I finally did it. I bought a water filtration system to get spotless car washes. If you don’t know what I’m talking about, I’ll run through it real quick. When we use tap water to wash our cars or really anything else, water spots can develop. This happens because the tap water has minerals in it and if it is left to dry, the water may disappear but the minerals are left behind. I personally cannot stand this. I spend a lot of time taking care of my cars but water spotting is just something that I could not get around. So, I finally just bit the bullet and invested in a water filtration system that would remove the minerals from my tap water and leave me with a spotless car. Well, at least moving forward because the system won’t help with the water spots that are already there.
The system that I went with is the DI Pro 100. If you look at this product up by name, you’ll see that there are a few different companies that sell what seems to look like the same item. The particular system that’s shown in this video is manufactured by RV-Mods and is 100% made in the USA. Other companies buy it from one main manufacturer wholesale, slap a different sticker on, and resell. I can’t speak for any other DI Pro system’s performance, only what I purchased from RV-Mods.
The DI Pro 100 is advertised as being able to filter up to 4,000 gallons of water and costs $585. This was a huge selling point for me. If you’ve been in the market for a deionized spotless car wash system, you’ve no doubt come across the CR Spotless system. This is likely the most popular or, at least, the most widely known system. At $399 it only filters approximately 300 gallons of water. So for $186 more, you can get over 13X the filtering ability. If you can afford the upfront cost, the DI Pro is a no brainer.
So, here is the unit itself. At the top, we have the head unit and bypass valve assembly. Moving down is the 8”x35” tank that holds the 1 cu ft of DI resin.
The system itself is fairly simple. We attach a hose from the tap to the “In” port of the bypass valve and another hose to the “Out” port and that’s where we’ll be getting the filtered water. This process is made a little bit easier as the system comes with quick connectors. As tap water enters the tank, it gets filtered by the resin and deionized water comes out. The great thing about this system is that the bypass valve has controls to allow us to use tap water or filtered water. Some other systems only allow for filtered water once it’s hooked up. With the DI Pro, we’re able to close the valve and use tap water for the main wash. Then, open it up and use filtered water for the rinse. This means that we’re able to really stretch out the resin’s lifespan.
So, is something like this for you? I can't answer that but let me explain to you how I justified the purchase for myself. Getting into a system like this is a bit difficult because there isn’t a lot of information out there on it when it comes to the details. The various manufacturers may say that their system will filter X gallons of water but that does not mean that that’s the amount of filtered water that you’ll get. This was the factor that made me hold off on buying a deionized water system prior to this. How do I know if it’s even going to be worth buying? What if I buy into the system and have to replace the resin after a few washes or after a month? It’s all up in the air.
A major factor in determining how much life you’ll get out of any filtration system is the water that you currently use and what the total dissolved solids (TDS) content that it has. In short, TDS tells you the amount of minerals that are in the water and it is commonly calculated in parts per million (ppm). After some research, I found a web page published by CR Spotless that had some good information. I’ll link the page in the description below but the important thing is that this page gives us the formula to calculate the amount of filtered water that we can expect to get from any system given that we know our water’s TDS prior to filtering and the volume of resin that the system uses. This formula is 235,000 ÷ TDS x Volume of resin = Gallons of “Spot-free Water”. The volume of resin is based around 1 cu ft and is easy to find as many manufacturers list it in the specs. The particular system shown in this video uses 1 whole cubic foot of resin so it’s a given and is nullified in the equation. The only thing that I really need to find was the TDS of my water prior to filtering. To figure this out, I ordered a cheap TDS meter from Amazon and tested my water. After testing my water every day for a week, the meter told me that my water was sitting at 59-91 PPM. This is great news as from my research, this is relatively low. The CR Spotless page actually lists a few different city’s past TDS. San Diego had 400 ppm. Another city in Orange County had 40 ppm. Grand Rapids, Michigan 170 ppm. In any case, TDS ranges quite a bit around the world but luckily for me, I had a pretty good start especially considering that the DI Pro is rated based on incoming water of 110 ppm TDS. To get back to the formula, 235,000 divided by my lowest TDS of 59 would result in roughly 3,983 gallons of filter water. Pretty close to the manufacturer's listed 4000 gallons, which is great! At it’s highest, 235,000 divided by 91, I would get about 2,582 gallons of filtered water. In either case, that’s a whole lot of filtered water.
Considering that I only use this system for a final rinse, I’ll be able to get many washes out of the resin that comes with the original purchase. By my highly overestimated guess of 20 gallons of water used per week and 1040 gallons per year, I’ll be able to get about 2.5 to 4 years’ worth of use. This of course is just a very rough estimate but you get the possibility of the insane value.
If you’re going to try and do these calculations for yourself, there are a few things that I want to point out. First, my testing showed that not all tap water on my property is the same. For whatever reason, the water from the tap that I use to wash cars is purer than anywhere else on the property. So, if you’re going to test your water, test the tap that you’re going to be using the system with to get the most accurate calculations. It should also be noted that the TDS is not going to always be the same. It changes throughout the year based on various conditions so this means that you’ll be getting more or less filtered water depending on the time of the year. Realistically, I got a different TDS measurement on every test within a few seconds. So, it’s more important to understand your range of TDS rather than a specific number. Also, the equation previously shown from CR Spotless is not going to be 100% accurate. Not all manufacturers use this to calculate their filtered water output so the equation should only be used to help, not to be a definitive answer.
But it is still very useful because once you understand the amount of filtered water that you can potentially get from a system, you can then make a much more educated buying decision because remember, this is not something that you buy once and forget about. The resin used to filter the water is a consumable and will have to be replaced periodically. This system uses one cubic foot of resin at a time and that costs $225. To me, $225 for 2.5 to 4 years of use is not all that bad. It’s something that I’m willing to pay for. Now, if you test your water and it’s really high, to the point that you'll potentially only get a few months of use, then I would suggest looking for a different solution because the cost is really going to add up over time.
And that’s about it. I hope that this writeup has been helpful for anyone looking to get into a deionized water filtration system. If you have any questions, leave it down in the comments below and I’ll do my best to help you out. Make sure to also subscribe to my YouTube as I’ll be making update videos in the future as I get more time in with this system.
UPDATE
After less than 100 gallons of use, my water's TDS is sitting at 3 and producing water spots. The manufacturer recommends changing the resin when the TDS is around 50 because water spots shouldn't be a problem until then. However, the problem with TDS is that it doesn't tell us what minerals are present. A TDS of 1 can still produce water spots if the minerals left behind are those that produce water spots. After weeks of contacting the manufacturer of this tank, it doesn't seem like we're going to reach a resolution. I have to say that for the price and to get less than 100 gallons of filtered water, I can no longer recommend this system from RV-Mods.
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