The consortium asked for the letters so that it can make more accurate estimates about the cost of water. Cities can buy a minimum 1 million gallons per day capacity and agree to use 20 percent of that in order to be connected to the pipelines. The annual cost would be about $450,000.
But Lancaster has only agreed to buy 500,000 gallons a day.
Mayor Pro Tem Donna Powell said Monday night that the city will consider joining the consortium "as insurance," but that the costs involved will have to be carefully studied.
"It's not really that we need the water right now," she said. "We're thinking about this as insurance for the future."
The price for Lancaster would be $200,000, but its smaller purchase amount will have to be reviewed by the consortium, said Hassall.
Danville commissioners agreed to sign the letter, but have delayed passage of a resolution because the first draft didn't have the words "non binding" in it.
Danville faces a decision, because of tougher federal drinking water standards, on how to upgrade its water treatment plant. Commissioners will decide in coming months how big of a plant to build, and whether it will extend its customer base in Mercer, Lincoln and Casey or to the commission's larger network that surrounds Lexington.
The consortium members have decided to build a treatment plant north of Frankfort, but Hassall said nothing would be definite until construction begins.
Danville draws its raw water from Herrington Lake, and has to secure permission from Kentucky Utilities before it can sell water outside Boyle County. KU and the city have begun negotiations.
According to city consultants, if Danville built a 15 mgd plant and sold its extra water, then the cost would be $1.55 per 1,000 gallons.
Danville and its area customers, like Hustonville, now use 4.5 mgd, and pay $1.69 per 1,000 gallons. But the city must upgrade its plant.
If the city just made the necessary changes to its existing plant, the cost would be $1.92 per 1,000 gallons. That plant's maximum capacity is about 7 mgd. If Danville were to buy 7 mgd capacity from the commission, it would cost $4.09 per 1,000 gallons.
Staff Writer James Logan contributed to this story.