The water agency for Prince George's and Montgomery counties predicts needing a 19 percent increase in its construction budget to pay for improvements to its aging system over the next six years -- probably meaning more rate increases for residents in the coming years.

In the next fiscal year alone, the Washington Suburban Sanitary Commission anticipates spending $642.3 million on construction projects, $78.2 million more than budgeted for the current year.

Between fiscal 2014 and 2019, the WSSC expects costs of roughly $2.1 billion, $399.2 million more than for the period of six fiscal years that began July 1. Of these costs, 70 percent are for improvements to existing water and sewer systems, rather than changes needed to accommodate an increase in demand or new environmental regulations.

The WSSC's funding requests
  Est. total Expenses through fiscal 2012 Est. expenses fiscal 2013 Fiscal '14-'19 Fiscal '14 request
Montgomery County water projects $40m $5.6m $7.1m $27.3m $11m
Prince George's County water projects $186.3m $28.8m $9.8m $137.9m $37.1m
Bicounty water projects $723.6m $260.1m $93m $370.5m $103.3m
Total water projects $949.8m $294.5m $109.8m $535.7m $151.4m
Montgomery County sewer projects $70.1m $20.7m $24.6m $24.7m $15.7m
Prince George's County sewer projects $435.4m $55.8m $88.2m $291.4m $107.6m
Bicounty sewer projects $2.3b $787.5m $296.7m $1.2b $367.6m
Total sewer projects $2.8b $863.9m $409.6m $1.5b $490.8m
Total WSSC construction $3.8b $1.2b $519.4m $2.1b $642.3m

The improvements are desperately needed, according to WSSC spokesman Jim Neustadt. About a quarter of the WSSC's 5,551 miles of water main are at least 50 years old, he said. By fiscal 2015, the agency hopes to begin replacing 55 miles of water main a year, at a cost of about $1.4 million per mile of pipeline.

In fiscal 2011, the last year for which complete data is available, there were 34.7 water main breaks for every 100 miles of water main, and the agency expects roughly 34 breaks for every 100 miles in the current fiscal year.

To cover the costs, the agency is considering recommendations by a panel of officials from both counties and the agency itself to charge residents an extra rate based on how much water they use. Customers would pay that rate in addition to current usage charges.

"The goal is moderate ... future rate increases to ease the burden on customers by lessening what could be very steep increases in rates," Neustadt said.

Rates have been raised the last five years, including fiscal 2013.

The bicounty agency proposes investing revenue earned from ratepayers to cover $469.3 million in fiscal 2014, and $1.7 billion over the whole six years. The rest would come from federal and state grants, developers' fees and local government contributions.

Though the agency proposes to reduce the burden on ratepayers by investing funds over a longer period of time, residents could still be facing moderate rate increases for years to come, according to Raftelis Financial Consultants, commissioned by the WSSC to study financing scenarios. "Even in the most advantageous financing scenarios, rate revenue requirements are expected to increased by $200 million [between fiscal 2013 and 2018]."

The commission has not made any decisions on whether to implement the new rate structure. The WSSC plans to hold public hearings this month.