RKIN OnliSoft Pro Water Softener

Key Features:
  • Provides decent capacity for small families up to 3 people
  • No regeneration helps users save water effectively
  • Comes with detailed instructions for proper installation


Based in Florida, the company specializes in manufacturing whole house water treatment systems as well as air purifiers. The OnliSoft Pro is probably one of their best systems on the market today. It’s an innovative whole-house water treatment system that’s made up of a salt-free water softener and a water filter system, which together offer a comprehensive solution to a wide range of water quality issues.

The system can effectively remove many different contaminants present in water supplies and treat water hardness and prevent scale build-up in plumbing systems and home appliances. It comes in four different versions, OPX8 (for 1-3 bathrooms), OPX9 (for 2-3 bathrooms), OPX10 (for 4-6 bathrooms), and OPX (for 7+ bathrooms).

The only difference between them is the capacity/number of users and for that reason, we are going to look at the OPX8 in this review which is the base model. We will do it in a way that covers all the other versions as they are basically the same with regard to water filtration and softening performance. So, let’s start right away.

The Filtration Performance

The filtration system of the RKIN OnliSoft Pro performs really well when it comes to removing contaminants. It uses a 4-stage filtration process consisting of KDF media, carbon filter, EvenFlow bed, and a sediment filter which together efficiently remove most of the common contaminants found in water.

In the first stage, it’s the KDF media which features a combination of copper and zinc alloy that removes heavy metals such as mercury and lead as well as some harmful chemicals including chlorine and haloacetic acids. The copper and zinc alloy also create a bacteriostatic environment that helps prevent algae and bacteria growth within the main filtration tank.

The 2nd stage consists of catalytic activated carbon media sourced from coconut shells. It effectively removes most of the organic contaminants and disinfectant by-products which include chlorine, chloramines, VOCs, herbicides, pesticides, sulfur, haloacetic acids, MTB & THM’s, and many more. This media efficiently clears out more than 99% of chlorine and other chemicals present in the water, significantly improving the water’s taste and odor.

The carbon filtration tank of the RKIN OnliSoft Pro is equally equipped with an EvenFlow bed which is RKIN’s innovation that helps eliminate channeling and substantially increases the contact time between the water and the filtration media – this ensures optimum utilization of the filter media and thorough treatment of the water.

From the carbon filtration tank, the water is directed to the ZEE Pro Pre-filter which makes up the 4th stage of the filtration process of this RKIN OnliSoft Pro system. This sediment filter is a separate component that sits between the carbon filtration tank and the RKIN’s OnliSoft water softening tank. It effectively filters out all the sediments that are larger than 5 microns which include silt, clay, sand, rust, and any other small particle that might be lurking in the water.

The housing of the ZEE Pro Pre-filter has also been designed with bacteriostatic technology hence no bacteria or algae will be growing inside there.

Water Softening Capability

The RKIN OnliSoft Pro offers an entirely salt-free water softening process using its OnliSoft water conditioner which is an effective SCM (scale control media) that naturally neutralizes the minerals that cause water hardness through Seed Assisted Crystallization.

As more and more hardness minerals continue to be transformed, the tiny modified molecules accumulate and build upon the surface of the OnliSoft media. Eventually, they reach a certain size where they break off from the media’s surface and get suspended in the water, and ultimately carried away – they flew through the plumbing system and appliances without sticking to them.

It’s an all-natural process of preventing scale build-up. No chemicals, salt, or acids are added to the water, and not only does the OnliSoft media inhibits scale from forming, but it also reverses scales that have already built up within the plumbing system.

The other advantage is that the hardness minerals are not totally removed from the water – they are only inhibited from forming scale, so your filtered water will still have them which is great because they are healthy minerals that are quite beneficial to your health.

With this really impressive water conditioning system coupled with an effective filtration process, the RKIN whole house filter system is able to provide clean, great-tasting drinking water throughout your entire home, water that’s equally soft on your skin and hair as well as safe for your appliances and plumbing system.

Many reported that they noticed the difference in their water quality right away. They said that it doesn’t leave stains on appliances anymore and the chlorine smell and taste are all gone, plus the water looks so much clearer. The system removes over 99.66% of chlorine and many other contaminants. Several users also mentioned that they noticed existing scale build-up clearing out from their plumbing system after installing this RKIN OnliSoft Pro unit in their home.

However, despite having an effective filtration system, you can only use this RKIN system to filter water from a city/municipal water supply. It’s not suitable for use on well water or any water that’s microbiologically unsafe.  

System Capacity

Apart from the very effective water treatment system, the carbon filter media of the RKIN whole house filter system offers a large capacity. It can process up to 500,000 gallons of water which is roughly 10 years of service for a house with one to three bedrooms or a small-medium family with average water consumption.

Furthermore, even with the multiple stages of filtration and a water conditioning stage, this system doesn’t seem to drastically affect the water flow. It’s able to maintain a standard flow rate of 9 GPM which can go up to 12 GPM during peak times – there’s basically no significant drop in the water pressure once you install the system.

As mentioned earlier, RKIN also offers three other different versions of this whole house filter system which you can consider if you have a large house or looking for more capacity and a faster water flow rate. There’s the OPX9 which offers 1 million gallons capacity and an 11 GPM service flow rate (goes up to 17 GPM at peak times) – it’s meant for houses with two to five bathrooms.

The second one is the OPX10 which offers 1 million gallons capacity too but with a service flow rate of 15 GPM (that goes up to 23 GPM at peak times) and this is ideal for houses with 4 to 6 bathrooms.

The third version is the OPX13 and this also offers 1 million gallons capacity but has the highest service flow rate at 28 GPM (which can go up to 41 GPM at peak times).  This one is ideal for large houses that have more than seven bathrooms.

The best part of this system is that, unlike salt-based systems, it doesn’t produce any wastewater because the media doesn’t require any regeneration. Hence, no salt or chemicals will be dumped into your drain.

Moreover, it doesn’t use electricity and since all the water that goes through it gets processed and flows right into your home, there’s no water wasted, thereby it saves you both electricity and water cost that you would have otherwise incurred if you installed a salt-based water softener.

Installation and Maintenance 

Installing this RKIN OnliSoft Pro system is relatively easy, but it may need some plumbing knowledge because it has to be installed on your main water supply line which means you may have to alter your piping/plumbing system a little bit.

You can do it yourself if you have some basic DIY skills but you’ll need an extra pair of hands to help you, especially with mounting the ZEE Pro pre-filter – you need someone to hold it in place while you screw the mounting bracket onto the wall. If you’re not good with DIY installations, then you may need to get a plumber to help you set up the system.

The whole installation process can take roughly 3 to 5 hours. The system should only be installed to the cold water line, not hot water as it can only handle operating temperatures of 36 to 120°F. The recommended operating pressure is 25 to 120 PSI.

RKIN provides almost everything you need for a successful installation. The package includes the Carbon and OnliSoft tanks, the ZEE Pro pre-filter and its housing, two bypass valves, four 1-inch MNPT PVC elbow fittings, hose bib assembly, and mounting kit for pre-filter housing (the mounting bracket, washers, and hex bolts).

The package includes too the installation manual with clear and easy-to-understand instructions that take you to step by step throughout the whole process. RKIN also offers an optional installation kit to make the installation even easier and it includes two 1-inch male NPT nipples for the ZEE Pro pre-filter housing, two stainless steel 24 x 1 inch quick connect supply flex hoses, and two stainless steel 18 x 1inches water tank connector hose.

Once installed, maintaining this RKIN OnliSoft Pro whole house filter system is pretty simple. It produces zero water waste, needs no electricity to operate, and doesn’t require the yearly maintenance and cost (of buying salt regularly) that’s involved with standard salt softeners.

The only maintenance you’ll need to do is replacing the media in the sediment pre-filter housing which requires changing every 6 to 12 months based on the amount of sediment and particles present in your water supply or when you notice the pressure of the water from the system starting to slow down.

You won’t be changing the carbon media any time soon because as we mentioned earlier, it has a large capacity of 500, 000 gallons which can last up to 10 years if you are a medium-sized family in a house with 3 bathrooms and your daily water consumption is average (around 100 to 150 gallons a day).

The OnliSOft media, on the other hand, is non-absorbent and will last for a lifetime, hence needs no replacements or maintenance. However, the whole system will require care and cleaning, at least after 5 years or less.

The build quality of the tanks, connectors, and the other parts of the system is quite good. Everything appears to be robust and well built – they are not likely to break or get damaged easily. The mounting bracket for the ZEE Pro pre-filter housing is a thick aluminum too and RKIN provides large hex bolts for mounting it on the wall, so it will firmly stay put and hold the pre-filter in place once mounted.

The tanks (with the head attached) measure 8 inches wide and 48 inches high, hence they don’t take up much space. They can be installed even on uneven surfaces because they sit in a “boot” which allows you to adjust their position if either of them doesn’t stand perfectly straight up and down – the bottom of the tanks is round, so the boots allow them to stand upright and sit firmly once adjusted properly.  

Final Remarks 

From our thorough assessment, the RKIN OnliSoft Pro whole house filter system is a suitable option for anyone looking for a comprehensive water treatment system that can deal with water hardness and also effectively remove most of the common contaminants found in the water.

It’s particularly ideal if you are after a salt-free water softener that can handle both medium and very hard water from the city water supply – especially if you need to monitor your sodium intake or have cardiovascular issues. It doesn’t use any salt or chemicals to soften the water and the results are just as good as when using a salt-based system.

There are no serious drawbacks to worry about either. The only thing is that you can’t use it on well water or any water that might be microbiologically unsafe. It’s designed to filter only water from a municipal water supply.

The system comes with very impressive warranty terms. RKIN offers a lifetime warranty on the tanks and the parts, as well as a 1-year money-back guarantee. The customer support from the company is also impressive as many users attested that they respond quickly and always answer customers’ queries or resolve any problems. You can reach them by phone or e-mail.

Things we like

  • Provides decent capacity for small families up to 3 people
  • No regeneration helps users save water effectively
  • Comes with detailed instructions for proper installation
  • Can remove most contaminants thanks to 4-stage filtration process
  • Friendly customer service and quick response to questions
  • Backed by 1-year money-back guarantee, lifetime warranty on tank and parts

Things we don't like

  • Comparably high price
  • Not suitable for use with well water or microbiologically unsafe water

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