Grade C-
Cost Performance
WQA to NSF 58

Not NSF Certified. Certified by WQA to reduce 16 contaminants including fluoride but not chlorine taste and odor. Reasonable system price and inexpensive replacement costs. Does not restore the healthy minerals lost in the reverse osmosis process.


From the manufacturer

The Watts Premier WP5-50 Reverse Osmosis Filtration System is innovative in its one piece manifold design, thereby providing a seamless water path, effectively eliminating 17 different connections. It is a 5 stage reverse osmosis system that is certified to industry standard with the reduction of the claims specified on the performance data sheet.

  • Reverse Osmosis Filtration System
  • 3-Gallon Storage Tank
  • Chrome Air-Gap Faucet
  • Adapt-A-Valve Water Shut-Off Valve
  • 50 GPD Membrane
  • Full Set of Filters

  • MFG Brand Premier
  • Certified by WQA to NSF/ANSI 58 Certified Reverse Osmosis Units*
  • *Includes Certification for Nitrate/Nitrite Reduction
  • *This product is intended for use only on water supplies that have been shown to be at or below the referenced concentration and valency of arsenic.


  • Model# WP5-50. Item Number 500057

Product Dimensions:
(Due to the individual fittings the exact measurements may vary slightly.)
  • Rack and Cartridges (16.0" W x 16.7" H x 4.8" D)
  • Tank (13.6" H x 11.0" D)


Customer Rating: 3.9 out of 5

Number of Reviews: 189

343 of 351 people found the following review helpful
4.0 out of 5 stars
Well Suited for Hydroponic Gardening, With Some Caveats, April 12, 2009
By Bob Kaufman
Verified Purchase(What's this?)
This review is from: Watts WP5-50 Premier Five-Stage Manifold Reverse Osmosis Water Treatment System (Tools & Home Improvement)
For an aspiring indoor hydroponic vegetable gardener like Your Humble Narrator, a source of clean water is essential. Here in suburban Salt Lake City, we are blessed with some of the dirtiest water in the country. Using this meter: pH-EC-TDS Meter my tap water clocks in with a pH of 8.2-8.4 and TDS (Total Dissolved Solids) reading of 300-350 ppm (parts per million). This review specifically addresses the suitability of the Watts WP5-50 reverse osmosis system to the task of providing a water supply for the home hydroponic gardener.
I've used other filtration devices, like straight carbon filters, and have been disappointed. Yes, they do remove sediment and some contaminants, however the drinking water never genuinely tasted "clean". Moreover, taking the testing meter to this water, and the TDS reading never went below 280 ppm which is unacceptable for hydroponic growing. After doing some research, I concluded that the only option was reverse osmosis.

Package Inspection

Out of the box everything looked okay with the exception of the faucet, which, as other reviewers have noted, is a cheaper version of the displayed product.


Installation was straightforward. The instructions, while not written by an English professor were sufficient albeit vague in a few critical places. I had the unit installed within two hours.

Waste Water, Output Water Quality and Quantity

My three biggest concerns with this product are output water quality, output water quantity and waste water production. Bear in mind that all of these are dependent upon the quality and pressure of your incoming water supply, which can change from season to season as well as from one time of day to another. Take a certain degree of comfort in knowing that my incoming water is probably worse than yours.

I have not yet connected the waste water tube to the sink's drain. Rather, the waste water tube is currently draining into an 18-gallon bucket so I can take measurements for the purposes of this review. To leave this setup in this manner is a code violation. I suggest that you connect your unit properly.

The amount of waste water this unit produces is staggering. For each gallon of clean water, I produce an additional 6.5 gallons of waste water. I have come to understand that I will experience a similar ratio regardless of the reverse osmosis unit I use. This phenomenon is a consequence of RO technology in general rather than a peculiarity of this particular unit. As I've suggested, the amount of waste water produced is proportional to how contaminated your incoming water supply is.

The output water quality is excellent. TDS (total dissolved solids) are 15-20 ppm, which is ideal for hydroponic growing. Any purer than that brings you into the realm of distilled water, which would need to be supplemented with minerals to be suitable for hydroponic use. Output water quantity is sufficient although disappointing. It produces one gallon in about 90 minutes. Higher water pressure and cleaner incoming water will decrease this time. The storage tank, although it has a physical capacity of three gallons, drains to empty after drawing two gallons. I consider this is a consequence of the technology, not a case of misleading advertising.


The Watts WP5-50 reverse osmosis water treatment system is well suited to the task of providing contaminant-reduced water for the purposes of hydroponic growing. It produces clean water in sufficient quantity for the purposes of a home hydroponic garden. Insofar as the waste water is concerned, for the time being, I'm leaving the waste tube in that eighteen gallon bucket. I'm using that water for my lawn.

June 20, 2009 - Important Update

Several weeks ago, our city's water changed for the worse. I'm assuming that it's because of a switchover to summertime procedures where water consumption is considerably heavier. Incoming water is now 800-900 ppm of Total Dissolved Solids. The unit's output water quality is 80-100 ppm which is still in the "good" range. It now produces roughly twelve gallons of waste water for each gallon of clean water is generates. The lesson here is that water quality can dramatically change from one season to another, as well as from one time of day to another.

2.0 out of 5 stars
Nice design but developes bad taste eventually
By Anthony Kempka on December 18, 2016
I've owned two of these units now and have had to throw them out. The overall design is good with a few exceptions. Good: single piece filter housing with no pipes connecting filters, 3/8" piping, and the older style faucet was great (the new owns not so much). Bad: eventually developed a plastic taste, final finishing carbon filter just flops around and isn't attached to the main single piece filter body, poor production quality with leaks. I'm not sure what is failing, but they both developed a plastic taste after a period of time. Yes, we're very careful to follow the manual for installation and maintenance. The first unit we purchased lasted over 6 years (mostly on city water) the second unit a little over 2 years on well water. It's important to note that the plastic taste came _after_ complete filter and RO membrane change (performed exactly as described in the manual).