Rainwater Catchment

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WHAT IS A RAINFALL CATCHMENT SYSTEM?
Rainfall catchment systems include rain barrels, tanks or cisterns and associated piping. These systems can be used to collect and temporarily store rainwater, reducing runoff flow from properties and providing an alternative to using drinking water for non-human consumption purposes.


An example of a rain barrel

WHY USE A RAIN BARREL?

  • Reduces runoff and pollution from your property;
  • Conserves water and reduces water bill by providing free water for landscaping uses.

DO I NEED A WATER RIGHT PERMIT?
Collecting rainwater does not require a water right permit if used on the property where it is collected (RCW 90.03).

WHAT ARE THE GUIDELINES FOR RAIN BARRELS?
Rainfall catchment tanks no greater than 600 gallons shall be allowed to extend into a required yard setback if:

  • Each tank is less than four (4)-feet wide (measured perpendicular from the side of the house);
  • A minimum clearance of three (3) feet from the lot line is maintained;
  • The cumulative coverage of the tanks does not exceed 10% of each yard area.

Tanks larger than 600 gallons may be permitted in a required setback if:

  • They do not exceed 10% coverage of any required yard;
  • They are not located closer than three (3) feet from a side or rear lot line, or 15 feet from the front lot line;
  • They are screened, if located at the front of the property.


An example of an underground cistern system

In addition, rainfall catchment systems may not impede requirements for:

  • Lighting
  • Open space
  • Minimum usable yard space
  • Fire protection
  • Egress

Rainfall catchment systems should not obstruct any escape windows or create a surcharge on an existing retaining wall (TMC 13.06.602.A.4.m.12).

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