Top 10 Best Reverse Osmosis Filter System : Reviews & Buying Guide
As an Amazon Associate I earn from qualifying purchases.
Buying a Reverse Osmosis Filter System seems like an easy job, but not everytime. There are hundreds of Reverse Osmosis Filter System available on the market from various producers, which is enough to confuse you. They are so similar in terms of performance, quality, longevity, and overall user experience that choosing a final buying decision may be tough. All you need at that point is a comprehensive buying guide to help you find the ideal Reverse Osmosis Filter System for your needs.
In this article, we will go over a few important points to consider about before buying a Reverse Osmosis Filter System. You can call it a proper review guideline for you which will cover pros and cons of your desired product including its sustainability, affordability, functions, and also practical benefits. There will also be a solid comparison of a few related products. As a result, you’ll be able to quickly select the best option for your needs. Let’s take a look at what’s going on inside.
Best Reverse Osmosis Filter System : Top 10 Picks
Last update on 2024-06-26 at 14:42 / Affiliate links / Images from Amazon Product Advertising API
10 Best Reverse Osmosis Filter System Reviews According To Experts
We tried to find the top ten Reverse Osmosis Filter System from thousands of different products in this section. This list will make you feel easy to get your desired Reverse Osmosis Filter System within a few minutes. We emphasized their usefulness, performance, durability, outlook, affordability, and previous user experiences. We are confident that this list of the top 10 Reverse Osmosis Filter System will help you find the one that best fits your needs.
- Supreme quality - designed, engineered, and assembled in USA to guarantee water safety & your health.
- Only technology to remove up to 99% of impurities including arsenic, chlorine, lead, fluoride, heavy metals, and 1000+ impurities. Max Total Dissolved Solids - 2000 ppm. Feed Water Pressure 40-85 psi
- WQA Certified System. Premium long-lasting filters used to treat tap water, well water. Provide unlimited clean, refreshing crisp tasting water superior to bottled water
- America's No.1 rated water filter brand with 20 years of success guaranteeing trouble free, noise-free system for long lasting, dependable, pure drinking water.
- System comes with 100% lead-free designer faucet, plus Certified JG premium grade tubing and parts to provide safe, impurity-free pure water. Pipe Size:1/4 inches
- Certified to NSF/ANSI 58, 6-Stage Alkaline Remineralization Layered Filtration - Exclusively designed to restore the natural alkalinity and mineral balance of water; this reliable and ultra-safe Reverse Osmosis (RO) water filtration system converts your water into clean, pure and healthy drinking water by removing up to 99% of over 1,000 harmful contaminants like PFAS (includes PFOA and PFOS), chlorine, fluoride, lead (removes up to 98%), arsenic, asbestos, calcium, sodium and more.
- GREAT-TASTING MINERAL WATER - A standard 5 stage RO system produces slightly acidic water with a pH of 7. 0 or below because the RO membrane removes not only harmful pollutants but also a few helpful minerals. The iSpring RCC7AK Reverse Osmosis water filter includes an additional 6th stage - an Alkaline Remineralization filter which restores healthy minerals and produces a balanced alkalinity, which gives your water a more natural taste than regular 5 stage RO water filter.
- LOW MAINTENANCE - Transparent 1st stage housing for easy visual inspection. Three extra long life pre-filters to remove large contaminants and protect RO membrane. Ultra fine (RO) filter to remove contaminants down to 0. 0001 microns; fine GAC filter to provide final polishing to the purified water and (AK) filter to finally restore just the right proportion of healthy minerals and a natural alkaline balance. The end result is great-tasting bottled-water quality.
- EASY TO INSTALL & NO LEAKS - The water purifier is designed for DIY installation and all necessary parts for installation are included. Backed by clear installation manual, instructional videos, and access to lifetime technical support. The entire alkaline system fits nicely under a kitchen sink. For leak-free installation, simply push tubing ½” deep into quick-fitting connectors and lock; no threading pipes needed. Note: Please ensure RCC7AK fits your under-sink area before purchasing.
- 100% SATISFIED CUSTOMERS - RCC7AK from America’s favorite brand of under sink water filter is the highly rated reverse osmosis systems. Comes with 1-year limited manufacturer warranty upon registration and lifetime personalized support from GA, USA, combined with premium quality components, this water filter is to deliver endless bottled quality drinking water right in your home for many years to come, eliminating plastic waste.
- 6-STAGE ADVANCED FILTRATION WITH UV LIGHT: The Bluevua RO100ROPOT-UV boasts a superior 6-stage filtration system, featuring a 0.0001μm RO membrane, including UV light and an added remineralization filter. Certified by WQA against NSF/ANSI/CAN 372 for lead-free and tested by SGS, this combination effectively reduces TDS, PFOA, PFOS, Chlorine, Fluoride, Arsenic, Lead, and more, while also enriching water with essential minerals, balancing taste and health benefits.
- Countertop Filtration + Premium-Quality Carafe: No plumbing or installation is required for this RO system. Simply plug this portable piece of tech into any power source and you're ready to fill it up and go! Better yet, the water container is constructed of a high borosilicate glass carafe instead of the traditional plastic, reducing the risk of secondary pollution and making this one of the best countertop water filter systems.
- Power Saving/Water Saving: The water system automatically enters power-saving standby mode when not in use to reduce power consumption. Leftover water from a cycle isn't deemed wastewater so more water is saved to use for various household purposes.
- Filter Life Monitor: The countertop water filters last for a long time between 12-24 months to provide 1-2 years of clean drinking water before needing replacement. Filters are also designed to help save water with an impressive 2:1 Pure to Drain ratio. Monitor display shows the service life of filters and water quality so you can easily keep track of filter replacement and periodically switch out filter tubes.
- Technical Support/Warranty: 1-year warranty can be found in the manual or on Bluevua official website. Simply scan the QR code and fill out the purchase information for 1-year manufacturer warranty registration. In addition, online customer service is also available for help. We stand behind our products and our company. If for any reason you are not completely satisfied with your Bluevua products, we offer a 30-day full refund and a 1-year warranty on all our products.
- 𝐍𝐒𝐅/𝐀𝐍𝐒𝐈 𝟑𝟕𝟐 𝐂𝐞𝐫𝐭𝐢𝐟𝐢𝐞𝐝 & 𝟕-𝐬𝐭𝐚𝐠𝐞 𝐟𝐢𝐥𝐭𝐫𝐚𝐭𝐢𝐨𝐧 & 𝟒𝟎𝟎 𝐆𝐏𝐃 & 𝟏:𝟏 𝐥𝐨𝐰 𝐝𝐫𝐚𝐢𝐧 𝐫𝐚𝐭𝐢𝐨 & 𝐓𝐚𝐧𝐤𝐥𝐞𝐬𝐬 𝐃𝐞𝐬𝐢𝐠𝐧 & 𝐄𝐚𝐬𝐲 𝐢𝐧𝐬𝐭𝐚𝐥𝐥𝐚𝐭𝐢𝐨𝐧; Two filters are included in the package. Search "WD-G2-W" for replacement filters.
- 𝟕 𝐒𝐭𝐚𝐠𝐞 𝐅𝐢𝐥𝐭𝐫𝐚𝐭𝐢𝐨𝐧 & 𝐞𝐟𝐟𝐞𝐜𝐭𝐢𝐯𝐞 𝐟𝐢𝐥𝐭𝐫𝐚𝐭𝐢𝐨𝐧:The G2 system is certified by 𝐍𝐒𝐅/𝐀𝐍𝐒𝐈 𝟑𝟕𝟐 for lead-free materials. The G2 RO System adopts a composite filter result in more effective filtration. Our RO system can reduce TDS, PFAS, PFOA, PFOS, vinyl chloride, monobutyl ether, according to reverse osmosis membrane technical manual.
- 𝟒𝟎𝟎 𝐆𝐏𝐃＆𝟏:𝟏 𝐩𝐮𝐫𝐞 𝐭𝐨 𝐝𝐫𝐚𝐢𝐧 𝐫𝐚𝐭𝐢𝐨: The Waterdrop G2 reverse osmosis system offers a fast water flow rate of up to 400 GPD. Get a cup of filtered water in about 12 seconds, satisfying your needs while saving time. Compared to the ordinary RO system, the Waterdrop RO system always has a stable water flow. This tankless RO has a low drain ratio of 1:1 and saves water waste by 300%.
- 𝐈𝐧𝐧𝐨𝐯𝐚𝐭𝐢𝐯𝐞 𝐭𝐚𝐧𝐤𝐥𝐞𝐬𝐬 𝐝𝐞𝐬𝐢𝐠𝐧: The tankless design ensures the safety of your family’s drinking water. It also saves over 70% more under-sink storage space than does the ordinary RO system. Note that this reverse osmosis system requires under-sink electricity.
- 𝐈𝐧𝐭𝐞𝐠𝐫𝐚𝐭𝐞𝐝 𝐩𝐫𝐨𝐝𝐮𝐜𝐭 𝐝𝐞𝐬𝐢𝐠𝐧: The advanced integrated design of the electrical and water circuits reduces leakage. The airtight housing reduces noise, while the process of installing and replacing the filter is faster and more convenient than with other filters. Due to the filters’ twist-and-pull design, you can replace them in 3 seconds. The installation of the RO System takes less than 30 minutes. NOTE: An electrical outlet and drilling holes is required to operate it.
- TESTED AND CERTIFIED BY SGS: Against NSF/ANSI 58, EPA 537 Standard. Converts your tap water/well water(TDS<500 ppm) into pure and healthy drinking water by removing 99.99% of the 1,000+ contaminants including viruses, bacteria, chemicals (PFAS/PFOA/PFOS, Pharmaceuticals), heavy metals (Lead, Arsenicetc), chlorine, TDS (fluoride, nitrates/nitrites) and etc. Say goodbye to the hidden dangers of tap water
- UV PURIFICATION SYSTEM: Use no chemicals and emits absolutely no by-products, effectively destroying 99.99% of microorganisms, bacteria, germs more thorough sterilization from your water. SimPure UV purification system combined with 3-Stages 0.0001μm RO Filtration System, can take water purification to next level. Taste the refreshing difference
- NO INSTALLATION REQUIRED: Simply plug it in and enjoy purified water instantly. Eliminating installation hassles and complex filter replacements. Unlike traditional under sink water filter systems, Y7P counter top RO water filter free from water source and space constraints. Place it anywhere with a power supply – perfect for homes, apartment, kitchens, offices, camping, RVs, and more
- EFFORTLESS HYDRATION & ELEVATED LIFESTYLE: SimPure Y7P water purifier included a full set of quick-change twist filter cartridges provide 528 gallons of purified water (approximately 6000 bottled water). Embrace a sustainable lifestyle, reduce plastic waste, and save money with SimPure. It's not just purified water; it's an elevated standard of living, making each sip a testament to the purity and sustainability it offers
- HIGH EFFICIENCY IN WATER PURIFYING: Achieving a 4:1 pure to drain ratio, the SimPure Y7P boasts the highest water utilization rate among RO systems available in the market. With the innovative recycling multi filtration technology, it can save up to 1500% more water compared to under sink RO water filtration systems. Additionally, the faster dispense flow rate (418 GPD) ensures you can enjoy a cup of purified water in approximately 15 seconds
- Reverse Osmosis Water Filter: Experience what water should taste like with the Express Water reverse osmosis water filtration system filtering up to 99. 99% of Lead, Chlorine, Fluoride, Nitrates, Calcium, Arsenic, and more
- Alkaline Water Filter: Express Water’s Alkaline Water Filter with Active Mineral Technology adds Calcium, Potassium, Magnesium, and other minerals to your water
- Under Sink Water Filter: Don’t waste money on professional installation. Express Water’s quick and easy-to-understand design means you can install and understand everything about your new water filtration system
- Quality : Rest easy with our 1-year on all Express Water Reverse Osmosis Water Systems. System dimensions: 17x15x5 inches, Tank dimensions: 15x12x12 inches
- Under Sink Water Filter System: No need to mess with refilling or activating your water filter, Express Water’s water filtration systems automatically fill your water tank with high quality drinking water
- 𝐓𝐫𝐮𝐬𝐭𝐞𝐝 𝐜𝐞𝐫𝐭𝐢𝐟𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬: Waterdrop G3 reverse osmosis system is certified against NSF/ANSI 58 for TDS reduction and NSF/ANSI 372 certified for lead-free material. Also it has been tested and certified against NSF 42 to reduce chlorine, bad taste and odor. The tankless reverse osmosis system is also certified by the Federal Communications Commission. Besides, it meets the EU Standards and UKCA Standards for safety.
- 𝟖-𝐬𝐭𝐚𝐠𝐞 𝐟𝐢𝐥𝐭𝐫𝐚𝐭𝐢𝐨𝐧: Tested by official third-party laboratory (SGS), the reverse osmosis system can effectively reduce TDS, chromium, PFAS, radium, fluoride, arsenic salt, iron, calcium, particles, chloride, chlorine and radioactive substances in your tap water. And our RO water filter system can reduce chemicals such as vinyl chloride, ethylhexyl acrylate, isobutylene, ethylene glycol, according to the reverse osmosis membrane technical manual.
- 𝐒𝐦𝐚𝐫𝐭 𝐝𝐢𝐬𝐩𝐥𝐚𝐲 𝐟𝐚𝐮𝐜𝐞𝐭: The tankless reverse osmosis system is built with a smart display faucet. For instance, the TDS monitor tells you the quality of your filtered water, while the filter life tracker shows how soon you need to replace your filter.
- 𝐇𝐢𝐠𝐡 𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐲, 𝟐:𝟏 𝐥𝐨𝐰 𝐝𝐫𝐚𝐢𝐧 𝐫𝐚𝐭𝐢𝐨: As an upgraded reverse osmosis system, this reverse osmosis water system produces 600 gallons of filtered water per day. By its low drain ratio, this system can produce only one cup of waste water for every two cups of pure water produced. Furthermore, with a fast and stable water flow rate, this RO system fills a 8 oz cup of water in 8 seconds, which is ideal for drinking and washing vegetables.
- 𝐓𝐚𝐧𝐤𝐥𝐞𝐬𝐬 𝐝𝐞𝐬𝐢𝐠𝐧: Waterdrop G3 reverse osmosis system has a stylish look. This tankless design saves 70% under sink space. You can change a filter in 3 seconds without moving the system or using any tools. Note: This reverse osmosis system requires under-sink electricity.
- Reverse Osmosis Replacement Water Filters: Experience what water should taste like with the Express Water reverse osmosis water filtration system reducing up to 99.99% impurities.
- Water Purification System: Drink the healthiest water on Earth. All water filters are specially engineered to work together, producing the safest and best tasting water you’ll ever drink.
- Reverse Osmosis Filter Replacement Set: Each Express Water replacement filter is specially designed to work together and compliment each other. Get the cleanest water and the best value in your filtration
- Reverse Osmosis Membrane: The RO Membrane is specially designed with density graded layers of filtration to filter the hardest to remove impurities like dissolved solids, microplastics, fluoride, Heavy Metals, and more.
- Pre-Carbon Filter: Activated Carbon Block and Granular Activated Carbon block water filters protect your system from chlorine damage and reduce volatile organic chemicals.
- [Effectively Remove Contaminants] This iSpring RO system is designed to produce great-tasting water that is clean, pure, and healthy for drinking. It uses a 5-stage filtration process that removes up to 99% of over 1,000 harmful contaminants, including PFAS, chlorine, fluoride, lead (removes up to 98%), arsenic, asbestos, calcium, sodium, and more. The under sink water filter system also reduces the TDS rate by 80% to 90% or better, making it ideal for drinking. Additionally, it removes hard water minerals like calcium, and magnesium that leave white residue or scale.
- [Certified to NSF/ANSI 58] The iSpring reverse osmosis water filter is produced in strict accordance with American quality standards. Certified to NSF/ANSI 58 and has been dedicated to providing unlimited clean, refreshing, and crisp-tasting water superior to bottled water for American families for more than 15 years.
- [Low Maintenance and Leak-free Design] Quality components ensure reliability and low maintenance for many years to come. Clear see-through 1st stage housing makes filter inspection a snap. The system is compact and can fit under most kitchen sinks. It doesn't require any power source and comes with a check valve to prevent the backflow of water into the membrane housing, ensuring safety and avoiding water leakage. With a tank, it can meet the needs of big families or offices. The first filter housing is made of AS material (impact strength), allowing you to see the condition of the filter element without removing the casing and ensuring you always enjoy the best quality of water.
- [High Quality Design and Great Taste] The high-quality iSpring reverse osmosis system under sink helps you experience clean, safe, and good-tasting water every time you turn on the faucet. The system comes with a 100% lead-free designer faucet and certified food-grade tubing, allowing you to enjoy crystal clear ice cubes, fresher tea and coffee, better-tasting foods, and healthier baby formula. The reverse osmosis water system removes contaminants down to 0.0001 microns, and the fine GAC filter provides final polishing to the purified water.
- [100% Satisfied Customers] RCC7 from America’s favorite brand of under sink water filter is the highly rated reverse osmosis system. Comes with 1-year limited manufacturer warranty upon registration and lifetime personalized support from GA, USA, combined with premium quality components, this water filter is to deliver endless bottled quality drinking water right in your home for many years to come, eliminating plastic waste.
- Premium 7 Stages Filtration: RO water filtration system has 7 stages filtration to reduce 1000+ contaminants and improve the taste of water. The RO filter(3 Stages) + PPC(4 Stages) adopts 0.0001-micron reverse osmosis membrane to decrease TDS from 500 ppm to 15 ppm and intercept sand, particles, salt, PFAS, radioactive substances(Radium), fluoride, heavy metals, vinyl chloride, Ethylhexyl acrylate, isobutylene, ethylene glycol
- Smart Faucet with TDS Monitoring and Filter Lifespan Reminding: RO drinking water filter system Offers real-time monitoring of your water's Total Dissolved Solids (TDS), giving you instant insights into the quality of your filtered water. Additionally, the faucet's sensor was enhanced for more precise TDS measurement. Plus, the convenient filter life indicator alerts you when it's time for the RO/PPC filter replacement.
- User Friendly: This ro system under sink measures 15.66” L x 4.48” W x 11.81” H, taking up minimal space under your sink. Additionally, Installation takes only 10 minutes with included 3/8 or 1/2 feed water adapters(Notice: you need to check out the machine with the B0CB13TSXV at NO Cost), pre-install tubing and adapters, and drain saddle. Additionally, our innovative Front-loading filter design allows for quick and easy filter replacement in just 3s, without the hassle of moving objects around the unit.
- Updated 400GPD & 2.5:1 Pure to Drain Ratio: Tankless reverse osmosis system offers faster water flow, actually reaching up to 600 GPD, thanks to our innovative Tubing Design. It can fill a 200ml cup of water in just 7s. Besides, 2.5:1 pure to drain ratio allows you to save up to 250% more on water bills compared to other 1:1 reverse osmosis filter. Offering an economical alternative to bottled water and being environmentally friendly (as no tank means no secondary pollution).
- NSF Certified & Maintenance: Reverse osmosis water filter meets NSF standards, so the TDS removal rate is certified up to 91.9% and the heavy metal reduction rate is certified up to 96.9%. Replace the RO filter every 2 years and the PPC filter annually. [Search RO: B0CJBXKVJX] [Search PPC: B0CJBXZCKX] Check NSF: https://m.media-amazon.com/images/I/A1g4BLtR35L.pdf
Last update on 2024-06-26 at 14:42 / Affiliate links / Images from Amazon Product Advertising API
Things To Consider When Buying Reverse Osmosis Filter System
It is impossible to ascertain everything about anything as a human being. It is impossible to be an expert in every field. In that case, going through a proper buying guide can save us from being fool after purchasing a Reverse Osmosis Filter System just because of not knowing properly earlier.
You do not have to be an expert on that specific product in order to purchase it. Just focus on a few key points that we’ll go over later. Taking these simple considerations into account may make your shopping experience more pleasant and straightforward. Let’s get started.
Understand what you require.
The very first thing to discover is your needs or requirements. If you are not properly informed of your demands, there is a big chance that you will purchase the incorrect things at the wrong time and waste a significant amount of money. So, first and foremost, we recommend that you carefully consider your requirements when searching for a Reverse Osmosis Filter System. Simply make a short list of your requirements. This simple task will lead you to simplifying your purchasing process. Then you will be able to know your prioroties which is the most important thing.
Budget vs Pricing
Before you decide to buy anything, one of the most important issue to think about is budget. Your desired product can be asked any amount of price by it’s seller and producer. That depends on different expences like raw material purchasing, manufacturing, transportation, operational costs and their brand value playes a huge role there. You need to be prepared to spent the higher amount of money if you demand for the higher quality in your product. Budget is so important for this cause. This is almost a universal truth and your Reverse Osmosis Filter System also fall into it.
There is a popular proverb in our society, “Cut your coat, according to your cloth”. First of all, you can find out those products on the internet which you actually want. Look carefully their features and prices. With your deep observation, make a proper comparison among them and select one that you need. Now make a question inward your mind that you are really financially capable enough to purchase that specific Reverse Osmosis Filter System or not? If the answer is yes, then go for it. You may think about the second best option if your answer is no.
Select the Best Brand
Because of our emotional attachments, we are frequently predisposed toward certain brands. This practice yields positive results at times and negative results at other times. However, there is no way to argue with the concept of relying on well-known brands. Because having enough cash in your pocket makes making decisions half as easy. But one thing remains, if you are not 100% sure that your brand of choice makes the best product that you are seeking for. So you have to be very carefull when you are choosing any product if it is the right product from right brand.
People are divided into two groups. One is fully reliant on a single brand, while the other seems unconcerned. All he requires is the appropriate goods for the price he is paying. May be we are not aware of the category that you belong to.However, there are a few pointers that may be useful to both of you when it comes to selecting the correct brand for the right product.
- Make sure in this case that you are well-versed in the brand.
- What people are saying about this brand.
- What is the average rating for that brand’s specific product?
- Contrast the features with those of competitors.
- Does these features meet your necessities?
Analyze the Features Section.
Whether you buy it online or offline, the first thing you should check is while buying is the features of Reverse Osmosis Filter System. This is the best way to know about a product and get a clear concept. You will be able to understand, that product will match with your requirements or not.
The features section also helps us in swiftly identifying the differences with others. Then, using the features, you can compare it to similar products. If you do so, it will be much easier to reach to the final decision because you will be able to understand about the quality here.
Consider the benefits and drawbacks.
Every item has its own set of advantages and pitfalls. It is our job to thoroughly inspect them before purchasing them. So, stay cool, and find out the drawbacks which you demanded from that Reverse Osmosis Filter System. Maybe some other manufacturer made the perfect one for you. Just don’t be too lazy to compare your options to theirs before making your final decision.
Pros and Cons sections can be found on most websites. Take your time reading that part. For asking more you can contact them via email or phone.
Quality and performance
Color, Style, Performance, Materials, and, most importantly, Durability are all factors that contribute to quality. When you are buying anything, be carefull to check those quality related issues. We think you are actually paying the money for this. Do you think this Reverse Osmosis Filter System is worthy enough against the investment you did? It completely depends on the quality that you are going to experience.
Know About Warranty and Return Policies
A lot of manufacturers are making products. A good amount of them are maintaining high quality as well. To make us known about those products, they make also creative advertisements. Everything is fine. But then arrives the matter of Warranty and After Sales Service. For many, it’s really a big deal and it is quite able to make a big difference.
Don’t forget to check the facts like warranty, guarantee, and obviously the return policy if there any. Nobody can claim that nothing will happen, no matter what the quality of that product is. Nothing lasts forever. But a minimum return of value you can expect from the Reverse Osmosis Filter System you are going to pay for. So, be careful about checking policies. You may get some companies who are so clever that they try to make people puzzled with their obscure and mystical policies. In that case, don’t hesitate to contact with their representative and ask about what you want to know.
Checking FAQs and Customer Reviews makes your job easier.
If you want to save your time precisely, then checking FAQ anwers and customer reviews can be utile for you. There are few common questions people asked before and they are answered as well is called the Frequently Asked Questions or FAQ. On the other hand, you will get a real life experience through the customer reviews in which they share their sotries about the product.
If you want to get a clear idea of both, checking out those two things are must. You may find there such informations which might not come in your mind to ask if you didn’t go through. You will be able to decide whether this Reverse Osmosis Filter System will come handy or not without any hesitaton.
Final Thought
One last word, don’t forget to consider the price you are paying for the Reverse Osmosis Filter System is logical enough against the value it is providing to you. Have you been able to gratified with that? Can you be able to fullfill your demands with that? That’s the thing that should get the most importance we guess.
Hope you have enojoyed this whole article which was actually a buying guide that will lead you to buy the best Reverse Osmosis Filter System. All the efforts we put here will get success when you will find this even a little bit of useful for you. At the end of the day, your satisfaction matters most to us.