Best water deionizers for a spotless car wash

Best Water Deionizers for a Spotless Car Wash

Imagine you spend hours washing and detailing your car and as it starts to dry, you notice water spots beginning to appear.

You feel like you’ve wasted your time.

This is why using deionized water is essential for washing cars.

Deionized water has no minerals that cause visible water spots, and when using it, you get a spot-free wash. There is no mineral residue, and it eliminates odors. Diluted chemical dries your car faster and cleaner, which will save time.

Using deionized water will prevent swirls and scratches and prepares your vehicle for a clear coat for waxing or sealants.

Inside the car, the deionized water is useful for cleaning electronics and tends to clean upholstery better as it is not likely to leave water stains or marks.

If all of that isn’t a plus, using deionized water will save water, energy, money, and the environment.

7 Best Water Deionizers and Their Reviews

After reviewing several models, we have come up with the best water deionizers on the market. A water deionizer system should be used to rinse your vehicle after washing.

In order to make this list, the water deionizer had to be high quality, highly rated, and function for personal use. We also looked for water deionizers that were affordable and left cars with a spotless rinse and had a high water filter/resin life expectancy.

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Last update on 2024-06-12 at 21:00 / Affiliate links / Images from Amazon Product Advertising API

The On the Go dual bed deionizer has earned our top pick. We have found a favorite among our list, and we know you will too!

1. On the Go Spotless Portable Dual Bed Deionizer – Top Pick

Last update on 2024-06-12 at 21:00 / Affiliate links / Images from Amazon Product Advertising API

Similar to the On The Go Mixed Bed Deionizer (reviewed below), this unit is lightweight and great for travel. There are two tanks, so the resin is mixed as you use it. The two tanks will fit in an area of 8” x 20”.

This unit will produce 630 gallons of deionized water at 200 ppm before you need to recharge it.

It comes with a four-foot hose, polypropylene cam lever, a cap, and a travel plug. Also included is a digital TDS meter.

The shipping is reimbursed if the unit is damaged or defective.

Keep in mind that deionizers are designed to rinse cars, not wash them. It will be an expensive carwash if you use it to wash your entire vehicle instead of just a final rinse.

Our Thoughts

The customer reviews are outstanding. While it’s on the pricier side compared to others on this list, we’re confident that this is one of the best water deionizers you can buy.

According to On the Go, this unit will process two and a half more water and will decrease operating costs by 50% compared to a mixed bed system. We found this to be mostly correct, but it comes down to how hard the water is you are pumping through your system.

The only complaint we have for this water deionizer is that the connector between the two tanks is very short. We would like it to have a carrying cart of some sort to move quickly outdoors while rinsing, but it is only a desire and doesn’t deter from this unit’s effectiveness.


  • High life-expectancy before recharge
  • Great for rinsing larger vehicles
  • Great customer service


  • Short connection hose
  • Needs a way to maneuver easier

2. On the Go Spotless Portable Mixed Bed Deionizer

Last update on 2024-06-12 at 21:00 / Affiliate links / Images from Amazon Product Advertising API

The most lightweight water deionizer on this list, the On the Go Spotless Mixed Bed Deionizer weighs only 18 lbs. It measures 22” height by 6.75” diameter. It has an easy-to-carry handle, and the head swivels 360 degrees for a connection from any direction for the inlet hose.

The life expectancy of this filter is 280 gallons of DI water at 200 PPM. This means it will last for 45 vehicle rinses or 7 Class A RV rinses.

This water deionizer comes with a four-foot hose, cap and plug for travel, and an easy-to-read TDS meter. The TDS meter is handheld and digital for error-free reading.

You simply recharge the deionizer with resin to get more life from it. You can purchase resin pellets from On the Go to replenish your unit.

Our Thoughts

We like this deionizer because it is perfect for your driveway or travels. If you are looking for a water deionizer to rinse your RV, this one will stow away perfectly. It is genuinely “On the Go.”

The recharge kit is easy to use and saves time and money.

Many water deionizers require you to drain the water between uses; this mixed bed water deionizer does not require it unless there are freezing temperatures.

This unit will make rinsing your vehicle easier and quicker. There is no need to dry to prevent spots.

To make this unit even better, On the Go backs its product and has excellent customer service.


  • Great customer service
  • Easy recharge
  • Truly spot-less rinse
  • The size makes it great for traveling.


  • Leaky connections possible

3. No Spots Pro Deionized Water Generator

Last update on 2024-06-12 at 21:00 / Affiliate links / Images from Amazon Product Advertising API

No Spots Pro is a portable water deionizer that includes everything you need out-of-the-box. This system produces completely deionized water, so it won’t leave any hard water spots even on black cars.

The No Spots Pro deionizer includes an electronic TDS meter that measures the TDS level of input water.

Here’s a chart that shows the estimated yield based on the input water’s TDS level:

No Spots PRO Input TDS Level = Yield (# Gal)
50 ppm = 800 gallons – Mildly Hard Water
100 ppm = 400 gallons – Hard Water
200 ppm = 200 gallons – Very Hard Water
400 ppm = 100 gallons – What, are you pouring concrete?

This deionizer is equipped with a bypass valve, so you can use regular tap water without needing to alter the setup or your hoses.

No Spots Pro is sourced and made in the United States and is considered to be very high-quality.

Our Thoughts

No Spots Pro receives great feedback from customers. You can find several video reviews on YouTube that show No Spots Pro in action.

No Spots Pro typically reduces TDS to less than 20, and even less than 10 with fresh resin. This means you won’t see any water spots after rinsing your car with deionized water from this unit.


  • Made specifically for vehicles, but works for other things like window washing as well
  • Comes with a TDS meter
  • No more drying with towels or worrying about water spots


  • On the pricey side

4. APEC Water System CWS-300

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The CWS-300 is a versatile machine suited for personal use. The 20-inch canister captures dissolved solids. As it captures these solids, it releases hydrogen and oxygen into the water.

There is no scale buildup and it has a maximum pressure of 90 psi. It weighs 51 pounds and has a flow rate of 15 GPM.

Designed, engineered, and assembled in the United States, this machine has long-lasting filters. It has dual specialty features to remove all mineral ions.

It comes with a moveable stand with wheels and a handle.

When you purchase an APEC water system, they donate to give people worldwide clean drinking water.

Our Thoughts

Our favorite feature on this system is the moveable stand. It makes moving the 51 pounds around extremely easy.

Using this system will make different surfaces shine. Paint, chrome, and glass all shine after a spot-free rinse. There is no hand drying needed, and it really does save time.

It is a large investment initially but will save you money, so you don’t have to purchase DI water. It is easy to maintain and operate. Overall, this water deionizer is heavy-duty, trouble-free, and clog-free.


  • Movable stand
  • Easy to use
  • Great for washing house windows


  • Filters don’t have a long life expectancy.

5. CR Spotless DI-120 Simplest RV & Car Wash System

Last update on 2024-06-12 at 21:00 / Affiliate links / Images from Amazon Product Advertising API

CR Spotless is the first company to make water deionizers for personal use for washing vehicles. Their units are the first to be affordable, compact, and portable, unlike CR Spotless’s competitors.

The DI-120 will wash and leave your cars, boats, RVs, and golf carts spotless.

The DI-120 comes with a 20-inch cartridge that will produce about 200 gallons of deionized water. Two hundred gallons is the average. Depending on water in your area, it could deionize 75-1000 gallons depending on the ions and minerals in your water.

The cartridge has a stand that makes it easy to lift and carry. There is a meter to measure the life of the cartridge. This is battery powered.

Besides the cartridge, you also get a stainless steel input line, filter wrench, spray nozzle, and the purity indicator.

Our Thoughts

The DI-120 performs as to be expected. It is quite bulky and heavy to move around, but it does leave your vehicle spotless after washing your car.

The meter can be quite confusing, so be sure to read directions.

There are also limits on how much water flow can be pumped through the filter, so be aware of that. You might consider purchasing a flow restrictor to add to this water deionizer.

We do love that this unit comes fully assembled and ready to go out of the box. However, it is a game-changer and will save a lot of time and energy while washing your car. It leaves the car spotless without having to dry it.


  • Don’t have to dry the car
  • Comes preassembled
  • Works as expected


  • Heavy and bulky

6. AquaticLife Deionized Spot-Free Car Rinse Unit

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AquaticLife has created an all-in-one kit for a spotless car rinse.

This kit needs some assembly. It comes with a mounting bracket, plumber’s tape, two cartridges, a wrench, adapters, and a flow regulator.

Suitable for any vehicle, this dual deionizer removes TDS (total dissolved solids) in water. Water passes through a resin to purify it. The resin then turns tan so you can see when you need to replace the cartridge.

The life expectancy of the cartridge is 1800 TDS. To use this water deionizer, connect it to a water supply, and use a fine mist water nozzle for a spot-free rinse.

Our Thoughts

The AquaticLife Deionized Spot-Free Car Rinse Unit is the cheapest water deionizer on our list, but that doesn’t mean it’s no good. We like this water deionizer for several reasons.

First, we like that it comes with a flow regulator to help protect the canisters’ lives. It works well with all kinds of water, including tap water, well water, and softened water.

The color-changing resin is also a great addition to this unit, so we can easily see when more needs to be added. Instead of changing cartridges, you can buy the resin in bulk and just change the resin.

This unit is durable and built to last.


  • Color-changing resin
  • Dual cartridges
  • Affordable


  • Assembly required
  • Slow flow rate

7. Unger Rinse ‘n’ Go Spotless Car Washing System

Last update on 2024-06-12 at 21:00 / Affiliate links / Images from Amazon Product Advertising API

The Unger Rinse ‘n’ Go spotless car wash system is one of the most affordable deionizers on the market. Unger is based in Connecticut in the United States and manufactures a number of cleaning supplies including the “Rinse ‘n’ Go” unit.

This unit removes all spot-causing contaminants in your water, which results in pure water that doesn’t leave any spots even on dark vehicles or surfaces. You can simply rinse, and then let your car air dry.

The Unger Rinse ‘n’ Go unit is lightweight and more compact than most other deionizers, so you can easily transport it.

The system comes with a TDS meter, an eight-foot hose, a nozzle, and two resin filters.

Our Thoughts

This deionizer is cheap compared to most others on this list, but it still produces good results for most people. However, we did some research and found several complaints that the Rinse ‘n’ Go system only works the first one or two times and then starts leaving spots.

While we do recommend this system, be aware that it may not produce the most consistent results and may need the resin filters replaced fairly often. Unger claims that it supports up to 11 car washes.

For best results, make sure you read the instructions. If spots do appear, it could be due to user error.


  • Compact and lightweight
  • Relatively inexpensive
  • No need to hand dry


  • May not produce the most consistent results

Buyer’s Guide for Water Deionizers: What You Need to Know

Purchasing a water deionizer is an investment. Many units cost $200-$400, and we don’t want you to make a rash decision and then have buyer’s remorse. Before you purchase a unit, there are several factors to consider and questions to ask yourself.

Here are a few basic questions about deionized water, and then we will look at specifics for water deionizers for car washing.

What is Deionized Water?

Deionized water is a real water blank; it becomes whatever the added product is in a diluted form. It is also called demineralized water. Most of the ions have been removed, making it very pure and very clean. Some of the common mineral ions removed are sodium, iron, copper, and more. It is clean, tastes good, and is safe.

This safety is one of the reasons why it is excellent to use to wash your car. It won’t leave a nasty residue or unwanted minerals on your car that could eat your paint and eventually cause rust. There are no chemicals or toxins in deionized water.

The Difference Between Distilled and Deionized

Distilled water and deionized water are often confused. These two types of water are very similar and can be used interchangeably. However, deionized water is purer and goes through an intensive water purification process. It is often cheaper than distilled water.

Distilled water is still pure and uncontaminated. Distillation is the oldest form of purifying water and is far simpler than deionization. Distilled water is more convenient, and distillation removes more impurities than it does eliminate ions. Some people buy distilled water to rinse their cars after washing to prevent spots.

Advantages of Using Deionized Water

Besides the many advantages of using deionized water for washing your car, deionized water will also help avoid the build-up of salts.

It is useful to cool and lubricate machines. Often, it is used in manufacturing process foods, makeup, and medicine.

Finally, you can use it to detox your body; however, you should seek medical advice before trying.

It is also used in many laboratories and to help create new medicines.

What is TDS?

The whole idea behind deionizing water is to remove TDS. TDS is total dissolved solids. Many mineral ions in our water or dissolved solids leave spots or marks on vehicles after washing.

They can also cause scratches, scuffs, or swirls when drying.

Removing TDS from the water will leave your car shinier and cleaner. To deduct TDS, you run the water through a water deionizer. The water deionizer will have a resin that removes the TDS.

The amount of TDS removed depends on how much is in the water, to begin with, and varies by location and water types.

Filter/Cartridge Life Expectancy

As you read through the product reviews, you will notice that each filter/cartridge has a different life expectancy. The life expectancy is an estimate and average.

If you read other product reviews, customers are not satisfied because the resin didn’t last as long as quoted. This is because the amount of TDS in the water will affect the resin and filter’s life. As we mentioned earlier, the initial TDS varies with water type and location. Soft water will be purer after running through the water deionizer than hard water.

Adding a water softener or RO before a deionizer will give you more pure water, which will provide you with a spotless rinse.

Two Types of Water Deionizers

There are two types of water deionizers. You have mixed-bed resin filters and multiple-bed deionizers.

The mixed-bed resin filters are the most popular and often cheaper. They have two resins in one canister, and the water passes through them simultaneously. The resin is a bead-like substance that deionizes water. These resins will remove non-water ions (TDS) and replace them with water ions.

Multiple-bed deionizers do the same thing, but the resin is held in different canisters.

The resin in both types of water deionizers will need to be replaced when they lose the ability to filter water. This can be noticed when you no longer have a spot-free rinse or when your meter says a high level of TDS. Another way to know is by using a color-changing resin. The color-changing resin is an excellent visual indicator and the best way to know. You can order a new resin ahead of time, depending on the color in your canister.

Flow Rate

Throughout this article, we mentioned the flow rate. Flow rate is the flow of the water out of the deionizer and hose. The deionizer needs to flow at a specific rate to ensure the deionizer is being efficient.

If the water flows too quickly, the water will not be deionized, which means there will be spots left on the vehicle. These spots mean there are minerals in the water that could harm the car’s paint, glass, and chrome.

A flow rate that is too fast may also cause damage to the water deionizer. If you are unsure of the status at which your water is flowing, you can purchase a flow regulator that will help extend the life of your water deionizer.


Deionized water is a pure form of water that has no mineral ions in it. A deionized water system should only be used to rinse a vehicle and should not be used to wash the car.

A water deionizer removes TDS to give your vehicle a spotless rinse and leaves glass, chrome, and paint shiny – no more towel drying.

We hope you found the best water deionizer on this list that will help you help you save time, money, and energy and leave your vehicle looking shiny and new.


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