Water & Sewer Rate Study and Indirect Cost Study

The Town of Vienna is seeking a consultant to perform a water and sewer rate study and an indirect cost study to properly allocate costs between the water and sewer and general funds.

Located in Northern Virginia and approximately 14 miles from Washington D.C., the Town of Vienna is an incorporated town within Fairfax County—adjacent to Tysons Corner (Northeast), Oakton and Fairfax City (Southwest), Merrifield/Mosaic District (Southeast) and Reston (Northwest). The Town is 4.4 square miles and home to approximately 17,088 residents.

Vienna is primarily a residential community with at least 71 percent of the land developed for residential purposes, excluding rights-of-way. The Town has approximately 3.5 million square feet of commercial and industrial space—60 percent is used for professional office space, 30 percent of the space is used for retail, and the remaining 10 percent is used for industrial purposes. Vienna is also home to a diverse business base serving independent retailers and even the nation’s largest credit union, Navy Federal Credit Union.

The Town is fully built out. The commercial corridor has a few mixed-use projects under construction described below and there is significant residential redevelopment. The Town’s 2020 Census population was 16,473. There are approximately 5,500 residential units, primarily single-family homes and 430 commercial properties.

Water and Sewer System

The Town of Vienna operates a Water and Sewer system and owns the infrastructure but does not treat water or wastewater. The Town purchases its water solely from Fairfax Water under a long-term agreement. There is a fixed capacity charge and a consumption charge that increases over time.

Approximately 50% of the Town’s wastewater is treated by DC WASA and 50% by Fairfax County, VA. The agreements are also long term. DC WASA builds its capital cost recovery into the rate charged per MGD. Fairfax County bills both operating and capital costs semi-annually. The Town pays for water purchases, DC WASA sewer fees and Fairfax sewer operating costs on a pay-as-you -go basis but uses bond funds financed by water and sewer fees to pay Fairfax sewer capital improvements every other year. The infrastructure is also supplemented by capital donated from developers, a small portion of total system costs.

The Town’s infrastructure consists of 137miles of water lines and 95 miles of sewer lines. A valuation and condition assessment study was performed in the summer of 2025.

The Fund has approximately 21.5 employees. The Water and Sewer system serves about 9,500 service connections, 6,000 in town and 3,500 out of Town. The sewer system serves approximately 6,300 connections in the service area. The remainder of the accounts are served by Vienna water and Fairfax County sewer. Approximately 80% of the customers are residential. Block rates have been in effect since 2014. Current rates are based on a water and sewer rate study performed in 2023, and an indirect cost study was last performed in the same year.

The rates developed in the study as adjusted by actual consumption patterns are being used as the basis for the FY 2025-26 budget year, which began on July 1, 2025. The rates and indirect costs developed in this RFP need to be available for use in the FY 2026-27 budget preparation, which begins in January 2026.

Fees charged for new water and sewer system connection have been linked to Fairfax County Water Authority for water and Fairfax County for sewer. This needs to be taken into account in the calculation of rates and fees.

Vienna’s Residential Redevelopment

The Town has approximately 5,800 residential parcels, of which 80 percent are single-family detached homes. There are currently 671 (11%) apartment and condominium units and 507 (9%) townhouses, duplexes and other attached housing in Vienna.

More than 50% of the existing Town’s housing units were built before 1970, with some houses dating to the 1800s. Each subsequent decade since 1970 has seen the development of at least 200 units, with peaks occurring in the 1970s and in the two decades since 2000. Due to Vienna’s location in the national capital region and within the jobs-rich Fairfax County, the demand for housing in the Town has almost always been very strong. The last 15 years has very large amount of residential rebuilding, in which smaller and lower-priced homes are torn down and replaced by larger and more-expensive homes. For the decade beginning in 2010, there was an average of more than 100 residential rebuilds per year. Though this volume has decreased in recent years, there has still been 75-80 new housing units per year since 2022, including both rebuilds and new units. A new development that was recently completed was a 24-unit condominium project, consisting of 12 vertical duplex buildings. All units have been sold. In 2023, a 12-unit duplex project, in a “cottage courts” format; and all units were successfully sold even before completion. Also completed in 2023 was an 82-unit facility for seniors, developed by Sunrise Assisted Living.

Many single-family housing rebuilds are currently under review. A new project currently in the review process involves development of a mixed-use building on Maple Avenue East, with more than 40 multifamily units above commercial space.

Previously Approved Projects Involving Water and Sewer Service

Projects that have been approved that are either not yet completed or started include: 1) A mixed-use project along Maple Avenue East, at the intersection with Nutley Street, that is approved for 151 apartments and up to 20,000 square feet of commercial space; 2) the mixed-use Vienna Market project at the intersection of Maple Avenue East and Pleasant Street, whose 44 townhouses are completed and occupied, but with the retail component not yet leased; and 3) the renovation of the Patrick Henry Library which includes a new multi-level garage facility.