The Ames water plant is about to run dry.

“Right now, we are running at about 82 percent of our 12-million-gallon-per-day capacity,” said John Dunn, director of water and pollution control for the city of Ames.

The plant calculates demand using a rolling three-day average of water dispensed, which helps compensate for single high-demand days. Last summer, the season with the highest average water demand, peak use was 9.81 million gallons in a day.

“For water plants across the country, 85 percent is usually the magic number for needing to plan an expansion,” Dunn said.

At the Capital Improvement Plan reading in front of the City Council on Tuesday, Dunn and Christina Murphy, assistant director of water and pollution control, showed a chart detailing an upward trend in water demand over the last five years.

“If demand continues to increase at the rate it is now, the plant will be at 100 percent capacity in 2012,” Dunn said.

At the meeting, Dunn and Murphy asked for $29.25 million for a new plant, instead of just expanding.

“Our current facility was built in the late ’20s, so it is 80 years old,” Murphy said. “It’s not to the point where it will crumble overnight, but we are seeing serious deterioration.”

The figure of $29.25 million is a rough estimate judged by the water department.

“We based that estimate off of recent plant construction in Boone and Iowa City,” Murphy said. “It roughly comes down to about $2 million for every million gallons per day.”

Currently, the plant is gathering information that would be useful to consultants who will be brought in to determine whether the current location will be feasible for a new plant.

“There are some substations behind the plant, so there are a few space concerns,” Murphy said.

Another area of concern is the timetable for the new plant.

“Five years is a pretty aggressive build schedule for a new plant,” Dunn said. “We would feel more comfortable with a little more time.”

To get that extra time, the plant will need to reduce the peak demand. To that end, Dunn and Murphy urge people to be smart about how they use water.

“In Ames, the average person uses 50 gallons a day. We’re not asking for radical life changes here,” Dunn said. “For example, the average shower head uses a gallon a minute. If a person cuts down their shower by five minutes, they just cut down their water spent by 10 percent.”

Dunn also said the main thing that drives summer water usage is outdoor uses, such as sprinklers.

“Try and make sure that the sprinkler hits the lawn and not the street. Use auto-shutoff nozzles,” he said.

Another plan in the works to slow peak usage is to implement a program that calculates an average amount per day for a house based on the size of the water meter and class the building is in, such as residential or industrial.

“These buildings would get an allotted amount. In summer, if they go over, their rates go up,” Murphy said. “There would be a little bit of flexibility, but we’re researching that idea now.”

Dunn said that, regardless of conservation plans, water rates would go up to help cover costs.

“The overall plant revenue is around $7.5 million, so this is a big expense. To match that, the rate increase will be not insignificant,” Dunn said.