HOUSTON (AP) - A review of Houston water records shows the city lost more than 18 billion gallons of water potentially worth tens of millions of dollars at the height of this summer's punishing drought.

A Houston Chronicle examination of records shows leaking and broken pipes sent more than 9 billion gallons of water down the drain in September in October alone when city officials were urging residents to conserve and had to tap into emergency supplies.

"Water is a valuable resource, and we're blowing it right and left," Katie Molina, general manager of the Citizens' Environmental Coalition in Houston, said. "We have to ask why we have so many leaks. Is it all drought-related, or did we let our infrastructure fall into such a state of disrepair that it is now coming back to haunt us?"

City officials told the newspaper the value of the water is difficult to measure. They also said extra work crews were hired from June until early this month to plug more than 11,000 pipeline breaks.

But records show many of those leaks took more than three weeks to fix and that the 9 billion gallons lost in September and October amounted to about 25 percent of all the water the city was producing.

Houston has 7,000 miles of water lines. City public works department spokesman Roberto Medina said the lines are replaced or upgraded after 20 years but said some of the pipes first were installed in the 1960s.

City officials blame the unprecedented number of leaks on ground that's shifted because of the drought.

Over the fiscal year that ended in July, Houston earned $2.81 for every 1,000 gallons it sold. That translates into $50 million for the 18 billion gallons lost from June through October, the newspaper said.

Alvin Wright, also with the public works department, said the only value to be assigned to the lost water is the cost of producing and treating it, which averages about 25 cents per 1,000 gallons. That puts the lost water worth about $7.5 million, he said.

Officials said water rates aren't likely to go up to cover the losses and extra money spent on repairs. Record sales of water during the drought pumped nearly $20 million more than anticipated into the water department budget.

Sandra Wegmann, with the Center for Houston's Future, said population projections show within 50 years, the city's water demand will top supplies by 35 percent, meaning infrastructure and pipelines need to be improved.

"Clearly, conservation will be a huge priority for the future," she said. "It needs to be included in the plans. I had no idea that much water was leaking."