Sewer
Residential rate: $13.54 per 100 cubic feet of water use
Non-residential rate: $14.00 per 100 cubic feet of water use
What it covers: This charge covers the cost of operating and maintaining the network of pipes and pump stations that moves wastewater from households and businesses to wastewater treatment facilities.
How sewer charges are calculated
For residential customers (single-family or multi-family): Sanitary sewer charges are based on actual water use, class average, or winter average, whichever is less.
- Actual water use: Measured through your water meter.
- Winter average: Your average water use during winter billing periods.
- Class average: The average water use for your customer class type (e.g., single-family home), used when no water use history is available. Class average volumes can be found on the full list of rates and charges.
For non-residential customers: Charges are based solely on actual water consumption measured through your water meter.
How winter average is calculated
For residential customers, winter average reflects indoor water use during colder months, which is typically when most water is used indoors and is entering the sewer system. Winter average volume is applied to residential accounts during billing periods outside the winter average period. This helps ensure you’re not charged sewer fees for water used on lawns or gardens and is not entering the sewer system.
Billing periods used:
- Quarterly accounts: February 1 – April 30
- Bi-monthly accounts: January 1 – April 30
- Monthly and budget billing accounts: December 1 – April 30
How to calculate:
- Find your water use (in ccf) during your winter review period.
- Divide by the number of days between meter readings.
- Multiply by:
- 90 for quarterly accounts
- 60 for bi-monthly accounts
- 30 for monthly or budget billing
Quarterly billing example:
- Water used: 12 ccf
- Days in period: 94
- 12ccf ÷ 94 days x 90 days = 11.5 ccf
Monthly billing example:
| Month | Water use (ccf) | Days in month |
|---|---|---|
| December | 12 | 31 |
| January | 12 | 31 |
| February | 11 | 28 |
| March | 12 | 31 |
| April | 12 | 30 |
| Total | 59 ccf | 151 |
- Add up your winter water use:
12 + 12 + 11 + 12 + 12 = 59 ccf - Total number of service days:
31 + 31 + 28 + 31 + 30 = 151 days - Calculate your daily average:
59 ÷ 151 = 0.3907 ccf per day - Multiply by 30 (for monthly billing):
0.3907 × 30 = 11.7 ccf
Minimum use billing
If your winter water use is very low (0–2 ccf), a minimum winter average is applied based on your billing frequency.
- Monthly accounts
- If winter use is 0 ccf, the assigned winter average is 2 ccf per billing period.
- Bi-monthly accounts:
- If winter use is 0 to 1 ccf, the assigned winter average is 5 ccf per billing period.
- Quarterly accounts
- If winter use is 0 to 2 ccf, the assigned winter average is 7 ccf per billing period.
- Multi-family, quarterly accounts:
- If winter use is 0 to 2 ccf, the assigned winter average is 5 ccf per dwelling unit per billing period.
Stormwater service unit
Rate: $6.310 per service unit per 30 days
What it covers: This charge covers the costs of operating and maintaining storm drains, pipes, ditches, outfalls, natural areas, and green streets that prevent pollution and reduce flooding by collecting and managing rainwater runoff.
What are stormwater service units?
Stormwater service units are used to calculate monthly stormwater charges. They represent your property's contribution to the city's stormwater system, based on the number of dwelling units (residential) or the amount of stormwater billable area (commercial and industrial).
Single-family residential properties
Single-family residential properties also include duplexes and properties with an accessory dwelling unit (ADU). Each dwelling unit is counted as one full stormwater service unit.
- 1 dwelling unit = 1 stormwater service unit
- 2 dwelling units (house and ADU) = 2 stormwater service units
Mixed-use and multifamily residential properties
Mixed-use and multifamily residential properties includes properties with three or more dwelling units, such as triplexes and apartment buildings, and those with mixed commercial and residential units.
For mixed-use and multifamily properties, service units will be billed at 0.65 for each dwelling unit. Analysis indicates that multifamily units, on average, have fewer people per unit than single-dwelling units.
- Each dwelling unit = 0.65 stormwater service units
- Total service units = number of units × 0.65
- Example for a fourplex: 4 units × 0.65 = 2.6 stormwater service units
Non-residential properties
Non-residential properties include commercial, industrial, institutional, and other properties without dwelling units. These properties are billed based on their stormwater billable area (impervious surface area). The calculation uses 2,400 square feet as a baseline, representing the average stormwater billable area of a Portland home.
- Stormwater service units = total stormwater billable area ÷ 2,400 sq ft
- Example for commercial site with 136,000 sq ft of stormwater billable area: 136,000 ÷ 2,400 = 56.67 stormwater service units
Stormwater billable area
Rate:
- Residential: $14.013 per 1,000 square feet of stormwater billable per 30 days
- Non-residential: $14.300 per 1,000 square feet of stormwater billable per 30 days
- Managed floodplains: $11.990 per 1,000 square feet of stormwater billable per 30 days
What it covers: This charge covers the costs of operating and maintaining storm drains, pipes, ditches, outfalls, natural areas, and green streets that prevent pollution and reduce flooding by collecting and managing rainwater runoff.
What is stormwater billable area?
Stormwater billable area is the developed area of a property. Development prevents stormwater from flowing or soaking into the ground naturally. Stormwater billable area includes areas like rooftops, porous pavement, patios, and driveways.
Single-family residential
Residential properties are divided into one of three categories based on the amount of stormwater billable area on the property. Properties with less stormwater billable area are billed less, while those with more are billed more.
| Small Category | Standard Category | Large Category |
|---|---|---|
| *1,500 square feet or less of stormwater billable area. | 1,501 to 2,700 square feet of stormwater billable area. | 2,701 square feet or more of stormwater billable area. |
*Where there are three or more individually metered single-family dwellings on one tax lot, the City will bill each dwelling 1,000 square feet per unit.
Please note: Overwater structures, such as floating homes and docks are not included as stormwater billable area.
If you believe your assigned category should be different, you may be able to request a change to your category.
Multi-family residential, mixed-use, and non-residential properties.
The total stormwater billable area for multi-family residential, mixed-use, and non-residential properties is measured and used to calculate the number of stormwater services units.
Customer calculation examples
The examples below show how your sanitary sewer, stormwater service units, and stormwater billable area charges are calculated. These example calculations reflect how different factors, like your water usage, number of dwelling units, and amount of stormwater billable, affect your monthly bill.
Single-family residential customer
Sanitary sewer: $13.54 per 100 cubic feet of water use
Stormwater service unit: $6.310 per service unit per 30 days
Stormwater billable area: $14.013 per 1,000 square feet of stormwater billable per 30 days
The example below is for a single-family residential customer who used 12 ccf (one ccf equals 100 cubic feet), has one dwelling unit, is in the standard category, and is billed quarterly.
The example below is for a single-family residential customer who used 12 ccf (one ccf equals 100 cubic feet), has one dwelling unit, is in the standard category, and is billed quarterly.
| Charge | Calculation | Total |
|---|---|---|
| Sanitary sewer | $13.54 x 12ccf | $162.48 |
| *Stormwater service unit | $6.310 x 3 | $18.93 |
| **Stormwater billable area | ($14.013 x 2.4) x 3 | $100.89 |
| Total sewer and stormwater charges | $282.30 |
*The stormwater service unit rate is per 30 days. In the calculation above, it is multiplied by three to represent a 90-day or quarterly billing period.
** The stormwater billable area rate is per 1,000 square feet per 30 days. In the calculation above, the rate is first multiplied by 2.4 (standard category is billed at 2,400 square feet) and then multiplied by three to represent a 90-day or quarterly billing period.
Multi-family residential customer
Sanitary sewer: $13.54 per 100 cubic feet of water use
Stormwater service unit: $6.310 per service unit per 30 days
Stormwater billable area: $14.013 per 1,000 square feet of stormwater billable per 30 days
The example below is for a multi-family residential customer who used 350 ccf (one ccf equals 100 cubic feet), has 35 dwelling units, has 25,000 square feet of stormwater billable area, and is billed quarterly.
| Charge | Calculation | Total |
|---|---|---|
| Sanitary sewer | $13.54 x 350ccf | $4,739.00 |
| *Stormwater service unit | 35 x 0.65 = 22.75 service units (22.75 x $6.310) x 3 | $430.66 |
| **Stormwater billable area | ($14.013 x 25) x 3 | $1,050.98 |
| Total sewer and stormwater charges | $6,220.63 |
*The stormwater service unit rate is per 30 days. In the calculation above, the number of dwelling units is first multiplied by 0.65 to get the number of service units. The number of service units is multiplied by the stormwater service unit rate and then by three to represent a 90-day or quarterly billing period.
** The stormwater billable area rate is per 1,000 square feet per 30 days. In the calculation above, the rate is first multiplied by 25 (25,000 square feet) and then multiplied by three to represent a 90-day or quarterly billing period
Non-residential customer
Sanitary Sewer: $14.00 per 100 cubic feet of water use
Stormwater service unit: $6.310 per service unit per 30 days
Stormwater billable area: $14.300 per 1,000 square feet of stormwater billable per 30 days
The example below is for a commercial customer who used 250 ccf (one ccf equals 100 cubic feet) and has 40,000 square feet of stormwater billable area.
| Charge | Calculation | Total |
|---|---|---|
| Sanitary sewer | $14.00 x 250ccf | $3,500 |
| *Stormwater service unit | 40,000 ÷ 2,400 = 16.67 service units 16.67 x $6.310 | $105.19 |
| **Stormwater billable area | $14.300 x 40 | $572 |
| Total sewer and stormwater charges | $4,177.19 |
*The stormwater service unit rate for commercial customers is calculated using the square footage of impervious area, not the number of dwelling units like residential customers. In the calculation above, 40,000 square feet is first divided by 2,400 square feet to get the number of service units. The number of service units is then multiplied by the stormwater service unit rate.
** The stormwater billable area rate is per 1,000 square feet. In the calculation above, the stormwater billable area rate is multiplied by 40 (40,000 square feet).
Portland Harbor Superfund Charge
The Portland Harbor Superfund charge goes towards the clean-up of Portland Harbor.
- $0.04 per 100 cubic feet of water use
- $0.19 per 1,000 square feet of impervious area per 30 days
Clean River Rewards discount
Clean River Rewards offers up to a 35 percent discount on your stormwater charges. Customers who safely manage some or all of their property's stormwater runoff on their properties can register for a discount on their stormwater charges.
Learn more and register for Clean River Rewards
All rates, charges, and fees
If you are looking for Environmental Services’ complete list of rates, charges, and fees, view Environmental Services' full list of rates and charges.
Full List of Environmental Services Rates and Charges
Managed floodplain customers
About 1,500 Environmental Services customers are located within Portland’s managed floodplains (formerly known as Drainage Districts), which manage flood control and the Columbia River levee system. Historically, these customers have paid about 35 percent less for stormwater services due to longstanding agreements.
To align with the actual cost of providing services, Environmental Services is phasing in rate increases until customers inside managed floodplains are paying the full cost of service rate as all other customers pay. The full phase-in will occur on July 1, 2026.
Frequently asked questions
How do we determine our rates?
Environmental Services undergoes a financial planning process every year to determine the sanitary sewer and stormwater rates required to fund operations for the upcoming fiscal year. The final step is the Sewer and Stormwater System Rate Study.
Every dollar of your sanitary sewer and stormwater rates and charges helps fund the following:
- $0.35 - Operation and Maintenance: Ongoing costs for the operations and maintenance of the pipes, ditches, culverts, sumps, maintenance holes, pollution control facilities, wastewater treatment facilities, and more.
- $0.34 - Capital Improvement Program: Capital Improvement Program projects repair or replace aging pipes and help protect people, property, and the environment.
- $0.22 - Debt Service: Debt service payments are payments for previously completed projects, such as the Big Pipe Project.
- $0.09 - Other Expenditures: Other expenditures necessary for service functions, including payments to the general fund, pension obligation bond payments, and the Portland Harbor Superfund.
Why do sewer, stormwater, and water rates increase?
Every year, Portland City Council votes on an annual rate increase. This vote sets rates for Environmental Services and the Portland Water Bureau. The annual rate increases allow the bureaus to raise the additional funding needed to cover the rising costs of providing services.
These increases ensure that the bureaus can operate, maintain, and improve the systems that Portlanders rely on every hour of every day.
Why are single-family residential properties placed in stormwater billable area categories?
In the past, Environmental Services billed all houses a flat rate for stormwater. This meant that homes with large amounts of stormwater billable area were billed the same as homes with small amounts of stormwater billable area. Environmental Services is retiring the flat rate and creating a new structure for billing homes for stormwater instead.
Under the new rate structure, residential properties will be divided into one of three categories based on the amount of stormwater billable area on that property. Properties with less stormwater billable area will be billed less, and properties with larger amounts of stormwater billable area will be billed more. Most residential customers will remain in the standard category or be placed in the category for properties with smaller amounts of stormwater billable area.
How can I calculate my stormwater billable area?
Using a tape measure, find the length and width in feet of your property’s stormwater billable area. You can also use the Stormwater Billable Area Measurement Tool.
Then, add up all of your stormwater billable area features to get your total stormwater billable area.
- Main house: 35 ft x 35 ft = 1,275 sq ft (1,225 sq ft + 50 sq ft of entry)
- Detached garage/carport: 25 ft x 16 ft = 400 sq ft
- Shed: 15 ft x 10 ft = 150 sq ft
- Driveway: 30 ft x 10 ft = 300 sq ft
- Walkways (flagstones): 48 ft x 1 ft = 48 sq ft
- Walkways (paved): 41 ft x 2 ft = 82 sq ft
- Circular patio: π x 102 ft = 314 sq ft
Total measured stormwater billable area = 2,569 sq ft
This worksheet can also be used to help measure your property’s stormwater billable area.
I think my stormwater billable area is inaccurate. What can I do?
City of Portland water, sewer, and stormwater customers for single-family residences are assigned either a small, standard, or large stormwater billable area category. If you believe your assigned category should be different, learn how to request a change to your category.
Guide to requesting a change to your stormwater billable area
I live in a floating home, why am I still being charged for stormwater?
For commercial properties (including floating home communities and other properties with structures over water), stormwater billable area is used to calculate stormwater service units. Because overwater structures are not included in the stormwater billable area calculations for any properties, they are not charged for service units on the portion of the property overwater. Portions of the property that are over land, such as parking lots, are considered stormwater billable area and are factored into stormwater charges.