A plan by the city of Tampa to convert highly treated wastewater into drinking water would benefit the economy and the environment of the entire Tampa Bay region. That’s why it’s critical to get buy-in across the three-county area, and that starts with fostering a comfort level with the project that’s based on collaboration and trust. Officials took a positive step in that direction Monday, and they should build on that dialogue in the coming weeks.Tampa provides 4 million to 6 million gallons of treated wastewater every day to reclaimed water customers in the South Tampa area. But its treatment plant discharges a far greater amount, about 60 million gallons daily, into Tampa Bay. Under a concept in the planning stages for several years, the city would redirect about 50 million gallons a day from the treatment plant into the aquifer, where it would naturally filtrate. Then the water would be pumped back up, with roughly half going to the city’s water treatment plant and the other half to the Hillsborough River reservoir, where Tampa Bay Water, the three-county regional utility, could use it to meet the bay area’s drinking needs. By that point, the wastewater would have been treated at least three times.Last month, however, the Tampa Bay Water board — whose members include Pinellas, Hillsborough and Pasco counties, and the cities of St. Petersburg, Tampa and New Port Richey — voted to delay approval of the project. St. Petersburg, in particular, is concerned that a Tampa-driven project could undermine the agency’s regional mission. St. Petersburg City Council member Darden Rice also told the Tampa Bay Times editorial board this month that some of her financial and environmental concerns have not been addressed.The effort took a step forward Monday when Tampa sent an e-mail to agency board members expressly confronting some key concerns. The city said it would not pursue so-called “nutrient credits” to effectively sell the discharge reductions in the bay to another polluter. Tampa defended its $350 million cost projection as a “conservative” estimate, and also said it was continuing to work on any permitting issues.Having these assurances in writing should give the board greater confidence. A consultant’s report issued in August found that the Tampa Augmentation Project “is a feasible, cost-effective water supply alternative for the city of Tampa and the region as a whole.” The plan would meet Tampa’s long-term water needs and free up at least 20 million gallons a day for the region. The plan could save Tampa Bay Water up to $35 million for water supply projects that would not be needed. And by redirecting these massive discharges, the project would remove huge amounts of nutrients now flowing from Tampa’s treatment plant into the bay — about 885 pounds of nitrogen and 1,069 pounds of phosphorus every day, an 80 percent reduction. “The nutrient reductions that can be achieved through TAP are substantial,” the consultant’s report in August found. Redirecting water to the reservoir would improve the health of the bay and the river alike.Rice said Tuesday she was pleased that Tampa agreed in writing not to pursue nutrient credits, which she called significant and relevant new information. Rice also suggested the reasonable step of codifying Tampa’s pledge into any operating agreement. The board is scheduled to hold a workshop on the project next month, and Tampa is expected to bring the plan to another vote in February.Resolving any concerns in a timely manner is essential for Tampa’s project to compete for the next round of state funding. This is an opportunity to put a wasted resource to precious use for the good of the entire region.