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Public Health
Seattle & King County
401 5th Ave., Suite 1300
Seattle, WA 98104

Phone: 206-296-4600
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Toll-free: 800-325-6165

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Instructions to submit a Public Records Request

How to be water-wise when you have a septic system

Key areas of your house can make significant impacts on your septic system. Learn more about how to be "water-wise".

Be water-wise in the bathroom

Did you know that toilet flushing uses the most water in indoor residential water use? Each person flushes 18.5 gallons per day!* Also, toilets, showers and faucets represent more than 70% of indoor water use.

You can lower your water use in the bathroom by following these easy tips:

  • Quickly repair all leaky faucets and toilets. This is one of the easiest ways to be water-wise. Slow leaks, such as a slowly dripping faucet, can generate 15 to 20 gallons (57 to 76 liters) of wastewater per day.*

  • Use "low flow" fixtures on faucets and shower heads (these may be found at most hardware stores) Some examples are:
    • Faucet insert: device that slows water flow
    • Faucet aerator: device that adds air to spread the water flow
    • Reduced flow faucet: the faucet is built for low water flow
    • Mixing valves: one fixture regulates hot and cold water

  • Take shorter showers.

  • Turn off the water while brushing teeth or shaving. Fill your sink halfway with water to rinse your razor.

  • Don't use your toilet as a garbage can. Flush only bodily wastes and toilet paper.

Number of bedrooms affect septic design

The size of your septic system is determined by several factors, including the number of bedrooms in the home. In King County, the minimum size septic tank is 1,000 gallons for 1, 2 or 3 bedrooms. Additional bedrooms require 250 gallons per bedroom.

Keep cars and trucks off drainfield and septic tank

Be sure to park your car in the garage or driveway. It will prevent soils from being packed down and pipes from breaking. Also, remember to direct guests' cars away from the drainfield and septic tank when you have a reunion, graduation party, garage sale, etc.

Be water-wise in the kitchen

Helpful tips to save water in the kitchen:

  • Run only full loads in the dishwasher
  • Don't run the dishwasher and washing machine at the same time
  • Keep water in the refrigerator to avoid running water until it gets cold
  • Don't run the water while washing dishes
  • Rinse fruits and vegetables through a colander into a bowl, then use leftover water to water your houseplants
  • Keep faucets tightly closed
  • Use 'low flow' fixtures on faucets (these may be found at most hardware stores)
    Some examples are:
    • Faucet insert: device that slows water flow
    • Faucet aerator: device that adds air to spread the water flow
    • Reduced flow faucet: the faucet is built for low water flow
    • Mixing valves: one fixture regulates hot and cold water
  • Quickly fix leaky faucets

Be water-wise in the laundry room

Helpful tips to save water in the laundry room:

  • Use the load size setting and proper water temperature
  • Run full loads in the washing machine
  • Don't run the dishwasher and washing machine at the same time
  • Consider a water efficient washing machine
  • Powder or liquid laundry detergent? Click here for the answer

For more laundry tips, visit the Washington Sea Grant Program's website.

Indoor residential water use

Pie chart indicating amount of indoor residential water use


*Information based on the USEPA Onsite Wastewater Treatment Systems Manual.