The customers affected live in the unincorporated Jones Dairy Farm and Willow Deer subdivisions just outside of Wake Forest.
Ed Buchan, Senior Analyst with Raleigh Utilities, said in 2005 when Raleigh and Wake Forest agreed to a merger, hundreds of homes inside the unincorporated subdivisions were incorrectly coded as being inside city limits; those homes were subsequently billed half the rate they should have been billed.
A system-wide audit in late 2017 caught the error and by March, all of those homes will be billed at the correct, higher rate.
"It's an unfortunate mistake and we can obviously sympathize with anybody in that situation because that is going to be a significant increase in your utility bill," said Buchan.
However, 74 homeowners out of the 589 in the affected subdivisions, were billed at the correct, higher rate from the beginning.
Sharon Hill has lived in Jones Dairy Farm for six years and said while her water bill is typically $120, her next-door neighbor was paying about $60.
Buchan said the city has apologized to those affected and while the city could legally retroactively charge customers for the rate difference for up to three years, it won't.
"You can't back bill somebody for a mistake that you made," said Hill. "But I think if nobody else has to pay that double rate, then I should be getting some kind of refund or credit or something for having to go through all this and knowing that I paid more than double what my neighbor did."
Why higher rates for those who are outside city limits?
Out of the 195,000 customers in the City of Raleigh Public Utilities' service area, 5,460 are outside city limits. They all pay double what someone inside city limits pays.
Buchan said it has to do with who the system was meant to serve.
"The water and sewer system is there in the first place to grow the tax base of a given community, not the areas outside of that community, the property tax values inside of that community," he said. "When you have to extend your water and sewer lines outside of that, there's just not as much value added for that community."