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Condensate Disposal Requirements

This bulletin describes the condensate discharge requirements for air-conditioning units in residential, commercial, and industrial buildings. All installations shall comply with CSJ local ordinances and applicable sections of the California Plumbing and/or Mechanical Codes.

Residential Condensate Disposal Requirements – Drywell or Sanitary Sewer

  • The minimum size of a residential drywell is 2 foot square by 2 foot deep.
  • The nearest edge of the drywell shall be at least 3 feet from any structure or building foundation.
  • The drywell shall be filled with min. 1" gravel or crushed rock.
  • The top of the drywell shall be covered with building paper or plastic sheeting and 6" of earth cover.
  • The condensate pipe from the cooling coil (minimum 3/4") shall indirectly discharge into a minimum 1-1/2" drainpipe extended above grade near the edge of the foundation and terminate into the drywell.
  • Residential condensate drains that do not discharge into a drywell may terminate indirectly into the sanitary sewer system through a properly trapped and vented plumbing fixture in accordance with the California Plumbing Code.

Commercial & Industrial Condensate Disposal Requirements

  • Air-conditioning equipment condensate drains shall be trapped and vented per the conditions of the listing of the equipment and in accordance with the applicable requirements of the California Plumbing and Mechanical Codes.
  • Condensate from commercial & industrial air conditioning units must terminate in the following order:
    • i. To a landscaped area or stormwater treatment system (e.g. bio-retention unit) that is properly-designed to accommodate the volume of condensate; or
    • ii. To the sanitary sewer indirectly. Discharges to sanitary sewer system shall be subject to all wastewater permitting requirements and fees – contact the Environmental Services Department; or
    • iii. If the two discharge options described above are not feasible, as determined by the authority having jurisdiction, then these discharges may indirectly enter the storm drain system.

Secondary Condensate Drains

When a cooling coil is located in an attic, furred space, or other location where building damage could occur from a clogged primary condensate drainage system, a secondary condensate drainage system shall be installed to a point that is readily observable, or an approved water level detecting device shall be installed in accordance with the manufacturer’s installation instructions and the applicable sections of the California Plumbing and/or Mechanical Codes.

Note: Handouts are available at the Building Division Permit Center, which contain detailed residential and commercial/industrial condensate drywell specifications.

Additional information can be obtained by visiting our website at or by calling our Information Inspector's voice mail at (408) 535-7641 and leaving a detailed message.

In addition you may visit the Building Division in City Hall at 200 E. Santa Clara Street. Our hours are 9:00 a.m. to 4:00 p.m. with limited service between 12:00 p.m. and 1:00 p.m.

A PDF handout version of this information is available on our Building Handouts and Forms page.