Stormwater Fee FAQ

Read on for answers to common questions about the stormwater fee, impervious surface area, and the credit program. 

Frequently Asked Questions

What does the new stormwater fee fund?

Revenues generated from the stormwater fee directly fund costs related to stormwater management within the city of Pittsburgh. These costs include the construction of new stormwater projects, including green infrastructure, the operation and maintenance of our stormwater system such as the cleaning of catch basins and maintaining rain gardens, and meeting regulatory requirements to improve water quality. These services benefit the community by managing flooding, basement backups, and pollution. 

How is the stormwater fee calculated?

The stormwater fee is based on a property’s hard or impervious surfaces. In Pittsburgh, the average amount of impervious surface on a residential property is approximately 1,650 square feet. This is equal to one equivalent residential unit (ERU) of impervious surface, which is the unit of measure for calculating the stormwater fee and is accepted as the industry standard for determining a stormwater fee. The stormwater fee is applied to all residential and non-residential properties in Pittsburgh in the following way:


Stormwater Monthly Fees ERUs 2024

Residential Tier 1:
(>= 400 sf to < 1,015 sf)

0.5 $5.03
*Residential Tier 2:
(>= 1,015 sf to < 2,710 sf)
1 $10.06
Residential Tier 3:
(>= 2,710 sf)
2 $20.12
Non-residential Per ERU $10.06
*70% of all Pittsburgh homeowners fall into Residential Tier 2.

What is impervious area and why is it important?

Aerial image of a property showing impervious area.

Impervious area is any manmade surface resulting from parcel improvements which prevents or limits the infiltration of water into the ground, including:

  • roofs
  • private streets
  • driveways
  • concrete pads
  • structures
  • mobile homes
  • private sidewalks/walkways
  • parking lots
  • patios and decks
  • athletic facilities and artificial turf
  • pools (above ground and in-ground)
  • compacted earth or clay, gravel that is installed and maintained for vehicle travel or parking*
  • trails (paved or unpaved)
  • retaining walls
  • foundation walls, foundations, and rubble from razed buildings

These hard surfaces carry stormwater runoff to the sewer system. Impervious area-based rate structures are the industry standard for determining a stormwater fee. Approximately, 92% of stormwater utilities are based on impervious surface.

Impervious area is shaded in blue on the aerial image of a property on the right. 


* PWSA’s default position is that gravel is classified as impervious.  However, PWSA may review customer appeals on a case-by-case basis for situations where a gravel driveway or lot was specifically designed and installed for high permeability and stormwater management.  PWSA requests invoices, photos, etc. that document the materials/performance, and reserves the right to inspect the stormwater-friendly gravel driveway or lot.   


Gravel: Gravel driveways or lots designed and installed for stormwater management (see above).

Mulch: For the purpose of the stormwater fee, PWSA considers wood mulch as a permeable surface, provided that it is spread on non-compacted earth and is not stored in a pile. The substrate should be a material that would be considered as pervious if it were the top layer.

Razed Buildings: If inside foundation walls are vegetated, which may occur from a prolonged vacancy that weeds and other vegetation are growing in its rooms, this area is considered pervious.  If the foundation is compacted or constructed of concrete and is not vegetated, it is considered impervious.

Are stormwater fees common in PA?

Yes, stormwater fees are common in Pennsylvania and nationwide.  In Pennsylvania, almost 60 communities have implemented stormwater fees. Fees are in place in Allentown, Lycoming County, Philadelphia, Harrisburg, and Lancaster, and closer to Pittsburgh in Baldwin Borough, Coraopolis, Cranberry Township, Fox Chapel, Hampton Township, Moon Township, North Fayette Township, Mount Lebanon, O’Hara Township, Monroeville, Dormont, Plum Borough, and Whitehall Borough. (Western Kentucky University Stormwater Utility Survey, 2021)

Are there ways I can reduce my fee?

Yes, PWSA ratepayers can reduce their fee by receiving credits, reducing impervious surface, or enrolling in the bill discount program for low-income customers.

Credits are awarded to customers that have stormwater control measures in place which capture and detain a defined amount of runoff, to reduce the amount entering the sewer system. Requirements differ for residential and nonresidential customers. PWSA reviews and approves the application before awarding a credit.  For more information, please visit

The Bill Discount Program is in place for residential customers who are at or below 150% of the Federal Poverty Level. For more information, please visit

What types of stormwater management solutions are eligible for a stormwater fee credit?

To receive a stormwater credit, property owners must manage a required amount of stormwater on their property as outlined in our Stormwater Fee Credit Manual.  

Rain gardens are an accepted method to manage stormwater and are commonly used on residential and non-residential properties. With proper planning, they are a cost-effective, and are generally easy to install and maintain. Since they use vegetation and soils to filter pollutants and absorb the rain, water is treated as a resource rather than running off into the street and our sewer system.

Other solutions that PWSA considers as eligible for a stormwater credit are listed in Worksheet 5 of the Pennsylvania Stormwater Best Management Practices Manual. These also include dry wells and green roofs, which require more planning and are more expensive to install and maintain.

Permeable pavement or pavers when designed with a sub-base to allow for stormwater infiltration and management, are not eligible for a stormwater credit, but can be deducted from the impervious area calculated for your parcel, which can help to reduce your overall stormwater fee.  

Please review our Stormwater Fee Credit Manual and application for more information to determine your parcel’s impervious area and the amount of runoff to control to earn the stormwater credit.

What if I believe my impervious area is measured incorrectly?

Customers who disagree with their fee calculation can submit a dispute through customer service, after which PWSA will launch an investigation and report the results back to the customer. This investigation may involve a PWSA official visiting the property to assess impervious area.  For appeals processed in favor of the customer, the authority will issue a corrected bill with a new due date. Any amounts received by the authority in excess of the amount due will be refunded to the customer. If the dispute is denied, we will explain the decision and if you are still dissatisfied will provide additional steps you can take.

All my downspouts discharge into my yard rather than the sewer, why do I have to pay a stormwater fee?

All properties with impervious area generate stormwater runoff. PWSA uses the amount of impervious surface on a parcel as the basis for our stormwater fee. The specifics of how different properties connect to, drain to, or benefit from infrastructure can vary but all will be assessed a fee to cover stormwater costs. The fee helps to cover system-wide stormwater management costs including maintenance of existing infrastructure, construction of new stormwater systems, and meeting state water quality requirements. By basing the fee on impervious surface, all properties contribute their fair share in helping to manage stormwater in Pittsburgh. 

Customers who have disconnected their downspouts can redirect them to a stormwater control measure to manage ¾ of an inch of runoff from their property’s total impervious surface to earn a stormwater credit. Downspouts that have been disconnected and are directing stormwater runoff to a yard are not eligible for a stormwater credit. Downspouts must be directed to a stormwater control measure like a rain garden or underground storage system to be considered for a credit. Please visit to download the Stormwater Fee Credit Manual and application form.

Can I get a stormwater fee credit for my rain barrel?

PWSA offers residential customers a one-time $40 credit for an installed rain barrel of at least 50 gallons that captures and detains roof runoff on their property.  One rain barrel per parcel will be allowed a credit. For more information and to apply, please visit

Will there be rate increases?

PWSA’s rates are determined by the Pennsylvania Public Utility Commission (PUC). Prior to any rate increase going into effect, we will file a rate request with the PUC. This is an extensive process, which provides opportunities for public input and requires PWSA to notify all customers when the rate request is filed.

The PUC approved the stormwater fee in 2021. (see How is the stormwater fee calculated? in this FAQ).

What if the data PWSA uses to determine the stormwater fee is updated?

Your stormwater fee calculation is based on aerial imagery and parcel boundaries. Newer imagery and updated parcel boundaries will become available over time, but PWSA will not change the impervious area on your property unless things have changed on the ground due to construction, demolition, or other site modifications, or to correct a mistake.

How will the stormwater tariff impact other municipalities that buy water from PWSA, but whose residents are not direct ratepayers?

PWSA’s stormwater fee will only apply to customers within the city of Pittsburgh who receive wastewater services. It applies to all Pittsburgh property owners.