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Department of Health Services

Environmental Health and Safety

Proper Disposal of Public Pool, Spa and Filter Backwash Water

If you need to drain your public pool or spa or backwash your filter you will need to dispose of the water in the correct way.  Please read these guidelines for the proper way to dispose of your water or backwash.

Download Guidelines for Proper Disposal of Swimming Pool, Spa and Filter Backwash Water (PDF: 740 Kb)

Protect our creeks, rivers, lakes, ocean and groundwater. Do not discharge pool, spa or backwash water to a street or to a storm drain.

What's wrong with draining my pool or spa water or my filter backwash to the street or storm drain?

Street drainage and storm drains lead into streams, rivers, and other drainage waterways.  Chlorine, bromine, algicides, biocides, water conditioners, stabilizers and other chemicals in the pool water are toxic to fish and other aquatic life.  Diatomaceous earth (DE), cellulose fiber and sand particles from backwash water can fill in the spaces in the streambed gravel, preventing oxygen from reaching fish eggs and young fish.  DE and cellulose fiber can also clog fish gills.

To Drain Your Pool or Spa

If you are connected to city sewer:

  1. Locate the sewer cleanout on your property or an indoor drain such as a sink or bathtub.
  2. Using a hose, connect a siphon or sump pump that pumps 20 gallons or less per minute to the cleanout or indoor drain. Pumps are available at home improvement or equipment rental stores.
  3. Pump the water from the pool or spa to the cleanout or indoor drain. Contact your local public sewer provider 24 hours in advance if you are draining more than 100,000 gallons.
  4. Replace all cleanout covers when done.

If you are connected to a septic tank:

  1. Do not drain pool or spa water into your septic system, as it may cause system failure. Make sure the water is not cloudy, the pH is neutralized, and the chlorine or other disinfectant residual is below 0.1 milligrams/liter (parts per million).
  2. Discharge only onto a vegetated ground surface, taking care that there is no flow off your property. Use sandbags or berms, if necessary. Do not discharge onto saturated soils or areas where there has been a recent application of herbicides, pesticides, or fertilizers.
  3. Allow sufficient area to prevent ponding.

To Backwash Your Filter

  1. Backwash water must be collected, contained and discharged to the sanitary sewer, if available, or to a vegetated area contained within your property.
  2. Cartridge filters should be rinsed in a sink, bathtub, or over a lawn or other vegetated area.

Use a separation tank for diatomaceous earth (DE) and cellulose fiber filters to capture the DE or fibers. For water conservation, direct the clean water back into the pool.

Need More Information?

Pools & Spas

Your local pool or spa supply store or manufacturers can give you information or advice.

Commercial Plan Check, Permits, Inspections, Complaints:
Sonoma County Department of Health Services, Environmental Health Division:
(707) 565-6565

Stormwater Pollution Prevention:

Unincorporated Areas within Sonoma County:

Sonoma County Water Agency

(707) 526-5370

City of Santa Rosa:

(707) 543-3467

Public Sewer Agencies


(707) 894-1700


(707) 665-3631


(707) 433-3317


(707) 762-5892

Rohnert Park:

(707) 543-3370

Santa Rosa:

(707) 543-3370


(707) 543-3370


(707) 565-3638


(707) 838-1006

  • Septic Tank Questions
    Permit Sonoma: (707) 565-1900

  • California Department of Fish & Game
    (707) 944-5500