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RKIN Flash Undersink Reverse Osmosis System with Chrome Lead-Free Faucet

RKIN Flash Undersink Reverse Osmosis System with Chrome Lead-Free Faucet

24 reviews
Regular price $299.45
Regular price $499.95 Sale price $299.45
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Post Filter Option
  • Enjoy the peace of mind that comes with up to 99% removal of contaminants, including fluoride, chlorine, and heavy metals
  • Choose from our AlcaPure or OnliPure editions for alkaline pH or zero TDS filtration options
  • Trust in our NSF/ANSI 58 certified reverse osmosis membrane, 1-year warranty, 1-year satisfaction guarantee
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        RKIN Water Systems As seen on AMC's NewsWatch TV

        Flash undersink reverse osmosis filter system

        Delicious Purity

        AlcaPure Post-Filter has a small amount of Calcium and Magnesium Minerals returned back to purified water to give you a taste comparable to your favorite bottled water: Alkaline 7-8pH, with beneficial minerals added.


        OnliPure Post-Filter brings the TDS reading to zero. Zero TDS or Total Dissolved Solids is perfect for people who want Absolute Purity.

        RKIN Flash Undersink Reverse Osmosis System with Chrome Lead-Free Faucet - RKIN

        Efficient Filtration

        75-Gallon Per Day Reverse Osmosis Membrane delivers 50% faster pure water production compared to most other undersink reverse osmosis water filters.

        RKIN Flash Undersink Reverse Osmosis System with Chrome Lead-Free Faucet - RKIN

        Sanitary Filter Replacements

        Quick and easy twist-on and-off filter replacements without the need to drain filter housings and deal with leaky o-rings.

        RKIN Flash Undersink Reverse Osmosis System with Chrome Lead-Free Faucet - RKIN

        Non-Electric Operation

        The pump-less operation makes the filtration process the quietest in the market without using any electricity.

        This light weight system can be mounted under the sink or secured in place with velcro.

        Flash undersink reverse osmosis system space saving design

        Space Saving Design

        Undersink space is in very high demand, and your undersink water filter should not be taking up most of it.

        Flash R.O. system's slim design and the small tank will allow for more storage space.


        Flash R.O. Dimensions - W 5.5", L 14", H 16"
        R.O. Tank Dimensions - W 11", L 11", H 14.5"
        R.O. Tank can be placed vertically or horizontally

        Flash undersink reverse osmosis system lead free faucet

        Chrome Lead Free Faucet

        Chrome Gooseneck Leadfree faucet with easy-to-use bat-style handle makes filling up drinking glasses and whole pitchers effortless.

        How to use a TDS Meter by RKIN

        What are total dissolved solids or TDS?

        Total Dissolved Solids Or TDS is a measure of the dissolved combined content of all inorganic and organic substances present in a liquid. TDS is sometimes referred to as parts per million (ppm). You can test water quality levels using a digital TDS meter.

        Primary sources for TDS in Receiving Water
        are agricultural & urban runoff, clay-rich mountain waters, leaching of soil contamination, & point source water pollution discharge from industrial or sewage treatment plants.

        TDS in parts per million (PPM)

        • Flash undersink reverse osmosis filter

          Reverse Osmosis System with Filters

        • Flash undersink reverse osmosis system lead free faucet

          Lead-Free Faucet

        • Flash 3.2 Gallon Storage Tank

          3.2 Gallon Storage Tank

        • Flash 1.5 Drain Pipe Saddle

          1.5" Drain Pipe Saddle

        • Flash Tank Shut-Off Valve

          Tank Shut-Off Valve

        • Flash Faucet Adapter

          Faucet Adapter

        • Flash Tee for Refrigerator Connection

          ¼" Tee for Refrigerator Connection

        • Flash tubing

          ¼" and ⅜" Tubing

        • Flash Comp or NPT Diverter Valve

          ⅜" Comp or ½" NPT Diverter Valve

        • Installation and Product Manual

          Installation and Product Manual

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        Flash reverse osmosis filter installation

        Frequently Asked Questions

        Who installs my RKIN Water System?

        RKIN ships direct from the factory, saving you over 60% of the standard retail cost. Our products' user-friendly design makes installation easy with or without professional help. However, if you're not mechanically inclined, we do recommend hiring a plumber to help with installation.

        What are the dimensions of the Flash Reverse Osmosis Filter?

        A: Flash R.O. Dimensions - W 5.5", L 14", H 16", R.O. Tank Dimensions - W 11", L 11", H 14.5", R.O. Tank can be placed vertically or horizontally.

        Does the Flash R.O. System need an electrical outlet?

        No, the Flash R.O. system doesn't have an electric pump but instead uses the natural flow rate of your water supply to channel the water through the filtration process. Therefore, the Flash R.O. system doesn't require electricity to operate.

        Can I use another faucet other than the one that comes with the system?

        Any faucet specifically made for RO systems with a 1/4" connection would work with the Flash RO system.

        What is the difference between AlcaPure and OnliPure Editions?

        AlcaPure Edition post filter returns Calcium and Magnesium minerals back to water once it has been purified by Reverse Osmosis membrane. This increases the pH to an alkaline level, similar to spring water.

        OnliPure Edition post filter does exactly the opposite - reduces even the tiniest amount of TDS left over after the Reverse Osmosis to zero. This provides lab-grade purified water quality similar to distilled water. Slight variations in the calibration and accuracy of different TDS meters may result in the TDS reading of 1 or 2 PPM. 

        For most people, AlcaPure Edition Zero Installation Purifier is the right choice unless you have been accustomed to distilled water taste.

        What if I want to switch post-filters of the Flash R.O. later?

        Switching from the AlcaPure edition to the OnliPure edition, or vice versa, is as easy as ordering a different post-filter.

        How often do the filters need to be changed and how much do they cost?

        Please refer to the section below for all details on the replacement filters.

        Getting an abnormal filtered water taste is a good indication that the post-filter has been exhausted and needs replacement.

        How do I order replacement filters?

        If you sign up for the filter subscription program during checkout, the replacement filters will be delivered to you every 12 months automatically. Otherwise, replacement filters can be ordered on our website or over the phone.

        Does this system use proprietary filters available only from RKIN and reseller partners?

        Yes, we designed our own filters to make filter changes as easy as possible.

        Consumables and replacement cartridges

        Your water quality may affect the longevity and replacement frequency of the filters.

        First Stage Filtration - 5 Micron Filter. MPN: RC-FT-82. Replace every 12 months or as needed.

        Second and Third Stage Filtration - Carbon Block Filter. MPN: RC-FT-92. Replace every 12 months or as needed.

        Fourth Stage Purification - 75 Gallon Per Day RO Membrane. MPN: ZIPM75. Replace every 24 months or as needed.
        Hardness over 10 gpg (171 mg/L) may reduce the lifespan of the RO membrane. If the filtered water production decreases over time, please replace the RO membrane and substitute 2nd stage Carbon Block filter with a PPH Anti-Scale Carbon filter, MPN: RC-FT-90, to prevent premature RO membrane failure due to hardness build-up.

        Fifth Stage - AlcaPure Post Filter. MPN: RC-FT-87. Replace every 12 months or as needed. OnliPure Post Filter. MPN: RC-FT-OP. Replace as needed.
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        Collapsible content


        If the water being filtered is from a public water supply, it will comply with requirements, and your RKIN Flash Undersink Reverse Osmosis System will substantially improve the water quality.

        • For indoor non-commercial applications only
        • Protect from excessive cold or heat: do not expose to temperatures below 39°F (4°C) or above 113°F (45°C).
        • Flash R.O. Dimensions - W 5.5", L 14", H 16"
        • R.O. Tank Dimensions - W 11", L 11", H 14.5"

        Inlet water quality limits:

        • Max Total Dissolved Solids (TDS) 800 mg/L
        • Max Hardness 25 gpg (428 mg/L)
        • Sulphide, Iron & Manganese <0.1 mg/L
        • Chlorine <4 ppm, pH 3-11, Turbidity 5 NTU Max

        Shipping & Delivery

        Free standard shipping within the contiguous United States(lower 48 states).

        Orders are usually shipped the same or the next business day and delivered within 2-5 business days. Subject to in-region item availability and seasonal carrier shipping performance.

        Order tracking numbers are emailed as soon as they become available. If you do not receive your tracking number within 24 business hours, please check your spam folder.

        Price Match Guarantee

        We work diligently to make sure that we offer the best prices for our products online. If you come across another retailer offering a lower price for our products than we are within 12 months of your purchase date, please let us know, and we will refund you the difference in price.

        We want you to feel confident that you are getting the absolute best price for the product you are ordering from us. If you find that our own website,, has lowered the price for the same item you ordered within 12 months of your purchase date, please let us know, and we will refund the difference in price.

        Warranty & Returns

        You get an unconditional 1-year satisfaction guarantee, which includes a warranty for the same period.

        Free shipping on warranty replacements. Learn more