donald len bassman / email:

Cost of watering lawns in Seattle (2023)

To maintain a healthy and somewhat green lawn, thru the 3 hot, dry, summer months, you will need to cover the lawn area with about 1" of water per week. That works out to about 2/3 gallon per square foot.

The average marginal cost of residential irrigation water is about a penny per gallon. To water 1000 square feet of lawn for a month requires 2500 gallons of water and costs about $25.

I don't know the average lawn area of a residential lot - it could be twice the amount above.

With rising temperatures, many nice tree's and plantings may be lost unless they are watered.

An average person uses about 2500 gallons of water per month for their personal needs. The cost is about $90 though, due to wastewater surcharges.

Residential wastewater charges in Seattle are based on winter useage, so irrigation water theoretically does not incur additional wastewater charges.

Non-residential and multifamily users do incur the extra wastewater charge. Multifamily is generally considered 3 units or more, in Seattle.

Other cities, such as Bellevue, Redmond, and Kirkland, are wholesale customers of SWD, and set their own rates for water and wastewater.

Shoreline and parts of Burien also set thier own rates for wastewater.

Properties on separate irrigation meters do not incur wastewater charges.

It is something to think about that the Seattle area gets 4 times as much rainfall per year on a residential lot as it takes to maintain a lawn there. Much of it falls wasted on hardscapes.

Concrete manufacturers, and the Ship Canal, are among the biggest users of available water in the Seattle supply systems.

Local governments have become more proactive though, in requiring recycling systems for new construction.

Respectfully, Don

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