iSpring US31 3-Stage Detailed Product Review


The guys at iSpring are offering a great replacement for the much bigger reverse osmosis systems. The iSpring US31 is a 3-stage under sink system for an on-demand pure and healthy water.

The system complies strictly with FDA standards. It is additionally tested by an independent third party against NSF/ANSI standards 42, 53, 61. There’s a sediment filter to protect and extend the life of the other filters. And let’s not forget you won’t drink a lot of the unhealthy contaminants which typically reside in your water.

A great feature of this product is the clear filter housings that provide easy visual filter inspection.


iSpring US31 3-Stage Under Sink High Capacity Tankless Drinking Water Filtration SystemThe system uses a universal 10” sediment filter and 2×10″ carbon block filters. All three are 5-micron filters. At the first stage send, rust, particles, and dirt are removed which except for the purity of your water, help also for the longevity of the system itself.

The other two CTO carbon filters remove chlorine, VOCs, and common chemicals improving the water clarity, taste and removing the odors. They also remove hydrogen sulfide, heavy metals, giardia, Cryptosporidium. TDS, on the other hand, will not be removed so if you want those out of your water you might want to consider looking into other water filtration systems.

All three filters work well for about 6 to 12 months, depending on the usage and the contamination of your water. The capacity of the system is 2000 gallons. Depending on your source water pressure, the water flow will be up to 1 GPM. The maximum pressure for this system is 90 PSI.


The set includes the 3 filters with 3 filter cartridges, wrench, manual, faucet, tubes, feed water adapter, and fittings. The feed water adapter will supply water to the system from your cold water line, and the drinking water faucet is used to supply filtered water from the system.

The dimensions of the system are 16 x 6 x 16 inches and it weighs 12 pounds. You want to check the under sink measurements before purchasing.

Installation and maintenance

The kit comes ready for installation and with clear and easy-to-follow instructions. Depending on your knowledge about plumbing about water filtration installation, it could take from around 30 minutes to an hour. No matter you have or haven’t done that before, it’s good to check things under your sink first. And read the manual.

An important note is that the faucet requires 1/2″ hole and includes a cover plate that can fit up to 1 1/2″ holes. The system comes with 1/4″ hex and T-adapter for 3/8″ connections. But the manufacturer has adapters for 1/2″ connections so you might need to contact them before the purchase to arrange those.


  • High-quality, USA-made product
  • Certified against NSF/ANSI standards 42, 53, 61
  • 3 stages of filtration and longevity of filters
  • Visible inspection of filters


  • Leaks are possible in few occasions

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