What Is Spot Free Water and Why Do Detailers Use It?
Spot free water is water with the dissolved minerals removed, usually by deionization (DI) or by reverse osmosis followed by deionization (RODI). With no minerals left in it, it evaporates without leaving water spots, so you can rinse a car and let it dry without wiping.
What Causes Water Spots on a Car?
Water spots are minerals left behind when tap water dries. Tap water carries dissolved calcium, magnesium and other minerals. When a drop evaporates, the water leaves but the minerals stay on the surface as a white ring.
Central Florida makes this worse. Much of the area's tap water comes from the Floridan Aquifer, a limestone aquifer that is naturally rich in these minerals, and strong sun can dry a wet panel in minutes. Spots left on hot paint can bond to the surface, and in severe cases etch the clear coat, which then takes polishing to correct.
Spot free water solves the problem at the source: if there are no minerals in the water, there is nothing left behind when it dries.
How Is Spot Free Water Made?
Water purity is measured in TDS, or total dissolved solids, in parts per million. Spot free water for detailing reads at or near zero. There are three common ways to get there:
Deionization (DI)
Water runs through ion exchange resin that captures mineral ions and replaces them with hydrogen and hydroxide ions, which combine into pure water. This is the water we sell at Supreme.
Reverse osmosis (RO)
Pressure pushes water through a very fine membrane that blocks most dissolved solids. RO alone removes most minerals, but trace amounts can remain.
RODI
Reverse osmosis first, then deionization to remove what is left. High volume systems use it because the RO stage makes the DI resin last much longer.
Spot Free Water vs Tap Water vs RODI Water
Here is how the common water types compare for washing a car.
| Water type | Dissolved minerals | Air dry without spots? | Best use |
|---|---|---|---|
| Tap water | High, especially in Central Florida | No | Pre rinse and wash, followed by towel drying |
| RO water | Very low, trace minerals possible | Mostly, light spotting possible | Washing and rinsing |
| DI water | Near zero | Yes | Final rinse |
| RODI water | Near zero | Yes | Final rinse in high volume systems |
| Distilled water | Near zero | Yes | Small jobs; costly at car wash volumes |
Why Use Spot Free Water for Car Washing?
Saves drying time
Rinse and let the car air dry or use a blower. Less wiping means more cars finished per day.
Works in the Florida sun
Fast evaporation is what makes tap water spot. Spot free water can dry in full sun without leaving marks.
Clean glass and trim
No white residue on windows, black trim, chrome or wheels.
Cleaner coating prep
A mineral free rinse leaves a cleaner surface before you apply a sealant or ceramic coating.
Protects coated cars
Ceramic coatings and PPF make water bead, and each tap water bead still dries into a spot. A spot free final rinse prevents it.
A better result for clients
Mobile detailers bring their own spot free water so the finish does not depend on the hard water at a client's house.
How to Use Spot Free Water When You Wash
- Wash with regular water. Use a quality car wash soap and your normal wash process.
- Rinse off the soap. Regular water is fine for this step.
- Final rinse with spot free water. Work top down, panel by panel, until all tap water and soap are replaced. Do not forget mirrors, door jambs and trim gaps.
- Dry. Let it air dry, use a blower, or finish with a plush microfiber drying towel.
Where to Get Spot Free Water in Central Florida
Supreme Detailing Superstore sells deionized spot free water at our Orlando and Maitland stores for $0.35 per gallon, or $0.30 per gallon for Supreme PRO members. It is free with every detailing bay rental.
Fill Up Often? Save 15% With Supreme PRO
For $9.99 per month, Supreme PRO gives you 15% off spot free water and detailing chemicals, plus 25% off bay rentals and Detailing Academy classes at every Supreme store.
Join Supreme PROSpot Free Water Questions
What is spot free water?
Spot free water is water with its dissolved minerals removed, usually through deionization or reverse osmosis followed by deionization. With no minerals left in it, it evaporates without leaving water spots on paint, glass or chrome.
Is spot free water the same as distilled water?
No. Distilled water is made by boiling water and condensing the steam, which also removes minerals. Spot free water for detailing is usually made by deionization, which is far more practical for the volumes a detailer or car wash uses.
What is the difference between DI water and RODI water?
DI water is filtered through ion exchange resin that removes dissolved minerals. RODI water goes through a reverse osmosis membrane first and then DI resin. Both produce spot free water. RODI is common in high volume systems because the RO stage makes the resin last longer.
Can I let my car air dry after a spot free rinse?
Yes, that is the main reason to use it. If the final rinse fully replaces the tap water and soap on the surface, the car can air dry without water spots.
Do ceramic coated cars still get water spots?
Yes. Coatings make water bead, but each bead of tap water still leaves minerals behind when it dries. A spot free final rinse keeps those beads from leaving marks.
Why do I still see spots after rinsing with spot free water?
Usually tap water or soap was left in seams, mirrors or trim, or the final rinse missed a panel. Rinse top down until all tap water is replaced, and blow out mirrors and gaps before the car dries.
Is spot free water safe to drink?
The spot free water sold at Supreme Detailing Superstore is for washing and detailing vehicles, not for drinking.
Where can I buy spot free water in Central Florida?
Supreme Detailing Superstore sells deionized spot free water at our Orlando store on S. Orange Avenue and our Maitland store on Candace Drive for $0.35 per gallon, or $0.30 per gallon for Supreme PRO members. It is free with any detailing bay rental.