Power Washing

A Stormwater Guide for Power Washers: Proper Washwater Containment, Collection and Disposal

Clean water is important to all of us! It’s up to all of us to make it happen. Over many years, sources of water pollution like industrial wastes from factories have been greatly reduced. Now, more than 60% of water pollution comes from things like cars leaking oil, fertilizers from farms and gardens, and failing septic systems. All these sources can add up to big pollution problems.

Power washing can actually help keep pollution out of our local waterways if done correctly. The problem is that there is more than just water that runs off from power or pressure washing. For instance, the grime that comes off parking lots can contain oil, grease and toxic chemicals. If washwater is not collected properly, all of this pollution will run along with the water into the storm drain. The water that enters a storm drain is not treated or cleaned before it enters our rivers and lakes. 


The Town does not require that you use a specific containment method. However, proper containment should prevent any washwater from entering storm drains or nearby streams. It will also allow you to collect washwater and dispose of it properly. There are two major approaches to washwater containment. 

The first method is to let the washwater flow to a low point and collect it there. Follow these steps to use this method: 

  1. Determine where all the storm drains are located. 
  2. Determine where the high and low spots are on the property to understand where the water will flow. 
  3. Make sure to block or plug any storm drains in the path of your washwater.

The second method is to contain washwater from smaller jobs at the cleaning site. This is done by using collapsible pools, containers or trays to capture washwater.


Washwater can be collected from its containment using a wet vacuum, a sump pump or a vacuum pump. It is important to collect your washwater because any pollutants left on the pavement will eventually be carried into a nearby storm drain or stream by rainwater. Washwater that contains soap, detergent, cleaning products, hazardous waste or large amounts of any other pollutant, cannot be left on paved surfaces.  

  • A sump pump or wet vacuum can be used with a flexible berm to collect washwater. 
  • A generator can power your sump pump or wet vacuum. Be mindful to keep power cords out of the water to avoid safety risks! 
  • Plastic tanks can be used to temporarily store washwater until it can be disposed of properly.

Other Options 

There are many options besides those shown in the previous sections. The Town does not require any specific method or equipment be used so long as you properly contain, collect and dispose of your washwater. Other options include 

(A) Rotary cleaners that supply high pressure water and collect dirty wash water in an attached storage tank, 

(B) Vacuum booms or berms that seal to the ground and suck washwater through a hose to also collect in a storage tank, and

 (C) Ride-on surface cleaning vehicles that collect and recycle washwater.


Once you have contained and collected your washwater, you will need to dispose of it properly. Proper disposal methods include using the sanitary sewer system, using a private treatment company, and more. For any of these methods, you may need to pre-treat your water.

Sanitary Sewer Disposal

If you dispose of your washwater in the sanitary sewer system, you may need to get approval from OWASA before disposing of your washwater in the sanitary sewer system. Contact OWASA Customer Service at 919-537-4343

Disposal to a Planted Area 

In special cases, you may be able to dispose of your washwater in a landscaped area with grass or plants. The planted area must be able to absorb all the water you place in it. You will need to obtain the property owner’s permission before using this disposal method. 

Washwater that contains any of the following may NOT be disposed of in a planted area: 

  • Grease or oil 
  • Food wastes or scraps 
  • Solvents 
  • Hazardous materials 
  • Chlorine 
  • Surfactants/soap 
  • Biological wastes 
  • Petroleum products