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TESTED & CERTIFIED

NSF 58 System Certification

The gold standard in water filter certification. 🏅
Cloud RO aced the test. 🧑🏽‍🎓
NSF performance results
How does Cloud compare?
  • ✨ Cloud RO ✨

    98% TDS Reduction Rate
    Low 1:1 Waste Ratio
    Alkaline 7.5-9.5pH

    See Results
  • Traditional RO

    96% TDS Reduction Rate
    High 1:4 Waste Ratio
    Acidic 6-7pH

    See Results
  • Tankless RO

    80% TDS Reduction Rate
    Low 1:1 Waste Ratio
    Acidic 6-7pH

    See Results

NSF Questions Answered

This stuff is a bit confusing, and we learned a lot going through the process.
Here’s what we found out.

What is NSF Certification and why does it even matter?
Water filtration is an unregulated industry. There are many unsubstantiated claims made by water filter manufacturers about system performance and toxin removal rates. The certification process holds water filtration companies accountable. In addition, the certification process looks to create standards and benchmarks so that when consumers are comparing systems they are comparing apples to apples. If you see that a system is certified you know that the claims being made are backed by lab testing and science.
NSF International (aka NSF, aka NSF/ANSI) is the primary certifying body for water filtration. They set the gold standard. Other independent certifying agencies typically use or cite NSF standards within their certification. For example, WQA (Water Quality Association) also offers a certification that is well know and reputable. The WQA certification however uses NSF testing procedures within their certification. Simply put, NSF is the most legitimate, and it is the most stringent of all certifying bodies in the US.

There is a long list of NSF certifications that cover water filtration. Typically the certifications are aligned to a specific technology, for example, NSF 58, which Cloud recently received is specifically targeted towards reverse osmosis systems. There are four main certifications when talking about Point of Use water filtration, meaning a system that filters water at the point you are drinking it. Those certifications include NSF 42, 53, 58 and 401.

To quickly summarize those four:

NSF 42: Focuses on the water's aesthetic effect, how it tastes and smells. Chlorine is the primary driver behind any taste or odor issues, and therefore this certification is specifically targeted towards how well a system can remove chlorine.

NSF 53: This certification is more in depth than the 42 cert. It takes a step further and covers off on all contaminants that the EPA cites as being potentially harmful. In order to pass this standard the filter needs to reduce contaminants to a level deemed “legal” by the EPA

NSF 58: This is the certification obtained by Cloud. This cert specifically focuses on reverse osmosis systems. Reverse osmosis systems typically contain several stages of filtration with an RO membrane being one of them. Unlike the above-referenced certifications, NSF 58 looks at the reduction rate of Total Dissolved Solids (TDS). TDS represents the smallest particles that could be hiding in your water. We will explain more about NSF 58 certification below.

NSF 401: This certification specifically targets contaminants that are not regulated by the EPA. Chemicals and pharmaceuticals that are new or emerging and don’t yet have any regulations fall in this category. It can be a bit confusing because compounds like PFAS actually have moved over to NSF 53 because regulations are now being enforced. This certification is less overarching than the others and is typically added on to NSF 42/53/58 for specific use case

So, why did we choose NSF 58? Well, the answer is twofold, 1) because Cloud RO is a reverse osmosis system and 58 is specifically for RO systems, and 2) because NSF 58 is the best :)

When we say it is the best we are only partially kidding. Reverse osmosis is an extremely powerful technology that removes everything from your water including dissolved particles like salts, minerals, heavy metals, and PFAS. The NSF 58 certification is far more stringent than NSF 42 and 53. Putting a reverse osmosis system up to the 42 or 53 standards would be laughable, as it would blow the requirements out of the water. NSF has made an attempt to be more clear about this in their product literature, stating clearly that NSF 42 and 53 are designed for carbon based systems. The exact wording from NSF is as follows:

“Both standards 42 and 53 cover adsorption/filtration which is a process that occurs when liquid, gas or dissolved/suspended matter adheres to the surface of, or in the pores of, an adsorbent media. Carbon filters are an example of this type of product.”

To state it clearly, NSF 58 is a different certification specifically for RO systems. It has more stringent standards than 42 or 53, and we wanted to start with the most difficult certification out there.

To piggyback off the previous question, we opted to get NSF 58 first because NSF 58 is inclusive of the 42, 53 and 401 standards, and 58 goes a step further by incorporating the reduction of total dissolved solids. NSF 58 is the most stringent point-of-use drinking water filtration certification out there, so we started with that. With that said, there is of course peace of mind knowing that a system has ALL applicable certifications. We plan to layer on all other relevant NSF certifications in due time. The certification process is extremely cost-prohibitive for a small company like Cloud, but we will get there. In addition, we have performed third-party testing to confirm the system does in fact meet the requirements set by the other standards. That supplemental testing was done by SGS laboratories and can be in our data sheet.
Hard no. In our perspective, this is one of the most misleading pieces of information a company can provide. If you see a product is tested to NSF standards that simply means the company has done some lab testing and is comparing their results to the Pass/Fail criteria set by the NSF. We are guilty of using this terminology as well, and now that we have gone through the full NSF process we can assure you it is not the same. NSF has many safeguards in place to make sure the testing actually mimics typical daily use over a prolonged period of time. Many filter manufacturers out there will get a lab test performed with the first pass of water through the system and then make claims about toxin removal rates. Well unfortunately the actual performance in your house will vary over time. This is especially true for carbon and resin based filters that begin to lose effectiveness very quickly. NSF does a great job controlling for this, other labs simply do not. In addition, the NSF 58 certification includes a full system test that not only looks at toxin removal rates, it also looks at the durability of the system, the components being used, the factory making the system, and even extraction testing to confirm nothing is being leached into the water. There is a lot that goes into the NSF testing, if you have insomnia you could read through one of their Certification Policy documents, or you can just take our word for it. Simply stating that a system meets NSF “standards” is not the same as obtaining the certification.
Okay, NSF 58 certification seems legit, how did Cloud perform?
Reverse osmosis is one of the only technologies available that can actually remove dissolved solids (TDS) from your water. Dissolved solids are the smallest particles that may be hiding in your tap water, they are primarily made up of salts and hard minerals, but heavy metals and chemicals can also be mixed in. TDS rejection rate means the percentage of dissolved solids that are removed during the filtration process. When comparing RO systems it is important to look at TDS because it offers us the best available proxy for filter performance. The higher the rejection rate the more powerful the filtration. We think reverse osmosis is extra cool because TDS rejection is a very straightforward measurement that represents a water’s purity post-filtration. Standard carbon and resin-based filters (think pitcher and fridge filters) don’t have a straightforward measurement like TDS that allows you to compare apples to apples. So, what does this mean in the context of NSF testing? Well, NSF 58 certification uses TDS as its benchmark for RO filtration performance. If a system can remove >75% of the dissolved solids coming into the system then it will pass the performance standard. A carbon filter could never achieve this goal but most RO systems can. Reverse osmosis systems typically remove anywhere from 80-98% of TDS. Tankless RO systems perform notoriously badly on the TDS testing because they try to speed up the reverse osmosis process. A tankless system saves a bit of space sure, but at 80-85% TDS rejection they are significantly less powerful from a filtration standpoint. Tank-based, or traditional systems as we call them, usually show strong performance with TDS rejection rates in the 95-98% range. Cloud RO is unique, we have proprietary technology that allows us to maximize filtration performance. Our TDS rejection rate as reported by NSF is 98%, you will be hard-pressed to find any other system on the market that has a higher rejection rate.

Hopefully, by now you have bought into the fact that reverse osmosis is really, really, good at filtering water. Next let’s look at the biggest knock on reverse osmosis, wasted water. In order to achieve truly pure water you need waste. Think about it, if you are removing nearly 100% of the stuff in your tap water then where is all that stuff supposed to go? In a carbon filter, it just grabs toxins and holds onto them. This is far less effective and performance drops as more toxins saturate the filter. RO on the other hand separates the water into two streams, clean water, and wastewater. Anything that is larger than a water molecule (and essentially everything is larger than a water molecule) gets pushed to one side, the waste side, and anything that is smaller than a water molecule (hydrogen and oxygen) is pushed to the pure water or product water side. The waste stream is grey water filled with toxins, and not suitable for human consumption, so it gets dumped in your drain. The percentage of pure water that makes it to your glass is called the efficiency rating. This metric is another leading benchmark associated with the NSF 58 certification. In its simplest form, a 50% efficiency rating means that 50% of the water introduced to the system makes it out to the other end as pure water, and 50% gets sent to the drain as waste. Traditional systems with a tank usually have a ~15-25% waste ratio. This means only 15-25% of the water introduced to the system is making it to your glass and the other 75-85% is being dumped. Cloud has an industry-leading 54% efficiency rating. More than half of the water introduced to the system comes out the other side as pure drinking water.

You may also see a system quote a Recovery Rate alongside the Efficiency Rate. A recovery rate basically means the same thing, but it calculates the percentage of pure water making it to your glass without any inhibiting factors coming into play. The primary inhibiting factor that drives down the percentage is back pressure from the tank. The pressurized storage tank puts back pressure on the RO membrane making it work less efficiently, which in turn sends more water to the waste side. To simulate a recovery rate you would simply plug an RO system in, disconnect the tank and just let the water flow through the RO membrane freely. In a tank-based system the recovery rate is always going to be higher than the efficiency rate because the efficiency rate tries to simulate “real life working conditions”. To give you an example Cloud’s recovery rate as cited by NSF is 66%. This is considerably ‘better’ than the 54% efficiency rating, but it is unrealistic and can only be achieved in a lab setting. Therefore we don’t list our recovery rate anywhere on our data sheet. It is misleading. NSF mandates that any certified systems list their efficiency rating, they give the option to also list the recovery rate, but it always has to be cited alongside the more applicable efficiency rate.

Now, one caveat we must present. Everything listed above relates primarily to tank based or traditional RO systems. Tankless systems work differently so you will notice they actually have a higher efficiency rating than they do recovery rating. This is ridiculously confusing for the consumer and allows tankless companies to cite wildly misleading waste ratios. More on that in the following sections.

Waste ratios take the percentage listed for the efficiency rating and turn that percentage into a ratio of 1. You will see a 1:4 or a 1:3 ratio for most traditional RO systems. The first number is the product or pure water, and the second number is the waste or reject water. So for a system with a 20% efficiency rating, for every 5 gallons introduced to the system 1 gallon comes out as pure water and 4 comes out as waste. Cloud has a ~50% efficiency rating meaning the waste ratio is 1:1.

For the math wiz out there the formula is as follows:
Waste as a ratio of 1 = 1/(Efficiency Rating/(1-Efficiency Rating)).

You will notice we included the word “claim” in the title. The fact is that tankless systems are often misleading, or downright dishonest about their waste claims. They often claim to have 1:3 or 1:4 waste ratios, meaning for every 4 gallons entering the system 1 gets sent to the drain as waste and the remainder hits your glass. While in theory, this may be true, in practice it is not. A tankless system uses a high-powered pump to deliver water on demand, bypassing the need for a storage tank. The result is less waste, this is true. However, the speed of the filtration process puts strain on the RO membrane and causes it to get clogged with hard minerals that want the extra time to get filtered out into the waste stream. To avoid damaging the membrane a tankless system will periodically (like several times a day), flush the membrane, sending several liters of water per day directly down the drain. This happens behind the scenes, and the user typically has no idea. The tankless manufacturers do not calculate this extra flush/waste stream into their ratio. Ya, we know it’s annoying. Now, this is an NSF FAQ so how does the NSF clear this up? Well, unfortunately, we think NSF further confuses the matter. If you read the above question about efficiency rate and recovery rate then you now know the difference between the two. Basically, the efficiency rating is real-life usage, and the recovery rating is flowing the water with zero back pressure from the tank. The recovery rating is therefore higher (better) than the efficiency rating. Well in a tankless system, these numbers are actually reversed. A tankless system has a higher efficiency rating than recovery rating. This is because the efficiency rating doesn't calculate the flush cycles as a percentage of the water dispensed, but the recovery rating does.

We know, this is all very confusing. Click ‘See Results’ above under ‘Tankless System’ to see a marked up version of a tankless datasheet to better understand the slight of hand here. It is very hard to find tankless systems actually certified by the NSF. Most have certified components like replacement filters, but do not hold the full system NSF 58 cert. We included a data sheet above from a reputable brand, so we do trust the source in this rare case.

To summarize, generally speaking tankless systems are more efficient from a wastewater standpoint than traditional counterparts. Our research pegs them at a roughly 1:1 waste ratio, and perhaps slightly better depending on the amount of water being used on a daily basis. The tradeoff is degraded filtration performance.

With all of that said Cloud has a 1:1 waste ratio and 98% TDS reduction. The best of both worlds, no tradeoffs are needed.

We get this question a lot and it is a fair one. We spend a lot of time talking about how much is being removed, but in the era of microplastics and emerging contaminants, you are right to be skeptical about material quality. The NSF 58 certification contains a rigorous extraction test. The system is filled with water and left to sit for a given period of time and then the water is extracted and lab tested. This is done with media (i.e. all filters including the remineralizing filter), and without media. It is done multiple times to ensure accuracy. The results of the extraction test are compared to EPA health guidelines to confirm there is nothing being leached back into the purified drinking water that could negatively impact your health. The extraction test is a big piece of the NSF 58 certification but is not included in all NSF certifications, and is most certainly omitted from any test results you see from third-party certification agencies or labs.
Yes, it does. The full NSF 58 system certificaiton also includes a structural integrity test. THis is again something that sets the NSF certification proccess apart from other testings you may see that claim to ‘meet NSF standards’. The NSF structural integrity test includes static pressure testing up to several hundred PSI, and also includes cycle testing to ensure the system can last several years out in the field. Cloud RO is a new product, we have only been in market since mid-2023, so the durability testing is a huge vote of cofidentence for consumers who may be unsure about investing in something new.
You will notice on the NSF database listing that there is a seperate result for lead content. This can be a bit confusing because while the system removes >99% of lead the the listing states that the “Product also evaluated and determined to possess weighted average lead content of <=0.25%” This is an additional test we added to the NSF 58 testing specifications to comply with certain state plumbing laws in California, Vermont, Maryland, and Louisiana. The laws simply state that any product coming in contact with water needs to either have less than 0.25% lead content, or it needs to contain a label stating that it has lead content. This added certification should give consumers peace of mind that the materials used to construct Cloud are high quality. Many filter companies use faucets that have alarmingly high lead content. The Cloud provided faucet is 100% stainless steel and lead free.
Cloud RO is made in China. We have an excellent relationship with our factory and we are proud of our team there that helps us execute. We are well aware that there are often quality concerns when it comes to products made overseas, but we figure if it is good enough for Apple then it is good enough for Cloud. The majority of microchips, and filtration media are made in China, so you would be hard pressed to find a filter company that actually manufactures 100% of their product in the US. We actually know for a fact that this likely doesn’t exist, even if marketing claims state otherwise. We digress, this is an NSF FAQ so how does NSF come into play here? Well NSF is well aware of quality assurance concerns when it comes to a product category they are going to put their seal of approval on. NSF has offices worldwide, including in China. They have engineers that perform full factory site audits. They review every stage of the manufacturing process to ensure it is up to a high standard. The audit takes place during the initial certification process and annual audits are also required to uphold the certification.
Alright, what’s next in the wonderful world of certification?
Yes, we plan to layer on as many NSF certifications as possible to give consumers 100% confidence in the product. The cost of certification is high so this will take some time. Although they are less rigorous than the already completed NSF 58 certification, we also hope to include NSF 42, 53, and 401. In addition, there are specific contaminants that we can add to our NSF 58 certification and we will likely add those over time as well. In the meantime, we have done supplemental contaminant testing with a reputable third party testing provider, SGS Laboratories. You will see those results included in our data sheet. While the NSF 58 certification keys in on TDS removal, which as discussed is an excellent proxy for filtration power, we also know that consumers want to get a sense of the removal rates for specific contaminants. Those removal rates are posted and labeled in the data sheet. Each of those toxins is tested with the same influent challenge specifications as outlined by NSF to try and give an accurate representation of performance.
Yes there are. This is another way NSF sets itself apart from knock off testing solutions. Anytime materials are changed additional testing is required. NSF also mandates annual audits of the manufacturer facility to ensure quality. Once you have the NSF certification you need to keep up the high bar that has been set.
How do I confirm this is all true and accurate?

Yes, that should be the first step when you see a product certified by NSF. Go to their product search and type in the manufacturers name. When you see the results make sure you identify the specific product you are evaluating and the specific certification (i.e. NSF 42, 53, or 58). There are some common tricks manufacturers will play to make it look like they have a certification when they in fact do not. Sometimes they will get a very lightweight certification like NSF 42, or they will simply get a replacement element certified and not the whole system. This is really misleading and we see it all the time.

To keep things super clear you can access our NSF listing by CLICKING HERE.

Or, if you prefer CLICK HERE and type “Cloud” into the search box

We find this kind of funny, but yes they do provide a PDF certificate. You can see our NSF 58 certificate HERE

The NSF website is a bit hard to navigate:

CLICK HERE for a brief overview of the different NSF certifications offered for water treatment.

CLICK HERE for an overview of the NSF 58 certification.

NSF does not allow distribution of the full standard, but if you contact our customer support we are happy to elaborate on any information provided: support@cloudwaterfilters.com

And if you can't find an answer here, the best way to contact us is via email. We're happy to assist you in any way we can.

support@cloudwaterfilters.com

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