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APRIL 2002

Quality Water The Essential Ingredient
for a Quality Car Wash

By Charles Borchard

Quality equipment, the right chemistry, and quality water (not to mention some hard work) are the primary ingredients to a successful car wash. The design of car wash equipment and the buildings that house the car washes have risen to meet the expectations of a much more sophisticated consumer who seeks quality, convenience and value - or should I say added value. Value does not necessarily mean the least expensive, it means obtaining the best quality wash for the price. Whether you operate a full-service car wash/exterior tunnel, self-serve car wash or touch-free automatic, the addition of a reverse osmosis/spot-free rinse system will have an immediate positive impact on your clientele. The reverse osmosis system will deliver a final spot-free rinse to the vehicle at the conclusion of the wash process as it exits the wash. The effective use of spot-free water will displace all residual chemical and city or mineral-laden water (including reclaim water) and allow the entire vehicle, including glass, chrome and painted surfaces, to dry perfectly spot-free!

First it's important to know and understand the quality of the water at your site. There are several ways to determine the quality of water. Your local city water utilities will share this information with you. In addition, most car wash distributors have become knowledgeable about the importance of water quality and therefore have the necessary equipment to test water. With the proper testing equipment, you
can even learn to perform these tests yourself. Total dissolved solids (TDS), hardness, and chlorine test results will assist you in determining the quality of your water. The fact is, anyone washing cars in any area where the TDS exceeds 50 parts per million (ppm) should consider the addition of a reverse osmosis system. What is commonly referred to as a hard-water spot is the dissolved solids left behind when the water evaporates. The reverse osmosis system removes 98 percent to 99 percent of these solids, allowing your vehicle to dry "spot-free." The technology of reverse osmosis has improved dramatically through the years and has become an extremely efficient, cost-effective method of eliminating water spotting in vehicle washing.

All segments of professional car washing benefit from a reverse osmosis system. In unattended vehicle washing, the use of a final spot-free rinse will compliment the blower by allowing any residual water remaining on the vehicle to dry spot-free. In a full-serve tunnel, the addition of a spot-free rinse system eliminates your worst enemy - carryout water! No matter how diligent your people are, towel drying can not address the water remaining in crevices of the vehicle, such as the moldings, side-view mirrors, and headlights. As the customer drives away, this (mineral-laden carryout) water is forced out of these areas, dries and causes water spotting. The use of a reverse osmosis system eliminates this concern as the final spot-free rinse becomes the carryout water and therefore, when it evaporates, there is no residual mineral content.

High-pressure touch-free automatic washing systems have become a science and enormously popular. It therefore requires special consideration. Touch-free technology has evolved dramatically over the last few years. The equipment has become faster, very user-friendly, and a better understanding of chemistry and water has provided true quality washing. A reverse osmosis system with its effective use of spot-free water is almost a pre-requisite in this application. Spot-free water rinses away the combination of chemicals and city water or untreated water utilized during the wash process to guarantee the operator and the consumer a perfect wash every time.

The addition of a spot-free rinse system affords a self-serve operator several benefits. By providing the option of a spot-free rinse, the consumer will opt to purchase the additional time necessary in the bay to utilize this feature while generating an additional profit center for the operator as opposed to the time in the bay being abused to towel dry the vehicle. Marketing tools such as bay signs, counter mats, tank toppers and banners educating the consumer about the value of spot-free rinsing have proven to have a very positive effect. Many consumers who have experienced a wash that utilizes a spot-free rinse feature will look for this feature when selecting a car wash.

Most car wash manufacturers have made provisions for spot-free rinsing to be incorporated into their wash process and either offer or recommend this when building or updating a wash facility. A reverse osmosis system is a simple addition to any wash location and will increase customer satisfaction, generate an additional profit center and create customer loyalty. Many car wash manufacturers now include a reverse osmosis system as standard equipment in their car wash packages. Regardless of the brand of car wash equipment you select, there is a spot-free system for you. It is recommended that you consult with your equipment distributor to ensure the selection of the proper spot-free system for your application. If you don't have a distributor, your equipment manufacturer will be able to assist you in the selection of the appropriate spot-free system.

Ask yourself the following questions:

• What is the daily wash count?
• How many hours is the wash open?
• How much space is available for (water) storage?

The table above illustrates the water usage you can expect.

There are many variations of these usage numbers. For example, touchless automatics that deliver the final spot-free-rinse pass via their high-pressure pump will use about double what is shown. For the in-bay cloth rollover that does not use three-color wax, the low-pressure example shown above can be used. Reverse osmosis systems are typically sold based on the amount of water they produce in a 24-hour day, usually at optimum performance with 77º F feed water. If your calculations show that you are close to maxing out a system's capacity, upsize your storage tank or select the next size up system. You may just find yourself with an additional application for this 98 percent pure water! There are increasingly more ways for the spot-free water to be used in car washes. Mixing it with your soap is just one example.

All car washes - soft cloth, either conveyor or rollover; high-pressure touchless automatics; and self-serve bays - use water as the primary means of rinsing the dirt, road grime, salt, and snow off the surface of the vehicle during the wash process. All soaps use water as the delivery medium from the chemical station out to the vehicle to assist in breaking up those contaminants.

Water softeners have been a mainstay in the wash industry and have provided a means to remove the hard mineral deposits that prevent soap from working efficiently. Water softeners have been utilized to overcome the calcium carbonate that is the primary component of water hardness. The hardness is removed via a process called ion exchange. The calcium carbonate ions are attracted and attach themselves to a resin spheroid with dimples such as a golf ball. Residing in these dimples are salt ions, which are displaced when the hardness ions are stripped from the water. The salt, which is a soft ion, takes the place of the hardness. Water softeners require regular service and must maintain a prescribed level of salt to operate and are sometimes particular as far as their regeneration cycles go. In Southern California, municipalities and water departments are severely limiting, and in some cases prohibiting, the use of salt-regenerating water softeners due to concern regarding the increased levels of salt in ground water. It is for these reasons that softeners have become less attractive than they once were. This has helped promote the use of the pure mineral-free and spot-free water generated by a reverse osmosis system for your chemical applications.

It should be noted most reverse osmosis systems require a water softener as a pre-treatment to assist in preventing scaling of membranes due to water hardness. Scale-preventing proprietary technology, which is passive, non-mechanical, and non-electric, does, however, exist.

Water is an increasingly expensive commodity, making reclaim and recycle systems an intelligent choice. Many municipalities now require such systems prior to permitting and these systems could assist in avoiding expensive impact fees. Reclaim systems have made great strides in cleaning and re-using the processed water, and while there are chemicals formulated to work specifically with processed reclaim water, you will improve the cleaning ability of your chemical by utilizing spot-free water generated by your reverse osmosis system.

In touchless automatics, where you rely solely on high-pressure water and quality chemistry, it is very important to use the highest quality water you can. Hard tap water is better than reclaim, softened water is better than hard, spot-free is better yet. Mixing your pre-soak chemicals with spot-free water is gaining popularity with wash manufacturers, chemical suppliers, and large multi-site wash owners. As shown in the table above, most touchless automatics would use 2 to 4 gallons per wash depending on manufacturer and whether they use a single soap pass or a two-stage product. Heating the water and soap mixture is also helpful. However, if you are using spot-free water, please verify with your heater supplier that the heater element is compatible with the purified water. Carbon steel-based heater cores will be dissolved in short order. Copper coils are a little more tolerant, but the pure nature of the spot-free water is very attractive to the solder joints, which can deteriorate or leak in time. Ceramic-lined heaters are currently being tested with over 350,000 gallons of reverse osmosis water having run it's course with no ill effects. The results have been positive and may provide a cost-effective alternative. Currently, stainless steel would still be the best choice.

All reverse osmosis systems work much the same way. Tap water is introduced into a pump, which increases the pressure to between 180 and 250 psi and forces the water through a membrane or membranes. The most common membrane size used in car wash applications is the 4-inch x 40-inch. This membrane requires 5 gallons across the surface of the membrane for every gallon of permeate, or product water, you make. A number of years ago you would just send the 4 gallons of "bad" or concentrate water down the drain. As stated earlier, water is getting to be expensive and in some places you are limited as to how much water you can send to sewer. Most reverse osmosis manufacturers recirculate a portion of that concentrate back into the inlet stream. The standard seems to be that out of the 5 gallons you started with, 1 gallon of permeate is made, 1 gallon goes to the drain, and 3 gallons are recirculated. This is the formula we follow in our small systems, up to 3,000 gpd. In larger systems, you can reject less. Nowadays that is sometimes not enough and we are seeing an increase in "reject capture" systems.

Sometimes, if a car wash site has a reclaim system, the concentrate or reject water is plumbed into the reclaim holding tanks. For every vehicle washed in a system with a reclaim, you will need 6 gallons of make-up water due to carryout and evaporation. Looking again at the table, above, it can be seen that in almost all applications that water would come from the final rinse. With the introduction of the reject water into your reclaim, you will be turning the water in your tanks over and sending the "overflow" to the sewer. This will improve the quality of your reclaim water by diluting the solids and therefore keeping it fresher.

In applications without a sewer hook-up, called "zero-discharge" systems, the concentrate is captured in a tank. As the wash requires "make-up" water, a float in the reclaim tank tells the pump the reclaim is low on water and the pump responds by filling the reclaim tank and keeping the wash running, without wasting water.

There are many possible uses for this "reject" water. In some cases, where there isn't salt present in the reject water, it can be plumbed into the irrigation system and utilized for the landscaping. Wash systems without a reclaim can still capture the reject and, when mixed with tap water, can be used in the wash process. This is a good application where the site may not have enough tap pressure or volume of water.

The uses for spot-free water in a car wash now also include windows. Do you have a nice big window for your customers to view their vehicle as it is being washed? Or do you have a window in your
in-bay automatic through which you want people to view your wash from the street? Maybe you have a car wash that is housed entirely in a structure primarily made of glass. The flying soap, the grime you blasted off that muddy truck, all the junk in the wash bay can accumulate on your windows, and probably will. If you periodically rinse those windows with spot-free water, you will improve the visibility through the windows and reduce or eliminate the laborious scrubbing that would otherwise be required to keep them clean. That's a great use of the spot-free water, a wonderful housekeeping tool, and another way to reduce labor!

Reverse osmosis systems and their effective use of spot-free water have really come of age. As the car wash industry continues to become more competitive and the consumer more sophisticated, the addition of a spot-free rinse system can provide you the competitive edge you need to keep your customers coming back to your site for all their vehicle washing needs!

Charles Borchard is vice president operations for North Highland, CA-based Pur-Clean Spot-Free Rinse Systems ( You can contact Charles via e-mail at

Above: The conveyor tunnel is only one of many car wash applications for a reverse osmosis system.

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