NASHVILLE — A Tennessee Regulatory Authority official has given the state’s consumer advocate, Chattanooga and local manufacturers more time to develop expert testimony they believe can show Tennessee-American Water Co.’s proposed 20.58 percent rate increase is “too high.”

In a status conference last week, Richard Collier, the regulatory authority’s hearing officer, extended until Friday the deadline for state, city and Chattanooga Manufacturers Association attorneys to submit pre-filed testimony from their experts. The previous deadline was Monday.

The move came as city, state and industry representatives, who had appealed Mr. Collier’s previous deadline, prepared to go before the regulatory authority’s directors and argue that procedural foot-dragging by Tennessee-American shouldn’t be allowed to penalize Chattanooga consumers.

“The consumer rates set in this proceeding will affect the pocketbooks of Chattanoogans for a long period of time,” attorneys had argued in their appeal. “It is therefore better to set these rates correctly rather than quickly.”

Citing their belief they can demonstrate the increase request is too much, the attorneys argued that “the only way the Intervenors (state, city, manufacturers) can adequately present it is to complete their work and prepare their pre-filed testimony.”

Attorney Rick Hitchcock, who is helping to represent Chattanooga, said he is pleased by the latest ruling.

“There has been a series of procedural delays that have occurred in this case, and that has prevented us from getting information from Tennessee-American to prepare the substantive testimony,” Mr. Hitchcock said.

In an e-mail statement, Tennessee-American spokeswoman Kim Dalton said, “This rate increase seeks to recover the investment that Tennessee American Water has made ($27 million) to provide its customers with reliable, high-quality water service.”

Ms. Dalton noted “all the parties have agreed to a modification to the procedural schedule so the case can be completed within the statutory six month time period.”

In an earlier filing, water company attorneys had objected to extending the deadline, arguing it would cause further delay in the case.

They accused the city, state and manufacturers of having “completely disregarded” discovery limitations in the case and noted the company has exercised “incredible effort” to accommodate requests “while simultaneously seeking to ensure that appropriate safeguards were afforded the most sensitive material requested.”

The TRA voted 2-1 last year to approve a 12.3 percent rate increase for Tennessee-American.

This year’s rate case is expected to be heard by directors Eddie Roberson, Tre’ Hargett and Mary Freeman.

Mr. Roberson was not involved in last year’s case, and Mr. Hargett and Ms. Freeman are new to the TRA.