Christchurch City Council says it is attempting to fix the problem, but it does not track how widespread the issue is.
A misaligned meter is when the meter has been wrongly connected to a different property than the one using the water.
Information revealed under the Official Information Act shows staff only check water meter alignments on an as-needed basis and have no process for tallying how many surprise excess water bills have been invoiced.
In one example, a landlord received an excess water invoice stating the bill had previously been sent to a neighbour by mistake.
Their water meter was misaligned with another property, meaning they had not been charged for the rental’s excess water usage since the targeted rate was introduced in October 2022.
They had to pay $192 for the previous 12 months of excess use, which they were not aware of.
Going forward, city council head of three waters Gavin Hutchison said staff intend to start checking meter numbers on invoices and confirming they are for the correct address before being entered into the billing system.
“Our intention is to increase the quality of data being received into the council,” said Hutchison.
The landlord’s brother, who The Star spoke to anonymously, handles bills for the property and says the practice until now has been “egregious and disingenuous”.
“The water unit have deemed it acceptable to invoice ratepayers for up to 12 months water usage when the resident has had no way of tracking this and has not received any prior warning or invoicing,” the man said.
He said the exact cause of the excess water charge at the property has not been determined, but believes it is a combination of leaks and high use by tenants.
Excess water user charges apply to any household which uses, on average, more than 900L a day.
Households pay a fixed rate of $1.41 for every 1000L they use above the average daily limit.
Water meters are installed by the city council, but developers, plumbers and property owners are responsible for correctly connecting private water pipes to the meter.
The OIA revealed a single or several unpaid invoices will not necessarily trigger a meter check by city council staff.
Staff generally only check meters if requested by a customer, or in some cases for large invoices above $400.
The city council will charge for excess water bills on misaligned properties for up to a year.
There have been about 1400 meter alignment checks since October 2022, but it is unclear how many of these were unaligned or led to unexpected excess water charges.