Impervious Area FAQs

In January 2026, DC Water paused the rollout of new Clean Rivers Impervious Area Charge (CRIAC) Equivalent Residential Unit (ERU) measurements in response to concerns about bill impacts and the clarity of our communications. Annual CRIAC rate adjustments will continue, but changes to ERU measurements will not begin before Fiscal Year 2029 (October 1, 2028).

This pause in updating ERU measurements will allow us to ensure the process is fair, accurate, and transparent for everyone. These FAQs for the Pause in CRIAC Measurement explain the reasons for the pause, its effect on billing, and what steps DC Water is taking to address community feedback. 

Below you will also find general FAQs about the Impervious Area Charge. 

1. What is a Clean Rivers Impervious Area Charge (CRIAC)?

An impervious surface is a man-made surface that cannot be easily penetrated by water, such as rooftops, driveways, patios, tennis courts, swimming pools, parking lots, and other paved or covered areas (regardless of materials used).

Impervious surface areas are a major contributor to rainwater runoff entering the District's sewer system and pollution entering area waterways. The CRIAC is based upon the amount of impervious surface on your property.

2. Why is the CRIAC necessary?

The charge is necessary to recover the costs of the $3.27 billion federally mandated Clean Rivers Project (linked). The plan will reduce the discharge of excess combined sewer overflows into local waterways from DC Water's combined sewer system.

3. Why did DC Water decide to defray the costs of the Clean Rivers Project in this manner?

The DC Water Board of Directors determined that the CRIAC is a more equitable way to recover the costs of the Clean Rivers Project than the volumetric charge (for water used), because the CRIAC is based on a property's contribution to rainwater runoff.

4. How is the amount of the charge determined?

The charge is based on an Equivalent Residential Unit (ERU). An ERU is a measure of the amount of impervious surface area in a single-family residential property in square feet. All nonresidential customers are assessed ERUs based on the total amount of impervious surface on each lot. The approved monthly ERU values for FY 2025 and FY 2026 are $21.23 and $24.23 respectively.

Residential Customers: Beginning in FY 2011, all residential customers were assessed ERUs based upon the amount of impervious surface on their property and the following six-tier rate structure:

  Former FY 2025
(Effective 10/1/2024)
Current FY 2026
(Effective 10/1/2025)
Area (Square Feet) ERU ERU Rate Monthly Cost ERU Rate Monthly Cost
100-699 0.6 $21.23 $12.74 $24.23 $14.54
700-2,099 1.0 $21.23 $21.23 $24.23 $21.86
2,100-3,099 2.4 $21.23 $50.95 $24.23 $58.15
3,100-7,099 3.8 $21.23 $80.67 $24.23 $92.07
7,100-11,099 8.6 $21.23 $182.58 $24.23 $208.38
11,100 and more 13.5 $21.23 $286.61 $24.23 $327.11

All nonresidential customers are assessed ERUs based on the total amount of impervious surface on each lot.

5. Why did DC Water develop a Tiered Rate structure for residential customers?

The tiers were developed in order to bill residential customers more equitably, based on the size of their properties.

6. If I do not agree with the square footage for which DC Water is billing me, how can I appeal?

You may follow the bill dispute process (link) located on the back of your bill.

7. How was the square footage determined for my property?

Square footage is measured using the geographical information system data from DC GIS and Office of the Surveyor.

8. Is there a discount for residents who implement measures to manage and/or reduce wet weather runoff?

To apply for the IAC Incentive Program, and receive more information on the District Department of Energy & Environment's Riversmart Rewards Program, visit their website here.

Upcoming Meeting

Board of Directors Meeting

April 24, 2023

Monday 9:00 AM

Announcement

Picture of new bike pedestrian path and traffic detour
New Path for Capital Crescent Trail Opens at Georgetown Waterfront Park

DC CLEAN RIVERS – POTOMAC RIVER TUNNEL PROJECT
If you bike, drive, or walk through Georgetown, we’ve got changes starting this week around the Potomac River Tunnel construction on Water Street NW. The Capital Crescent Trail has a new temporary detour through Georgetown Waterfront Park, open now for cyclists between 33rd and Potomac streets NW.

Latest Blog Post
A helicopter lowers a drill rig to workers on the Potomac River.
DC Water begins drilling in Potomac River to explore options to rehab underwater sewer line
When one of your major sewer lines runs through the Potomac River, a backhoe and trencher won't do. That's why we've got helicopters carrying a 14-ton drill and workers suspended midair over the Potomac.
Upcoming Meeting
Date
January 20, 2026
Tuesday, 2:00 PM

Upcoming Events

Customer Service Center Announcement

Payment Plan Incentive: provides a credit back of 40% of the last 3 payments made and in the new fiscal year 50% will be credited. Eligible participants are residential customers who have had an outstanding balance for 60 days or greater and with an outstanding balance of $500 or more.