Power washing (or pressure washing) vehicles, outdoor equipment and buildings can be very satisfying for appearance and important for maintenance. Maximize overall positive outcomes by following environmentally-responsible procedures. You will often need to collect and properly handle the water used in the process. Contaminants that enter storm drains and bodies of water can harm plants and animals and impair water quality. Even discharging detergent-free hot water can have negative effects.
Have a plan to manage the dirt, oil, grease and other contaminants that you remove from surfaces, and incorporate best practices into standard operating instructions for both mobile and stationary power washing. This is preparation that will help you keep pressure washing jobs on schedule, avoid costly cleanup or remediation bills and prevent fines for violating regulations regarding stormwater pollution prevention.
Here are seven recommendations for your plan:
1. Know where the spent wash water will go
A key step in planning is to understand where the water, dirt and contaminants will go after the washing. The most common places for water to go are:
- Into the soil if the ground is permeable
- Into a storm drain that will carry the untreated water and contaminants to a stream, lake or other body of water
- Into a sanitary sewer system where the water will be treated before being released
- Into a drain that leads to an on-site retention pond, swale or detention basin
Consider your situation and the best choice for your work. In many cases, a municipality will require a permit for water to be released into a storm drain or sanitary sewer system.
2. Consider lower water temperature
Not all cleaning processes require steam cleaning or hot water washing. Pressure cleaning with water at ambient temperatures can often produce the same results at lower cost and with greater safety for the equipment operators. Moreover, many municipalities prohibit discharge of hot water because it disturbs the temperature balance in the receiving waterbody and can harm aquatic life. Permits often specify an acceptable temperature range for discharge.
3. Research cleaners and detergents
There is complexity hidden in cleaning products labeled “biodegradable” and “non-toxic.” They give the perception of safe use, but these descriptors do not necessarily equate to “zero harm.” The term “biodegradable” means only that a given cleaner won’t harm the bacteria in a water treatment facility and that it will break down faster than a traditional cleaner. Like traditional detergents, biodegradable cleaners can still kill fish and other aquatic life. Meanwhile, the term “non-toxic” does not have a standard definition and can be misleading. Many “non-toxic” chemicals can still severely affect water quality. To protect water quality, some municipalities require collection and processing of water containing any type of cleaner or detergent — even those listed as “biodegradable” or “non-toxic.”
4. Sweep before spraying
Remove gross contamination from surfaces before pressure washing. Sweep up dirt and loose gravel. Absorb spilled liquids and put the spent absorbents into bags or containers for proper disposal. This will help speed cleaning time and minimize the cost of removing water contaminants such as lead-based paint, acids, bases, solvents, oil, grease and mercury.
5. Contain wash water and contaminants
Unless you have a permit that lets you discharge the water and contaminants from pressure washing, you will generally need to collect them for treatment. The following are common methods:
6. Consider wash water recycling units
Portable units mounted on fleet vehicles are one way to recycle water. Another method is to collect wash water used at job sites and return it to a central location to process out detergents, oil and other contaminants.
7. Protect drains
If you have a permit to discharge wash water, you can use absorbent booms and filtering mats to help collect trace oils and sediment before the flow enters your storm drains.
These are important measures to consider. Incorporating them and other best practices into every cleaning operation will help keep sediment, debris, oil and other contaminants out of storm drains and sanitary sewage systems. That improves water quality and helps ensure that you comply with regulations and permitting terms.