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Where and in what order should a whole-house water filter be installed?

Install a whole-house water filter on the main incoming water line after the meter and main shut-off valve, but before the household branches and water heater.

Install a whole-house water filter on the main incoming water line, usually downstream of the water meter and main shut-off valve, but before the plumbing branch lines and the water heater. This point-of-entry position filters water before it is distributed through the home.

Position on the water supply

A typical layout is:

Water meter → main shut-off valve → filter → household branches and water heater

The water heater’s cold-water supply must branch off after the filter if you want the hot water filtered. Any pipe branching off before the filter will remain unfiltered.

An irrigation or outdoor-tap branch can remain upstream where filtered garden water is unnecessary. This can reduce demand on the filter.

The filter should have the correct flow direction, adequate pipe support and isolation valves for servicing. A bypass may also be appropriate. These requirements depend on the selected unit and pipe layout, so correct filter sizing for household flow should be confirmed before installation.

Do not assume every visible pipe near the meter supplies the whole house. A plumber should confirm the branch layout and keep the meter and main shut-off valve accessible.

Choosing a suitable location

Choose an accessible filter location with enough clearance to operate valves and remove the housing or cartridges. This access also makes scheduled cartridge replacement and filter maintenance safer and more practical. Follow the manufacturer’s requirements for mounting orientation, clearances and environmental protection.

The location should provide:

  • Independent support: Support the filled unit without relying on the connected pipework.
  • Weather protection: Protect the system from direct sun, heat, rain and impact.
  • Clear access: Keep it away from doors, paths and access to other services.
  • Safe drainage: Keep potential leaks away from electrical equipment and vulnerable finishes.

A garage, service area or protected external wall may be suitable if it meets these conditions.

The incoming service is pressurised. Homeowners should limit their involvement to identifying a possible location and maintaining access, as cutting or altering the pipe can cause flooding or contamination.

Have a licensed plumber complete the installation and confirm any applicable plumbing and backflow requirements. Contact our Sydney water-filter installation team to assess the incoming service and identify a safe, serviceable position.