until the sidewalk is thoroughly soaked. 
  3. Keep people and pets off the sidewalk until the product has completely dried. The product should take roughly 4-5 hours to dry. 

The spray will work with wind and rain to gently clean the area over time without damaging the sidewalk’s surface. 

Green growths will only need a few days or weeks, at most to see results. Black stains may need a month or two. Incredibly stubborn or long-lasting stains may require at least six months. 

After your first spray, though, you’ll likely only need to apply Wet & Forget once annually. Depending on your climate, humidity, and weather, a single application can keep a surface for up to a year or longer. 

How to Remove Moss and Lichen From a Sidewalk 

Moss and lichen are slightly more complex organisms than algae, mold, and mildew. So, if you identify them on your sidewalk, you’ll have to take a few extra steps to ensure their removal. 

For moss, that means soaking the growth with Wet & Forget Outdoor until it reaches the surface it clings to. Within a few days, you should notice the moss turn brown and curl away from the surface. Then wind and rain will gently wash the moss away. 

For lichen, follow these step-by-step instructions: 

  1. Spray the lichen until they are thoroughly soaked. 
  2. Wait 15 minutes to allow the outer layer of the growth to soften. 
  3. Spray the lichen until they are thoroughly soaked again. 

The first application will make it easier for the second to reach the growth’s interior.  

What Should You Avoid When Cleaning A Sidewalk? 

There are two things you should avoid when cleaning your sidewalk: 

  1. Power washers 
  2. Bleach 

Power washers may rid the sidewalk’s surface of stains, but they won’t kill the organisms driving growth. Since a power washer can chip away at the top layer of the sidewalk, using that tool may actually make it easier for organic growth to nestle into the concrete and grow. 

Additionally, power washers are likely to result in a muddy mess, which will negate your attempt at cleaning. Misusing them can also damage your home and exterior surfaces. 

There are new instantly clean products on the market, but they come with a pH of 13.5-14.5 which is right up there with drain cleaners. Who wants to put that on expensive surfaces you’re trying to clean but also preserve.  
Bleach run-off can kill the grass on your lawn. Since bleach has a much higher pH level than Wet & Forget Outdoor, it may also strip your sidewalk of its color and damage its surface. As a result, you could be left with an unintentionally splotchy sidewalk that’s more prone to organic growth in the future. 

Where to Find Wet & Forget Outdoor Products 

Keeping your sidewalk clean of organic growth can help extend its life and keep it stain-free. Purchase Wet & Forget today by heading online or to your nearest retailer.