If you use a pressure washer during your fundraiser you can wash twenty cars with one capful of soap in a two-thirds filled five-gallon water bucket. Of course your soap will be biodegradable. At least twenty-five percent of the cars you wash will not require the use of soap due to previous wax coats that have been applied. These cars combine to lower your wet/rinse cycle to about thirty seconds of spray time or 1.2 gallons of water per car. This is fifty times more efficient. You can wash fifty cars with a pressure washer to the one car washed with a garden hose in the driveway. This constitutes a significant savings in water.
If you spray a car with special equipment (pressure washer) you will get a fine mist spray. The water can be applied evenly and gives the run off a spread effect. Thus the water that reaches the ground evaporates quickly. A car that needs to be soaped will have a wet/rinse cycle of about one minute and will use about two gallons of water. This water never reaches the storm drains.
You can also contract with a local professional mobile car washer or car detailer to help your group. They only use 2.4 gallons of water per car and their pressure washers only put out 2.4 GPM. If they spray a car for twenty seconds to get it wet, then soap off the dirt and then rinse the car for approximately forty seconds this equals sixty seconds or one minute of sprayed water at 2.4 gallons per minute.
Working with a local professional can be very efficient. You can also purchase a pressure washer from a large department store and do it yourself. By the time you’ve washed 150-300 cars at a fundraiser you too will become very efficient with the water. Look for a pressure washer that puts out 1,500 PSI (pounds per square inch). Gasoline driven units are best, but electric units are about one-half the cost. Remember, if you plan on buying an electric unit make sure that you have an outlet near your designated wash area. Expect to pay $300 for a good electric unit and $500 to $800 for a decent gas unit.
You may also be able to borrow a pressure washer from a local painting contractor. They use them a lot to clean the exterior of homes and commercial buildings before painting. See if someone in your group has a parent who is a painter. Maybe they will volunteer to act as a sprayer during your fundraiser since they have experience using this type of equipment.
If you will be using a straight garden hose remember that fundraisers generally use approximately 3,600 gallons of water; 360 minutes @ 10 GPM. So use shut-off nozzles or kink the hose when you’re not spraying. If you use a pressure washer you will cut your wash time in half thus allowing you time to do twice the number of cars and earn more money. You will also have a lot less water to worry about that might be going into the storm drain.
At one fundraiser using a pressure washer, we washed 520 cars with 950 gallons of water in six hours. Approximately 150 cars with 3,600 gallons of water is generally the maximum amount of cars washed at this type of function using conventional methods. At this particular fundraiser we washed three and one-half times as many cars with one-third the water. We saved the City of Thousand Oaks, California 2,650 gallons of water that day and made the kids a substantial amount of money.
Fixed site car washes also conserve their water. That is why they are allowed to stay in business during a water shortage. They use seventy gallons of water per car during their complete car wash cycle. Four gallons of water is used during the pre-wash cycle. Sixty-six gallons of water is used during the soap/rinse cycle. Nearly two-thirds of the soap/rinse cycle water can be recycled. These approximately forty-four gallons of water are captured in a 10,000 gallon storage tank where they are used over again for car washes for the next three days. This dirty water is mixed with white sudsy soap and used during the car wash soap cycle. The average fixed site car wash uses four gallons (pre-wash) plus twenty-two gallons (sixty-six divided by two-thirds that is recycled) in the soap/rinse cycle bringing the total to twenty-six gallons of water per car. In the car washing industry this constitutes extreme efficiency.