The smallest reverse osmosis systems that we can find currently on the market are smaller than most cultivated watermelons! If you’re short on space but keen on improving the quality of your water, choosing a small reverse osmosis system is essential.

Smallest Sink Fixture RO Systems

The smallest reverse osmosis system that we’ve found is the proud invention of PuroSmart. You can only use this system with your sink as it fits right onto the faucet, rather than being installed underneath.

It’s only 8.25inches tall and is completely mobile. The tube design contains a carbon block pre-filter and a membrane for reverse osmosis – water is pushed through using the pressure from the water mains, rather than a pump.

Clip onto the tap, divert the tubes to wherever you need the water to go (a glass, for example) and turn the water on.

It can process through 57 liters of water per day and, according to PuroSmart, only needs filter changes once a year. It’s a very small and useful device, particularly when you’re on the go and need to filter water from hotel faucets.


smallest reverse osmosis system

For a permanent device, however, the smallest reverse osmosis system we found was the WECO Tiny system. It can process 163.6 liters of water per day from under your sink! It’s 16 inches at the tallest point and features a 30-micron polypropylene pre-filter, 5-micron solid-block activated carbon block cartridge and reverse osmosis membrane.

Besides your sink, it can also work wonders in bathrooms, showers, RVs, and boats. It’s our number one choice for a permanent, small reverse osmosis system.

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Installation and Maintenance

Installing the WECO Tiny is not rocket science, but it does take a little patience. Tubes are color-coded so you know where to connect everything up by using the under-counter installation kit to guide you. It can be wall-mounted or floor-standing, depending on the location you’ll be installing it in.

Maintenance is fairly simple. According to WECO, you’ll need to replace the pre-filters every 3 months, the post filter every year and the membrane every 2 years. You only have a limited 1-year warranty.

Where Can I Use the Smallest Reverse Osmosis System?

You can use the Tiny-36 system anywhere there’s space.

  • Under the sink,
  • Bathroom cabinets,
  • By the shower pump,
  • In apartments, houses, office buildings, cafés and businesses.
  • In RVs, cabins and holiday homes.

As a permanent system, you can’t move it around with you. If you’re looking for a travel-sized reverse osmosis system, take a look at the PuroSmart instead.