Revised On: March 15 th, 2024 - 9:30 a.m.

Learning Objectives:

• Identify car wash types and their water use
• Evaluate cleaning products for common chemicals to avoid

Types of Car Washes

Car washes have become increasingly popular in urban areas. Today, there are many options customers can choose from based on the machinery, structure, and wash method employed. Categories include automatic or manual, in-bay, tunnel, conveyor, and more. While commercial car washes use less water per car than washing at home, they still waste significant amounts of water daily due to the large volume of serviced vehicles. Many commercial car washes use a reclamation system to cycle the same water on multiple vehicles. Unfortunately, other risks are associated with these establishments aside from the amount of water used. Leaks from piping, cracked flooring, and seepage can enter soil, storm drains and dry wells, contaminating surface and groundwater. 

Common Chemicals 

Car wash establishments typically employ an array of chemicals to cleanse vehicles thoroughly. Among these are presoak, shampoos/detergents, tire & wheel cleaners, triple foam, drying agents, and clear coat/sealants/protectants. Presoak functions by eliminating dirt and grime from the vehicle. It is available in high and low pH variations, which are utilized to counterbalance soaps. Shampoos and detergents are usually applied as a foam soak. They possess a neutral or low pH and high lubricity, which aid in the removal of solids and sealing surface cracks. Tire and wheel cleaners function to remove buildup and come in acidic and alkaline variations. Triple foam is a conditioner and polisher, protecting the vehicle's paint. This is responsible for that shiny finish. Drying agents act as rinse aids, repelling and removing water from the vehicle's surface through beading. Finally, clear coats, sealants, and protectants provide UV and other elemental protection to the car’s exterior. While all these are necessary to please customers and provide them with a clean vehicle, most of these chemicals contain dangerous substances.  

Common chemicals to avoid:

• Teflon and Fluoropolymers are used as luster and surface protectants, such as in car wax and wash products. These products use PFAS, which are toxic and carcinogenic to wildlife and have been linked to birth defects and cancer.
• Phosphates are commonly used as detergents. Their use can lead to eutrophication - a process in which an excessive amount of nutrients in water bodies can cause an overgrowth of algae and other aquatic plants, leading to oxygen depletion in the water and harm to marine life.
• Methanol is a petroleum solvent used in window and glass cleaners and is acutely toxic and can be harmful if ingested or inhaled.
• Kerosene is a synthetic distillate commonly used to cut grease in all-purpose cleaners and degreasers. It can be harmful to human health if inhaled, as fume exposure can cause damage to the lungs, and it can also disturb the fatty tissue surrounding nerves.
• N-propoxy propanol is a chemical that can be found in cleaning products. Exposure to this chemical can irritate the mucous membranes, resulting in itchy eyes, nose, and throat.

These chemicals are a short list of the many dangerous substances found in cleaning products. When purchasing cleaning agents, take note of the ingredients present. If improperly handled or disposed of, the ingredients listed above pose a risk to the employees handling them, the customers, and the environment. Always opt for safer alternatives that are environmentally friendly. We will review some options in the next section.

Full-Service

Full-service auto detailing is a popular but costly cleaning method covering a vehicle's interior and exterior. There are two types of full-service exterior car washes: automatic and manual. Usually, interior cleaning is done manually. Despite using less water per vehicle, automatic full-service washes can wash more vehicles daily than other service styles.

Some businesses offer full-service mobile detailing, where they wash the interior and exterior of the car at the customer’s home or another location. Mobile detailers should never let their wastewater run into the street. Employees should use water catchment systems, like shop vacs, portable wash pits and mats, to retain the wastewater and safely discharge it to the sewer. A sewer is not always readily available due to the nature of mobile work, so it's recommended to use Safer Choice or other eco-friendly products that allow the employee to dispose of wastewater safely on a porous surface. It’s important to note that wastewater containing conventional cleaning chemicals should never be dumped on land, as the water can contaminate the surrounding soil or seep into the water table. Incorporating best management practices (BMPs) guarantees secure operations, as no structural measures are in place to ensure safe wastewater management. By adequately training staff to contain their wastewater, properly maintaining equipment to prevent leaks, and investing in efficient equipment that reduces water use, mobile car washing activities can significantly reduce the risk of harmful substances entering the environment.

Self-Service

Self-serve washes allow customers to wash their vehicles by paying for tools and supplies. This type has equipment and cleaning agents in individual bays for customers.  High-pressure washing, rinsing, waxing, and polishing are commonly provided. Self-serve styles use less water than full-service styles or washing at home. In fact, self-service car washes have a 50%-80% water savings. The Arizona Department of Water Resources Statewide Conservation Program states that self-service washes use about 12 gallons of water per vehicle (GPV) and generate 19.8% water loss due to evaporation on carryout. Self-service styles use the least water per vehicle.¹

A pertinent challenge with self-service washes is the lack of supervision. Customers are known to dispose of oil and debris in the wash troughs. This practice makes water recycling a problematic task. Nevertheless, self-serve car washes can conserve water by utilizing high-pressure nozzles with flow rates of less than three gallons per minute (gpm). Deionization equipment can also be worth considering to provide "spot-free" rinse options rather than water-softening or reverse osmosis systems. Deionization is a process of removing minerals from water by extracting ions from the water supply. Pressure nozzles, deionization equipment, and water recycling can help conserve water use.

For waste management, it is worth considering providing recycling and trash bins to customers to dispose of recyclables and trash. To prevent bin contamination, it would be beneficial to display signage that clearly states the allowable contents of each bin. If there is a common contaminant, more specific signage can be used to reduce repeated contamination.

Regarding water conservation, efficient wash equipment maintenance guarantees optimum performance and prevents excessive water use. Ensure your self-service car wash has positive shut-off valves to avoid waste. Reoccurring leak checks on the spray nozzles and using stainless steel nozzles instead of plastic or brass can extend the equipment’s lifecycle, help reduce water consumption, and lead to cost savings. 

In-Bay

In-bay style, a stationary car wash where equipment moves around the vehicle, is deemed the least efficient among the styles listed in this section. Some in-bay car washes use a reclamation system. The process begins with a pre-soak, followed by a wash cycle, a rinse, an added clear coat, and ends with a final rinse. In-bay washes do not usually offer automatic dry cycles.  While it provides a more consistent wash than the conveyor type, it has relatively high evaporation and carryout rates, reaching 32.8%. Furthermore, it consumes an average of 72.5 gallons per vehicle (GPV), surpassing the usage of other car wash types. Reclamation systems at in-bay lead to much greater cost savings than conveyor-style washes².

For in-bay car washes, there are various ways to incorporate P2 measures. First, replacing nozzles and conducting regular leak checks are essential to prevent excessive water use. Alongside this, alignment checks on nozzles may minimize water waste. Next, only activate the wash arches when the car enters and immediately turn them off when it exits. This approach can effectively reduce water and energy usage. Finally, programming a dry time for water to run off the vehicle into the reclaimed pit before the car leaves can prevent contaminated runoff. By implementing these relatively straightforward measures, water pollution can be prevented.

Conveyor

The conveyor car wash is an efficient system that pulls a car through a tunnel of varying lengths and washing equipment. The process includes a pre-soak,  high-pressure washings with soft cloths and soap application, rinse cycle, wax and polishing, and a final rinse. Most facilities use reverse osmosis (RO) for a spotless finish. Most conveyor systems have reclaimed water tanks where rejected water is cleaned and reused. With relatively low evaporation and carry-out values of 16.7%, this car wash consumes approximately 43.8 gallons of fresh water per vehicle (GPV), which is relatively low compared to in-bay car wash types ¹.

To promote sustainability, consider these P2 opportunities for conveyor styles. Rollover equipment using less than 3.5 gallons per minute can be used for light trucks and small vehicles. Similarly, rollover equipment that uses less than 3.5 gallons per minute can be implemented for buses and large trucks. These measures can save between 50% and 80% of water, making them worth considering for water conservation efforts³.

Regarding water use, using commercial car washes is better than washing your vehicle at home. In fact, washing a car at home can consume as much as 148 gallons of water, which is significantly higher than that used by a commercial car wash. However, car washes can service hundreds of vehicles per day. Due to the volume of customers seen, operators must be proactive with water and chemical management. Checking for leaks, investing in sustainable materials, and safely discharging wastewater to the sewer system are some of the many best management practices that prevent pollution. In the next section, we will discuss general P2 opportunities that apply to all the car wash styles mentioned in this section.

In the next lesson, we will learn about P2 opportunities.

¹ From ADWR’s Water Saving Technologies for Commercial Car Washes, 2009.
² From ADWR’s Conservation Technologies, n.d. 
³ From ADWR’s Water Saving Tips for Washing Your Vehicles, 2009