FERRIS (CBSDFW.COM) – Employee errors, corrupt computer software and a rate hike combined to create widespread problems with water bills in the city of Ferris. The city is still trying to untangle problems that could go back as far as July.

The problems can be traced back to a city employee who made a number of data entry errors, according to city manager Bill Jordan. Then in October, Jordan said utility billing software mistakenly recorded customers as using no water for the entire month. The city raised water and sewer rates at the same time, causing more problems with how bills were calculated.

Sean Bishop’s bill for his family of four, showed his water use climbed from 3,600 gallons in July, to more than 11,000 gallons by October.

His friend Joe McIntire, however, showed us how his bill dropped to $40 in July, only to go up to $250 the next month. He was also charged more money, in months where he used less water than Bishop.

“And they can’t explain that,” he said. “They don’t have an explanation for that.”

Jordan said the city has replaced the employee at fault. A new software system is in the process of being implemented by next spring. In preparation for that, Jordan said the city would manually read every water meter in order to start with accurate data.

In cases where mistakes are not obvious, he said the city is going through bills with customers, and in some cases writing off under or overbilling that can’t be explained.

The billing problems add to frustration residents have with water quality in the city. Ferris uses ground water from two city wells. Its higher mineral content leads to issues with taste, feel and buildup in plumbing. In January, the water exceeded the state’s maximum level for fluoride, leading to a recommendation for young children not to drink it due to a risk of dental problems.

Bishop, McIntire and others said they use bottled water for cooking and drinking. You’ll see bottled water at restaurants and at city hall.

Jordan said at the time, the city increased the amount of water it purchases from nearby Rockett. It also received a $275,000 grant this year to install a larger pipeline to that water system. Expected to be completed in 2018, it will allow the city to mix a larger amount of surface water with ground water, eliminating some of the taste and quality issues.