Water Pumps & Treatment News

Reverse Osmosis Maintenance

At EDS Pumps & Water Treatment Ltd., we understand that certain routine reverse osmosis maintenance must be performed in order to ensure optimum efficiency. That is why we offer a wide range of reverse osmosis products and services.

Reverse Osmosis Systems

The standard reverse osmosis system consists of three stages: pre-filtering, the reverse osmosis process, and post-filtering.


Water flows from the water supply to the first stage, the prefilter, where the 5-micron cartridge removes sand, silt, dirt, and other sediments that may be in the water supply. From there, the water flows to the reverse osmosis membrane cartridge.

The Reverse Osmosis Process

Water is forced by pressure (at least 35 psi) through the semi-permeable membrane. The good water passes through the membrane (at two drops per second) to the storage tank, while the dissolved and particulate materials are sent down the drain. There must always have a certain amount of water continually flushing across the face of the membrane to clean the porous surface and prevent plugging. The amount of good (product) water and the amount of flushing (reject) water is called the reject ratio. For residential reverse osmosis systems this is usually around 3:1. In other words, reverse osmosis systems will require 4 gallons of water to make 1 gallon of purified water.


After leaving the storage tank, but before going to the faucet, product water goes through post-filtering. The post-filter or filters are usually made of a type of carbon designed to remove any remaining taste and odour.

Reverse Osmosis Maintenance Guide

The frequency of maintenance that a reverse osmosis system requires depends on a number of factors, including the condition of the water and level of use. To properly maintain your reverse osmosis system, you should:

  1. Every 4 to 6 months – Replace all filters, except the membrane.
  2. Every 36 months – Replace the membrane and disinfect the unit and tank.

Reverse Osmosis Filter Cartridge Replacement

To properly replace the reverse osmosis filter cartridge, you should:

  1. Shut off the water supply valve found underneath the sink. Follow the tube (right side of unit) to the angle stop and shut it off.
  2. Turn the valve on top of the storage tank to the off position.
  3. Open the product faucet by switching the handle to the upright locking position
  4. Unscrew each canister clockwise one at a time.
  5. Replace filter cartridge. (Handle each replacement filter cartridge by the shipping wrappers, or use nitrile gloves, for sanitary purposes.)
  6. Inspect canister o-rings for placement and proper lubrication.
  7. Tighten canister by hand only.
  8. Close product faucet.
  9. Turn both water valves back on and check for leaks.
  10. After you are certain there are no leaks in the system, drain the storage tank. It will then take from 2 to 6 hours to fill up again.
  11. Drain tank a second time and let refill.

Note: Additional point-of-use systems (e.g. ice makers) may use additional filters along with their cold-water supply line, which will also require separate maintenance. Refer to the appropriate owners’ manuals for full instructions.

At EDS Pumps & Water Treatment Ltd., we can assist you with reverse osmosis maintenance. We carry a full line of reverse osmosis filters and tools, so that you can perform this work yourself, or if your time is limited, just give us a call at 604-534-1115 and one of our certified Water Treatment Technicians can do the work for you. EDS Pumps & Water Treatment Ltd. has the most certified Water Treatment Technicians on staff in the province.