More than six months ago, the board of directors of Loudoun Water requested that Loudoun County officials decide on a long-term solution to ongoing water quality complaints in the Raspberry Falls community by the end of this month.

With the arrival of that deadline — and no decision by Leesburg town officials or Loudoun supervisors — Loudoun Water announced this week that it is still working with local officials to determine the appropriate response to longtime concerns about the quality of the water supply in the subdivision. A final decision could come in mid-June, said Mike McGill, spokesman for Loudoun Water.

Residents of Raspberry Falls, a community just north of Leesburg, have complained for years that their water supply is particularly vulnerable to contamination. The subdivision is on rocky terrain that doesn’t filter possible contaminants from the water supply as effectively as soil or sand, allowing surface water to seep down through channels in the stone to the groundwater below.

Some homeowners have pointed to anecdotal accounts of illnesses as evidence that people have been sickened by the water, although officials with the Virginia Department of Health have found no conclusive evidence of illnesses caused by the community’s water supply.

The residents’ concerns mounted after the Department of Health found in November 2010 that tainted surface water had drained into the untreated groundwater feeding one of the community’s two wells. The affected well was immediately shut down, and the board of Loudoun Water voted to study possible long-term solutions to address the issue.

After months of subsequent research, Loudoun Water’s board of directors passed a resolution Nov. 10 saying two potential solutions should be considered to address the community’s water problems: an advanced water-treatment method or the construction of a pipeline extension from Leesburg to Raspberry Falls.

The pipeline is the more complicated and costly choice. Because the community is part of a rural zoning area, a pipeline extension from Leesburg would first require that the Board of Supervisors vote to rezone the area in the county’s general plan.

As part of its resolution, Loudoun Water requested that local officials decide whether to pursue the pipeline option by the end of May. If they did not, Loudoun Water said, it would proceed with installing a membrane filtration system at Raspberry Falls.

“This request was made based on Loudoun Water’s belief in the need to act upon a long-term solution, combined with its ability to move forward immediately with the work on the treatment option without the need for legislative action,” the company said in a statement Tuesday.

The membrane filtration system, which would take about two years to build, is the option favored by Loudoun Water.

Despite the deadline, McGill said, it is not definite that Loudoun Water will proceed with the membrane filtration system over the pipeline. The matter will probably be discussed at a board meeting next month, he said, although it’s possible that the discussion could be delayed.

Loudoun Water’s statement noted that company officials have been engaged in discussions with town and county officials since November.

“Following the passage of the deadline of their May request, Loudoun Water’s Board of Directors will review the results of these discussions and the actions made by the key stakeholders to determine the proper path forward,” the statement said.