Water filtration systems for buildings

Buildings use water filtration and treatment to protect people, plumbing and equipment: removing sediment, reducing hardness and scale, improving taste and odour, and in some cases disinfecting. The right system depends on what is actually in your water and what you need it for, which starts with a water test. Any system you install must then be maintained, or it can make water quality worse.

Start with the water and the goal

Most buildings in Canadian cities receive treated municipal water that meets drinking water guidelines. Filtration in these buildings usually addresses specific concerns: hardness, chlorine taste, sediment from old mains, or water quality for particular equipment. Buildings on private wells have more to consider, since the owner is responsible for treating the water to a safe standard. Health Canada publishes guidelines for drinking water quality, and provinces set their own rules, particularly for public and commercial water systems.

Before choosing equipment, test the water and define the goal. Treating for problems you do not have wastes money and adds maintenance.

Common types of treatment

Point of entry and point of use

Point-of-entry systems treat all the water entering a building. Point-of-use systems treat water at a single tap, such as a drinking fountain or coffee station. A building may use both: a softener at the entry to protect water heaters, and carbon or reverse osmosis at drinking water points.

Filtration for equipment

Water quality affects mechanical equipment as much as people. Boilers, closed heating and cooling loops, cooling towers, humidifiers, dishwashers and process equipment each have their own water requirements. Scale reduces heat transfer and efficiency; corrosion shortens equipment life. Water treatment for these systems is usually handled by a water treatment provider and should be documented. See Legionella and cooling towers for one important example.

When filters become the problem

Neglected treatment equipment can harm water quality:

• Saturated carbon filters can release captured contaminants and grow bacteria.
• Cartridges left too long can clog, reduce flow and harbour biofilm.
• UV systems with dirty sleeves or expired lamps stop disinfecting without obvious signs.
• Bypassed equipment gives a false sense of protection.
• Softeners that are set wrong can waste salt and water, or fail to soften.
• Removing chlorine at the building entry reduces protection against bacterial growth in the building's plumbing downstream.

A maintenance routine

• Keep an inventory of all treatment equipment, with locations and model numbers.
• Label each unit with its last service date and next due date.
• Follow the manufacturer's replacement intervals for cartridges, media, membranes and lamps.
• Check pressure gauges before and after filters to spot clogging.
• Check that bypass valves are in the correct position.
• Test water periodically to confirm the system is still doing its job.
• Keep records of service, test results and any problems.

A typical case

A small office building on municipal water has scale building up in its water heaters and a complaint about chlorine taste at the staff kitchen. A contractor proposes a whole-building carbon filter and a softener at the water entry.

Working through the steps above, a water test confirms hard water but nothing else of concern. Softening at the entry makes sense to protect the water heaters. Whole-building carbon does not: it would remove the chlorine residual that protects the building's piping from bacterial growth, especially in parts of the building with little water use. A point-of-use carbon filter at the kitchen tap solves the taste complaint without that trade-off.

The owner then needs a maintenance plan for what is installed: salt for the softener, cartridge changes at the kitchen filter, and a record of each service. Without that, both units will eventually stop working without anyone noticing. A follow-up water test a few months later confirms that the softener is doing its job and that the kitchen filter has not been forgotten.

Questions to ask before installing

• What did the water test show, and which result is this equipment meant to fix?
• Will it treat all the water or only some outlets, and does it remove the disinfectant residual?
• What maintenance does it need, how often, and who will do it?
• What does each replacement cartridge, membrane, lamp or bag of salt cost over a year?
• How will we know if it has stopped working? Is there a gauge, indicator or alarm?
• What backflow protection does the installation need, and does it need a permit?
• For reverse osmosis, where does the reject water go and how much is there?

Protecting the public supply

Treatment equipment connected to the plumbing must be installed so that it cannot contaminate the public water supply. That usually means appropriate backflow prevention. Our guide to backflow prevention and testing explains the requirements. Installation should be done by licensed plumbers following the plumbing code and local bylaws.

How ehZee can help

Our air and water filtration system inspections look at your water treatment equipment, its condition and maintenance records, and whether it suits the building's needs. We report what we find and help you coordinate testing and licensed contractors where action is needed.

Common questions