One Chemical Everyone Uses H2...Oh how important - Professional Carwashing & Detailing

One Chemical Everyone Uses H2…Oh how important

Although we often hear that "every car wash is different", you can be sure they all have one key thing in common: water.


Water and the Car Wash

Although we often hear that “every car wash is different”, you can be sure they all have one key thing in common: water. Water is considered to be the universal solvent. It is the most consumed resource in a wash. It can have a great impact on quality of the wash. However, not all water is the same.

Different locations across the country obtain their water from a variety of sources, and different sources can provide significantly different qualities of water. Understanding your water’s quality and the impact it can have on your car wash can help you optimize the performance of your system and the products you are using.

Where our water comes from

Most of us use water that at some point in time, came down to the earth as rain or snow which is (or should be) relatively pure. As the precipitation lands on different types of soils and land use areas, it dissolves a variety of materials which alter its quality. The water eventually finds its way to the lakes, streams, or groundwater reservoirs from which we draw our water supplies.

Every car wash operator should be aware of the source(s) of their water supply, and be familiar with the quality of the water they use. Those who receive their water from large lakes or reservoirs can usually count on fairly consistent water quality. However, if you receive your water from a municipality with numerous wells drawing from different areas, you may regularly see significant changes in water quality. Even those, whose water source is a single municipal or private well, may see seasonal or periodic variations in water quality.

Effects of Water Quality – Water Hardness

“Water Hardness” is the most common and significant component of water quality that effects car wash operations. The term “Hard Water” originally came from the observation that water which contains a lot of dissolved Calcium and/or Magnesium effects laundry detergents and makes it “hard” to get clothes clean.

While these “hardness minerals” are soluble in water, they prefer to combine with other materials, such as soaps and some detergent ingredients, causing them to precipitate out of solution. This results in water hardness stealing the cleaning power that you paid for, requiring you to boost the amount of detergent you use, and increasing your detergent costs.

Water hardness can be removed from the water with a “water softener”. This device removes the Calcium and Magnesium and replaces them with a much more soluble mineral, Sodium. If your water contains over three grains/gallon of hardness, a water softening system will usually pay for itself by enabling you to reduce your detergent usage. If you have a frictionless car wash, it is best to mix your detergents with water that has zero grains/gallon of hardness to obtain peak performance.

Although there are other minerals besides Calcium and Magnesium which can contribute to water hardness, including: Iron, Manganese, and a few other trace minerals, they are generally of little significance and are more likely to cause staining problems than to effect your detergent consumption.

Effects of Water Quality – pH, Alkalinity, & Acidity

Some other chemical factors of water quality that can be of significance to car wash operators are the pH and the Alkalinity or Acidity of the water. If your source water is low in pH, the Acidity of the water can neutralize some of the cleaning power of alkaline detergents. In such cases, the operator may have to use detergents at stronger dilutions to achieve the same performance as operators with neutral or more alkaline water sources.

On the other hand, operators that commonly use low pH detergents and have highly alkaline water may have to use these products a little stronger than operators with less alkaline water.

Such extreme conditions are uncommon, however there is little that the operator can do to compensate for them other than increase the strength of the detergents.

Effects of Water Quality – Total Dissolved Solids

The sum of all the dissolved solid materials in the water (those which cannot be filtered out) is called the “T.D.S.” or “Total Dissolved Solids”. An extremely high T.D.S. can affect car washing regardless of the type of dissolved materials.

The effect of a high T.D.S. on the cleaning process is less commonly understood by operators, and somewhat different than that of water hardness. Where hardness actually removes detergent ingredients, T.D.S. is more of an interference to the detergents. Consider walking across an empty room vs. one filled with people. In either case, you can cross the room, but it will take you longer if there are a lot of people (interference) in the room to slow you down.

In that T.D.S. causes interference to cleaning and is not a complete deterrent, it is difficult to say at what level it is really a problem. In frictionless systems, where detergent performance is critical, it has been observed that using water with zero T.D.S. provides the best detergent performance, yet many washes operate effectively with T.D.S. levels over 500 mg/l.

The problem most commonly associated with T.D.S. has to do with the very last water that goes on the car. Any solids that are in that last water to stay on the car will still be there when the water evaporates. These remaining solids will leave a spot on the vehicle’s surface, and the higher the T.D.S. the worse the spotting. The best way to avoid spotting problems is to use very pure, or “Spot Free” water as the last water to be put on the car.

“Spot Free” water can be produced in one of three ways, Distillation, Deionization, and through Reverse Osmosis. Distillation is not practical for car washes because it is slow and expensive. Operators in need of spot-free should consider the following two methods and work with their suppliers to decide which is best for their circumstances.

Deionization is efficient and cost effective, but it requires the handling of two very dangerous chemicals to regenerate the exchange media. When “Spot Free” systems were first tried at car washes deionization units were used but the chemical handling problems handling problems made them quickly fall out of favor.

Reverse Osmosis (R.O.) is also economical and does not require handling hazardous materials, but it is slower than deionization, which necessitates an additional holding tank to store the processed water. Virtually all “Spot Free” systems in car washes today use R.O. water.

Effects of Water Quality – Temperature

While the temperature of your source water is also a quality factor, it is not often thought of. The colder the source water, the more it will cost to heat it up to the desired temperature. Other than solar pre-heating there is little that you can do to the water to save on your fuel bills. However, you can control your water heating costs during warmer weather by reducing the presoak temperatures, and by using cold or only slightly tempered water for rinsing.

Finally, cold water is generally the best option for sealants, and drying agents throughout the year. These products are seldom helped by using warm water, and frequently perform best in cold water. One exception would be for scented products in which hot water helps disperse the scent much faster. Consult with your supplier for their recommendations.


Like any other aspect of your business, information and understanding are the keys to optimal performance. If you obtain water from a municipal source, they can usually supply you with a complete water analysis report. If you have a private well, there are many private and public laboratories that can run a few standard tests for you to help evaluate your water quality situation.

Finally, work with your equipment and solution suppliers to help you better understand your water quality and achieve maximum performance from your wash and the products that you are using.

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