He contacted the council in January but was dissatisfied with their response, believing that a "wider investigation" was called for.
He also identified errors in the rates of several properties in Carrington Drive, where he said some homeowners had been undercharged by hundreds of dollars for several years. This had occurred because they were being charged half the sewerage rate and not being charged for rubbish collection, he said.
In April he met with council chief executive Jane Davis but became concerned when he was told the public rating database would not be updated to reflect the correct rates until July 1.
"I became suspicious they were not going to be rated at the full extent.
"If there is a shortfall, it is the job of council to check it."
Mr Kinnell said he was worried that the rating database "should be kept and maintained, and clearly it isn't".
Speaking after the meeting, he said he believed there were systemic problems with the council's rate calculations.
"Some of these errors have continued for five years without the council noticing. The errors are the result of incorrect data entry.
"To be fair, this is unavoidable. However, the council appears to have no system of checking the accuracy of the data entered -- I would call that a systemic problem."
Council corporate services manager Marty Sebire said seven properties in Carrington Drive and four in Mill Grove were affected.
In Mill Grove the error had resulted in a loss of $5779 in rates and $4059 in Carrington Drive, most of which could not be recouped as the council was unable to collect money owed from previous years, Mr Sebire said.
"The Local Government Ratings Act prohibits us from claiming back from ratepayers' amounts outstanding that arise from a correction to a rating error for years other than the current year."
Council had already been aware of the problem and had been correcting some of the errors before Mr Kinnell raised the issue, Mr Sebire said.
The council maintained a large database and some mistakes were inevitable, he said.
It was not indicative of a "systemic" problem, he said.
"These particular properties on Carrington Drive were, or are, zoned rural but have urban-type rates, so they are a little unusual. We've checked all of Carrington Drive and Mill Grove and they are all there [in the database]."
The miscalculation was a human error caused by the fact the streets in question were zoned rural but had access to urban services, he said.
Council had now implemented further checks and tightened up its processes to prevent any further errors.
"I'm confident that it's all in hand and it's not widespread at all -- but we are tightening up our system and adding some controls."
The council's hard copy database had been updated to reflect the correct rates for all the properties but this would not appear online until July 1, when the public version was updated.
The exact amounts owed by each property and the years it related to were confidential and could not be disclosed, he said.
